JANUARY 1997ISSUE #436

USA $3 .95CANADA $4 .95

International Edition

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Including Ham Radio Fun!r----l

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Soup up your RxWith a preamp

73 Reviews:WEFAX Demodulator

More CW funWith this keyer

AutomaticVoltageController

Build a ScopeMixerThe industrial-strength signal cleaner

•~RC

160-10 Meters PLUS 6 Meter Transceiver

1 All -Mode Operation (SSB,GW,AM,AFSK,FM) on all HF amateurbands and 6 meters. JST· 14S, same as JST·245 but without 6meters and built- in antenna tuner.

* JST·145 COMING SOON *2 MOSFET POWER AMPLIFIER . Final PA util izes AF MOSFETs

to achieve low distortion and high durability. Rated output is 10to 150 watts on all bands including 6 meters .

3 AUTOM ATIC ANTENNA TUNE R . Auto tuner included asstandard equipment. Tuner ser uncs are automatiCally storedin memory for fast asy.

4 MULTIPLE ANTENNA SELECTION ' Three antenna connec­tions are user selectabl e from Iront panel. Antenna se lection canbe stored in memory.

5 GENERAL COVERAGE RECEIVER · 100 kHz-30 MHz, plus 48­54 MHz receiver. Electronica lly tuned front-end filtering, quad­FET mixer and quadruple conversion system (triple conversionfor FM) results in excellent dynamic range (> l00dB) and 3rd orderICP of +2OdBm.

6 IF BANDWIDTH FLEX IBILITY · Standard 2.4 kHz filter can benarrowed continuously to 800 Hz with variable Bandwidth Control(BWe) . Narrow SSB and CW filters tor 2nd and 3rd IF optional.

7 aRM SUPPRESSION · Other interfe rence rejection featuresinclude Passband Shift (PBS), dual noise blanker, 3-step RF atten ­uation, IF notch filter, selectable AGe and all-mode squelch.

8 NOTCH TRACKING · Once tuned , the IF notch filter will track theoffending hete rodyne (± 10Khz) if the VFO frequency is changed.

9 DDS PHASE LOCK LOOP SYSTEM · A single-crystal DirectDigital Synthesis system is utilized for very low phase noise.

10 CW FEATURES · Full break-in operation, variable CW pitch. builtin electronic keyer up to 60 wpm.

11 DUAL VFOs • Two separate VFOs for spl it-frequency operation.Memory registers store most recent VFO frequency, mode, band­width and other imponant parameters for each band.

12 200 MEMORIES · Memory capacity of 200 channels. eactt ofwhich store frequency. mode. AGC and bandwidth .

13 COMPUT ER INTERFAC E · Built-in RS-232C interf ace foradvanced computer applications .

14 ERGONOMIC LAYOur · Front panel features easy to read colorLCD display and thoughltul placement of controls for ease 01oper­ation.

15 HEAVY- DUTY POWER SUPPLY · Built-in switching powersupply with "silent" cooling system designed fo r continuoustransmission at maxlmim output.

''''ReI aapanRtMito Co.,.iJd.430 Park Ave., 2nd Floor New York , NY 10022 Phone: (212) 355-1180 Fax: (2 12) 319-5227

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Corner Beam ModelsBand Max Dim WindLd Price

2 meters 4 ft <2 sqft $145220 MHz 4 ft <1 sqft $ 14570cm 3 ft cl sqft $ 115Dual 146/435 4 ft <3 sqft $ 165

ComerBeam can st ill be your beamwhen you join MARS at 143/148 MHz orlearn up with the sheriffs commun ica­tions interface team at 158 MHz.

Scanning Too?ComerBeam's gain & bandwidth ex­

tend monitoring ra nge from aircraft to tomarine & public service frequencies.•

10dS

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Measured CornerBeam PatternBeam Heading (degrees)

90 0 +90 +18°0 dB

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Your antenna makes all the difference at VHF and UHF-It de­termines transmitting ran ge. It sets the limit for weak signal recep­tion. And it decides what interference you' ll hear and create.

An omnidirectional antenna radiates uniformly in all direction,and it also hears noise and interference from every direction .

A directional ante nna not only sends your signal where youwant, it hears the signal it's pointed at, rejecting others . It also letsyou operate with minimal power, cutting interference you inflict onother stations.

CornerBeam's clean sharp patternwithout sidelobes or spikes reaches pastthe noise and interference to get the mes­sage through. Its wide rear rejection letsyou null out strong nearby signals to re­duce interference .

Look what CornerBeam does:-10 dB gain vs. dipole-40 dB Front-to-Back-60 degree Half-power Beamwidth-SWR < 1.1 : I across the band-No dimension over 4 ft-Mounts directly to mast or tower-Vcrtical or horizontal polarization-No need for offset or side mount

-180

CornerB

Cor ner Beats VagiA yag i with the same gain would

have a 10-ft boom. Yagi bandwidthwould be less than half. More important,CornerBeam produces no side lobes, noback lobes.

Improved Data Com municationBecause ComerBeam's pattern has

no unwanted side spikes, phase noise isreduced to a minimum. The result is re­d uced data error rate, faster packet cir­cuits. When you want a distortion freesignal, think CornerBeam, nOI yagi.

Co rner Beam for RepeatersIf your repe ater shares

a freq uency with another,the deep wide null towardthe rear could keep yoursignal out of theneighboring repeater'srece iver and tum a deaf ear Constr uction : Aircraft aluminum.to Its signal. A pair of Booms are square. Eleme nts arc 501-CornerBeams can be com- id rod. Stainless hardware includedbined to privide special ra- for tower and mast mounting acceptsdiation footprints . A Cor- up to I S ' dia. mast and may be ro-nerBeam aimed at an area tated for vertical or horizontal polari-your repeater hears poorly zation. Connector is SO.239 forcould improve service VHF, N female for UHF. Dual-Bandwhere incoming signals antenna has separate dri ven ele-from HTs are presently too ments, weighs only 10 pounds.weak. ComerBeam makes Dimensions given in table are forit possible to increase re- reflector ele ments & booms . Ipeater density while reduc- Options: Commercial Frequency $45 . Iing interference. Duplexer: Add $80 for VHF/UHF

Bandwid th Pays OfT Duplexer and cabling for single coaxWith its exceptional bandwidth, your feed of Dualband 146/435 Co rner.

ComerBeam can be put to work right out Shipping: UPS ground to continentalof the box without special tweaking. It USA ($ 11 S&H). Air Parcel Post tocan serve you now when you're working HI, A K, & Posessions ($ 14 P&H ).repeaters with an FM handheld, and later Canada ($ 16 P&H).when you set out to work satellites or go Allow 2 weeks for delivery.after small signal DX at 144. 2 MHz.r------------------,DYes, I want Performance in My Corner!I _ Send my CornerBeam: _ 2m, _ 220MHz, _ 70 em, _ Dual 146/435. I

I_ Oplions: _ DualBand Duplexer, _ CommerciaUMarine . Freque ncy: IName Arnt. Enclosed _

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without buying multi­band hf rcvr. Hear GeoAlerts for conditions at­fecting radio propaqa­ucn Very senM ive andselective crysta l controlled superhet, dedicated to listen­ing to V'N'N on 10.000 MHz. Performance rivals the mostexpensive receivers• RWWV Rcvr krt , PCB only .... ." ........" ...... , $59• RWWV Rcvr krt With cabt. spkr. & 12Vdc adapter $89• RWWV Rcv r weedztestec in cabt with spkr &

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Excellent 0.1S"V sen­s itivity provides goodreception even at dis­tances of 70 miles ormore with suitable an­tenna. No compa risonwith ordinary consume rradios or scanners ! Automatic mode provides stormwatCh, alerting you by unmuting receiver and providing anoutput to trip remote equipment when an alert tone isbroadcast.

Essential for airports, police and fire departments,CAP, broadcast stations, state and local emergency man­agers, amateur repeaters - anyone needing a professionalquality receiver. Because 01 its reasonable price, It Is alsohandy for bikers, hikers, boaters , hunters, farmers - anyone who needs up-to-d ate weather info and emergencywarnings, even from distant stations

Small enough for emergency or portab le use, rt can bepowered from a small 9-12V battery when needed , Crys­tal controlled for accuracy; all 1 Channels pr'Qvided(1 62.40 to 162,55).

You can buy just the receiver pcb module in kit form orbuy the kit with an attractive metal cabinet. AC powersupply. and buill- in speaker. It is also available factorywired and tested ,oRWX Rcvr kit, PCB only $19oRWX Rcvr kit wrth cabt, spkr, & 12Vdc adapter .... " .. $99oRWX Rcv r wired/tested in cabt wrth spkr & adptr $139

Access all your favorite closed repeat­ers with TO-S CTCSS Encoder/Decoder

Our new RWX is a vezsensitive andselective Hamtronics grade rece iver to

monitor critical w eather and emergency broad­cas t s from NOAAINWS or Environment Canada.

SUBAUDIBLE TONEENCODER/DECODER

Encodes all standard sub­audible tones WIth crystal ac­curacy and convenient OIPswitch selection, Compre­hens ive manual also showshow you can set up a frontpanel switch to select be­tween tones for several re­peaters. Receiver decodercan be used to mute receive audio and is optimized forinstallation in repeaters to provide closed access. Highpass filter gets nd of annoying buzz in receiver.oTO-5 CTCSS EncoderlDecodar Kit " " only $39oTO-5 CTCSS Encoder!Decoder Wiredflested . , __ ..$59

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Join tlle fun . Get strikingImages d inK:t1y from tlleweather satellites l Avery sensitive wideband fmreceiver optimized for

reception of NOAA APT and Russ ian RussianMeteor weather fax images on the 137 MHz band,Covers all nve satell ite channels. Scanner circuit andrecorder control allow you to automatically search forand tape signals as satellites pass overhead, even whileaway from homeoRI 39 Recel.er Killen ce, e ~._...~.._...~..~,..~.._.._.._ _._ .._$159• RI 39 Receive' Kil with eeseend I2Vdc pwr edepter _ ..~,_ $189.111 39 1leceive, Wired in caUlwith I2Vdc adapter_ ._._._ ._ n39• Internal PC Demodulalnr Bnard and ImagingSoftwara _$199• TulnolilaAntenna ~.._ ._...~ _ ..~.._ ,_ ........~ _ ..~.._,_ $119• Weather Satellile Handbook ~...~.._ ._..~..~ ~.._ ..~..~..~... no

A microprocvssor-c:onlrolled repeater with full auto­patch and many versatile dlmf control features atlen than you might pay for a bare-bones repeater orcontroller alonel

Kit still only $ 109'w&-t $till only $129550,"" ,n, '''."','13. •"~,, M",lIo" m M", "u"""'v"o',fDigita l Voice Recorder Option only $100.Great for voice 10 or making club announcements.REP-200C Economy Repeater. Voice ID, no dtml orautcpatch ... " ........, Kit only $195 , w&t $1195•REP-200N R"pvat"r. No controH~" so you can use yourown. .. "" ........ " . Kit only $695, w&t $995.

LNG-( ) GAAs FET PREAMPSSTill ONLY $59!o Make you r friends sick withenvy ! Work stations they don'teven know are there,• Instali one at the antenna andovercome coax losse s.o Available for 28-30, 46-56, 137-152, 152-172, 210-230,400·470. and 80D-960 MHz bands.

~LNW-( ) ECONOMY PREAMPS

" . • ONLY $29 kit, $44 wired/tested. . 0 M,niature MOS FET Preamp

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• Available for 25-35,35-55, 55-90, 90-120, 120-150.150-200,200·270, and 400-500 MHz bands.

No need to spendthousands on newtransceivers fo reach band!o Convert vhf and uhf signals tal/rom 10M,• Even if you don't have a 10M rig, you can pick up verygood used xmtrs & rcws for next 10 nothing,• Receiving converters (shown above ) available forvarious segments of 6M, 2M, 220, and 432 MHz,o Kits from $49, wiredflested units only $99

o Xmitting converters (atleft) lo r 2M. 432 MHz,o Kits only $89 vhf or$99 uhf,o Power amplifiers up to50W output.

Go on a ham satellite adventure! Add an­

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You'll KICK Yourself TRANSMITTING ANDIf You Build a Repeater RECEIVING CONVERTERS

Without Checking Out Our Catalog Fir st!

VHF & UHF AMPLIFIERS.Output levels from 10Wto 100W Starting at $99.

FM EXCITERS : 2W output. continuous duty.

TA51 : 8M, 2M. 220MHz, ~

...kl1$99, wit s169, ~~~~:._ •TA451 : 420-475 MHz, ffidJe;f)5.-'

. kit $99, wit $169. - "TA901 : 902-928 MHz,(O.5W out} ....... ,wit $169.

FM RECEIVERS :• R100 VHF FM RECEIVERSVery sensitive - 0,15uV, superbselectivity - both crystal andceramic IF @ers for :> 100 deat :l:1 2kHz (best available any­Where), flutter-proof squelch ,

For 46·54 , 72-76, 140-175, or 216-225 MHz,......... ", ....... , " ........ " . kit $129, wl1$189.

o R144JR220 RCVRS. like Rl 00. with 2M or 220 MHzhelical resonator in front end " ..,kit $159, wl1 $219.• R451 FM RCVR, for 420-475 MHz. Similar to above,

." .......... .. kit $129, wl1 $189.• R901 FM RCVR, 902-928MHz ...$159, wit $219.

Hamtronics has the world's mostcomplete line of repeater controllers, cwand voice id boards, dtmf controllers,autopatches, ctcss boards, exciter, pa,and receiver modules. Here's a sample...CWIO. Traditional diode matrix, permits field changes;use with CO R-3 ,..... _.... , ", ..... kit only $S9

J!l{g''t1'~ - - CWID_2. Miniature cwid board,

1," eprom-corurolted. easy to build., " .. ", .,_ .... , . o n ly $54fkit, $79 wit.

DVR-1. Add real speech to your repeater, Records yourown vcce up to 20 seconds. Use for vece id or to playclub announcements. ,....... .." $s9Jkit, $99 wit

COR-3. Inexpensive, flexible COR module w;lh timers,courtesy beep. audio mixer .... " ...... .", .... kit only $49

COR-4. Cornp jete COR and CWl O all on one board.Low power CMOS logic. timers. courtesy beep. 2nd rcvrinput. id in eprom " " '" only $99Ik it, $149 wit

COR·5. Microprocessor controller with all the bells &Whistles! Full autopatch, reverse ap, phone remotecontrol, lots of dtmt control functions, all on one board,as used in REP-200 Repeater........." " ....... " ......$379 wit

COR-6. COR timers , courtesy beep,, -~_

voice KJ, Like COR & OVR-1 on one ".~,'!'j-~,..,j.8board! Record your own voice up to ",.\'20 seconds. l ow power CMOS, non- ;r:, • Ivolatile memory. ~ ~ ,.,,, kit only $99,wlt only $149. ~ ;

AP-3. Repeater autcpatch. reverse autopatch, phoneline remote control , Use with TD-2. ...", ........ " .....kit $89

TD_2. Four-dlgl it OTMF decoder/controller. Five latchingon-off functions, toll cali resmctor. .. .. " ...... ,kit $79

TO-4. OTMF controller as aboveexcept one on-off function and notoll call resuctcr. Can also use forse~ctlve calling: mute speaker unlilsomeone pages you kil $49.

TO-3. CTCSS Decoder/Encoder Prevents repeateraccess unless lone is present. Can also be used withmobile to access repeaters. ..,..... kit only $29.

JANUARY 1997ISSUE #436

DEPARTMENTS34 1996 Annual Index

WB6IGP " Above & Beyond

73 Ad Index

KB1UM 46 Ask Kaboom.. Barter 'n' BuyK41PV 50 Carr's CornerNZ9E 54 Ham to HamWB2MGP 47 Hams With ClassWA5ZIB 52 HarnsatsKCOV 57 Homing In6 LettersW2NSOI1 4 Never Say Die

84 New ProductsW1XU 87 PropagationWB8VGE 63 aRP, aRX

47,56, Radio Book Shop

6'"WA3AJR 46 RTIYLoop88 Special Events85 Updates

Including Ham Radio Fun!

AmateurRadio Today

TABLE OF CONTENTS

®

An Enhaoced Automatic Voltage Controller - N4UAUMilXe /his project even more useful.

The ScopeMixer - N6GKCAn adventure in ham radio systems integration.

Rechargeable aanertes - NZ9EThe bottom line.

A Flexible Keyer - W2GOW7A weekend01 investments: a lifeUme of ease.

Simple Mods lor the Ramsey FXTransceiver Kit - NOBLXCuslomi7e it!

FEATURES

Build This Receiver Preamplifier - W9CHV.., And usejustaboutanytf1Jng for an antenna,

A Positive and Negative Power Supply - KB4ZGCA simple OfIe-€vening prqeet.

26

31

17

10

24

42

"

THETEAM

Advertis ing satesFrances HyvarinenRoger Smith603-924-0058800-274-7373Fax: 603-924-8613

Associate PublisherF. I. Marion

FounderWayne Green W2NSD/ l

Nitty Gritty Stuff

Prisc illa GauvinJoyce SawtelleDavid Underwood

Contributing Culpr itsBill Brown WB8 ELKMike Bryce WB8VGEJoseph E. Carr K41PV

Michael Geier KB1UMJim Gray Wl xunChuck Houghton WB6IGPDr. Marc Leavey WA3AJRAndy MacA llister WA5ZlB

Dave Miller NZ9EJoe MoeHK00V

Carole Perry WB2MGP

CirculationLinda CoughlanHelen Senechal

Associate Technical EditorLarry Antonuk WB9RRT

Data Entry & Other StuffChristine AubertNorman Marion

REVIEWS HAM RADIO FUN SECTIONBusiness OfficeEditorial - Advertising - Qra..iabonFeedback - Product Reviews73 Amateur RadiOToday Magazine70 Route 202NPeterborough NH 03458-1107603·924·0058Fax: 603·924-8613

35

40

HFx lrom Pacific Sierra Research CorporatiOn - N1 VXWNew prqJagation forecasting soflware.

MuItlFAX®AMlFM WEFAX Demodulator - WB9RRTFine-luninga satellile lracking system.

K20AW 64 Communications Simplified,Part 13

NaPTG 69 Build a Well-Regulated PowerSupply

N3JSU 74 A Hamlest Computer ShoppingGuide

K2FZ 78 A Retiree's HF Mobile OperatiOfl

Reprints: $3 per articleBack issues: $5 each

Printed In the USA byQuad Graphics

Manuscripts: Cont ributions forpossible publication are mostwelcome. we'll do the best we can toreturn anything you request, but weassume no responsibl lity lor lossor damage. Payment for submittedarticles will be made !..porI pl.tllication.Please submit both a disk and a hardcopy 01 your article (IBM (ok) or Mac(preferred) formats). carefullychecked drawings anc:I schematics,anc:I the dearest best focused andlighted photos you can manage. "Howto write for 73"guidelinesareavailableon reaest. US d nzens must Irl'::h..ostheir Social Security number withSlbmitted manuscripls so we canSlbmrt rt to u know who.

On the cover: Winning entries from 73's "QSL of the Month" contest, June 1996 throughJanuary 1997. Winners for each month have received a free one-year subscription or extension.

Feedback: Any circuit works better with feedback, so please take th e t ime to report onhow much you like, hate , or don 't care one way or the other abou t the art icles andco lumns in th is issue . G = great !, 0 = okay, and U = ugh. Th e G's and O's will becontinued . Enough U's and it 's Si lent Keysvil le. He y, th is is your commu nicat ionsmediu m, so don't ju st sit there scratching your ... er. ..head. FYI: Feedback "number" isusu ally the page num ber on which the artic le or colum n starts.

73 Amateur Radio Today ( ISSN 1052-2522) is pu bli shed month ly by 73 MagaZine. 70 N202, Pete rborough NH03458- 1107. The en tire contents 0 1996 by 73 Magazine. No part of this publica tion may be reproduced withoutwritten permission of the publisher, which is not eu that diff icult to get. The subscripti on rate is : one year$24.97. two years $44 .97; Canada: one yea r $34.21 , two years $57 .75, including postage and 7% GST. Foreignpostag e : $19 su rfac e, $42 ai rmail add iti onal per yea r, pay able in US funds on a US bank. Secon d cl asspostage is paid at Pete rbo rough , NH , and at addit ional ma il ing off ices. Canadian second class mail reqrsnauo n#178101. Canadian GST repts tranon # 1253933 14. Mic rofilm ed ition: University Microf ilm, Ann Arbor MI 48 106.POSTMASTER : Send ad dress changes to 73 Amafeu r RadiO Today, 70 N202. Peterboro ugh NH 03458-1107.73 Amateur Rad io Today is owned by Shabroma t Way ltd. of Han cock NH.

Contract : Have you tried microwaves ? How about amateur te lev ision? When's the last l ime you home-brewed apiece of eq uipment? Rea ding this contract comm its you to t ryin g something new or long -neglected , The 73adve rt isers can supply you with wha tever you need ... j ust don't fo rge t to tel! 'em 73 sent you.

Resolutions

Hum"'" I on your FHdtHtclc urd

Wayne Green W2NSOIl

the FCC 10 hacl.. away at us. Yes,of course our AR RL ham lobbyin Wash ington shou ld have pre ­vented this. But r m not sure wehav e even a vestibule there ,much less a lobby.

Congress. a collcc tion of poli­ncians (mostly lawyers) youkeep re-electi ng. can smellmoney through 10 feet o f lead.And thei r main pu rpose in get­ting elected seems to he to spendas much of yo ur money as theycan, incl uding borrowing asmu ch as possible fro m the fu­ture. So the aroma fro m the re­cent FCC spect rum auctionmade Congress impaticnt withthe FCCs sfo .....ness in generat­ing more money for their porkfutures,

Just before going home forthe holidays, Congress wb jppcdthroug h Public Law IQ.I-W8,and it was signed hy Clinton0 l'1. -tth. This lill ie baby sliceso ff two 5 MH z chun ks of ourn em band 10 be put up forauction. Sl icc and dire.

I know you wo n't forgi ve mefor going back 111 tim e 30 years.That' s when the ARRL stoppedour ham gro wth dead and almosttotally destroyed our Americanham indu stry. wiping out about9O'l o f o ur ham dealers as well.But if thi s ca tas trophe had nothappened-if amateur radio hadbeen permitted to continuegrowing as it had stead ily in theprevious I7 years-today we ' dhaw over 5 mil lio n ha ms , an dour coun try would have over 4mill ion more technicians, engi­neers and scientists than it doesnow. And I don' t think we'dhave eith er unused microwaveham bands or any problem withCongress and the FCC slowlyputting what's left o f us out ofour miseries.

I don't think we would havelo s t all of o ur co nsu me re lectro nics industries to Japaneither.

w here have the kids all gone ?They ' re rushing 10 the Internet,where yo u' ll rind endless tee n­agcrs having a ball with chatrooms instead or chasing DX orgahbing o n 75m, Or gett ing onour ham satel lites with packet,

If an ARRL d irector were toco me to you , wringing hishands. asking what. oh what.can he done about thi s , whatwould you say?

I' ll give you a hint , Th ere aretwo things I can think of Ihat theLeague cou ld do to st.m turningthi s s itua l io n arou nd . No ,

C'..ollfilllll'd on pag e 7

The C a mel's ~O~

As if we don' t have eno ug.hlrouble wilh the FCC slicing o ffchunk s of our unused hamhands, now Congress is forci ng

Should I keep re peating mysel f !A good part of happiness is inyour family, So how much allen­lion are you paying 10 romance?Wh ile a ne .... rig ma y reall y getyo"r juices going, your wife willbe far more responsive to ro­mance, And don 't you forget it.

One o f thc eu.. iest ways 10 re­kindle romance is with dancing .Yes, I 1.. 11 0 W , yo u're a klutz andwould rather turn off yo ur linearand run hnrctoot than go dane­lng. So get one of Sherry 's how­to-dance videos and see whathappens. You could use the ro­mance and Sherry can use theexira bustness. Call Soo-·t)­DA:\CE for a catalog.

what will it take to gel you tomake the hi g health change for' 97? With daily exercise. ahealthy die t, stoppi ng poisoni ngyour body, drink ing enough wa­ter, and stuff like that? 1"0chance, ch? Well , 1997 is go ingto be whatever you make it, andthe new year is a fine time tomake the big changes in yourli fe that wi ll sec you livingheal thier. happier. and wealthier.Or not . You can ma ke my yearfor me by letting me kno..... thatI' ve helped you decide 10 makechanges. Will I be gell ing a notefrom you, or perhaps a hand­shake and some encouragementat a hamfest?

I haven't be en invited to the' 97 Hamvcnuon yet, hut per­haps 1" 11 sec you there in ' 98? Anew, trim, slim, grinning you?

I got a lette r recentl y fro m areader who thanked me for push­ing him many years ago to starthis own electronics-orientedbu s ine ss. His company is nowone of the top in the fie ld andhe's having the lime o f his li fe .

pou ring through. Well, il d idn'ttake long for me to convert anSCR-5:!2 t ransmitter to em andbuild a converter for my SX- 28.As far as I kno w, I .....as tne firststat ion o n 6m in New York Cityand I had a ball.

In those day s everyone wascrystal -controlled, so with mysurp lus freque ncy meter I couldte ll who was who locally j ust hychecking the frequency. Therewas a scattering of hams aroundNo rthern New Jersey. Long Is­land. up state New York, lindConnecticut.

To help other hams find out.....hen the hand was ope n I set myr ig: up on 50. 1 ~IHL w irh a codew heel l..eying it as a beacon.That attrac ted Perry Ferrel l. ..... nohad a contract ..... ith the Air Forceto invest igate the propagat ioncharacteristics of the band. I gota nice Rad io Amatcur Scientifi cObservations (RASO) certificatefro m the Air Force for my par­ticipation.

Later, when Perry became theedi tor of CQ, this helped me gethim interested in my RITYwork. And that led to my doing: aRITY column in CQ, wh ich ledto my' gelling Perry the job aseduor o f Popular Electronics;And that led 10 my becoming theedi tor of CQ, And 1" f1lled to mystart ing: 7.r

BUI then, every new thing I'vedone in amateur radio has led tosome son of adventure for me,so I hope you wo n' t gel fed upwith mc proddi ng you to try newmodes and bands . I get so dis­cou ragcd when I lis ten to 75mnets and 20m rou nd tables.where it is obvious that everyoneis just marking time with theirlives unt il the Silent Key guycomes calling. How is that bette rIhan watching ball games orsitting in bars? It 's Iil..e going toa gounnel feast and eat ing ahamburger,

l'\'e wriuen about health,wealth, and happine~ ~ hefore.

4 73 Amateur Radio Today · October 1996

NEUER SRV DIE

The beginn ing o f the new yearis a good time to make changes.Thc Christmas holidays win d upthe old year, giving us a chanceto make a fresh start with thenew o ne. What changes are yougoing \0 make?

Yes, of course I have somerecommendations. lI l." y, if yo ugive me an inc h, 1" 11 try to re­vamp yo ur whole life for yo u,For the f-ette r. Arc yo u game 10

try some changes that wi ll (a)\ lake you much healthie r? (h)Happier? (c) Wealthier? (d) Do abette r job with your kids? (e)Bring adventure into your life?(0 Accomplish some thing you' llbe proud to be remembered for?

That 's a tal l order. but doable.unless your (bad) habit patternsare so thoroughly ingrained thatyo u arc no longer even capableof change.

Le t 's start with adventure ,since that's closest 10 ho me,hamwisc. Pick somethi ng yo uhav en' t done yet, hut whic hso unds like fun . and get crac k­mg. It could be slow-scan.RITY, packet , em. 10 Gill. theham satell ites, or even 160m.Read, a..l.. questions, sian settingup the gear, and learn. I hopeyouIl kecp careful notes so youcan help others avoid the pitfa llsand blind alleys. \laybe I caneven get you to do some artic lesfor 7P If I can ju st gel youstarted. I guarantee you' ll he infor adventu re.

Take.' 6 meters lor instance.When the hand was ope ned afterWW II. I didn' t think much aboutn. I was busy having fun up on10m and zm. Then one day Iturned on my oid pre-warMeissner FM tuner, The F\ tbroadcast band, as I recall, used10 he al 50-56 \ IHz, with the 5mham hand from 56-60 \ 1Hz.Suddenly I wa~ hcaring a wholehunt'h of 5-9 Wbs and W7s

DlJcevER

Now you can be in the same league as James Bond. Thistransmittef JS so smal!hat it can fil i"1[0 a pack of cqerenes .even irlClWlng a CCO TV camera and battery! Model airplaneeomcsase put the MTV·7A into eepenes fora dynamiteView

from thecockpit. and the MTV-7A is the lIansmitter 01 choice forbaI!oon taccres. Transminer featUfes synthesized,crystal con­lJolled operation fa drift-free transrrissijor1 01 botr. audio andvideo 00 your croce of frequencies: Slandard UHFTV Chanr1eI52 (wheh shaukl oriybe used outside III the USA 10 al'Oid 1'iO­lating FCC rules), and 439,25 MHz or 911.25 MHz wtlidl are inthe amaleur ham bands. The 439 25 MHz unit has 1he rillyadvantage 01 being able 10 be recei'led on a r9Qular caee­read~ ' TV set tuned to Cable channel &8, or use our ATV-74converterand leceive it on ril9lJlar TV channel 3. The 911.25MHz UIlit rs suited fOf ~icallOl1S v.toere recep~on on a reQlJIarTV is 1101 desiled, an AlV-79 Il'IJSt be used for operatiOn. 'theMTV·7A's oulpuI power is almost 100 mW, SO lraosmittino rangeis prettv much ·1ine-1ll·$j!1Jl· whiCh can mean many milesf TheMTV·711 accepts standard lliack and white or color video andhas its own. on-ooard, sensi tive electret micorphooe. The MTV­7A is available in kit form or fully wired and lesled. Since thelalest inSMT (Surlace Mount Teemoiogy) is used to provide forthe smallest possible size. the kil version is recormleOded forexperienced builders only. Runs on 12 VDe@ 150 mA andincludes a regulated power SOUfCe for aceo camera.MT'H A, UHF TV Channel 52 Transm~ler K~ •.••.• •... $1 59.95MTV·7AWT, FUlyWired Cf\aMel52 Transmiller . •• ... . $249.95UTV·7A4, 439.25 MHz TV Transmiller Kit . •• ••• ••• . . . . $159.95tITV·7A4WT, FullyWired 439.25 MHzTlansmiller ." ., . $2 49.95tITV·7A9,911.25 11Hz TV Transmitler Kk . •. •. •••. • . .. $179.95tITV·7A9WT, FUllyWired 911.25MHzTlansmi1ter " •.•. $269.95ATV·74, 439.25 MHz Coovel1er Kil .. •. •••. ••••. •• , .. $159.95ATV·74WT, FUllyWired 439.25 MHz Converter.•...•... $249.95ATV·79, 911.25 MHz Converter Kil . ••••. ••••••. •" " $1 79.95ATV·79WT, FullyWired 91 1.25 MHz Converter ••, , .. , , •$269.95

S<.per small, hiQh quaityfully asserrbIecf B& WCCO TV camera the s eeoj an ice cube! Provi4es elCellent pictures inlow li;jht (2 Ju~) . oruse (l(I" fR-1 Infra-Red ~t source 10 i'lVis~ lluminale anentire room on a pilch black night! fmagine the possibilities",told it iolo a smoke detector. waU clod, larTlI, book. radio ,Exacl same camera thai's in big buck deteclive casccee andstores. Krt includes: fuly assembled CCO camera rrocfule. COIl­nectors, io1:erface PC board kil with proper vottage regLlatiOnand fihering. hook-up details. even a mini microphorloe for sere­tive sound!Two models evatee: Wide Angle Leos 3.6rm1112.adjuslable kcus lens, 92 iKlgl"ee view; Piotlole leos 5.5mrrll14.5,SO del)'ee view. The Pinhole l ens is physically men naner andprovicles even grealer depth oj locus. The camera itsell is 1.2"square , The Wide Ar!:l le lens isaboul1·1oog. Pinhole lensabout 112", menace PC:: board is 1· l 2" and uses RCA jacks foreasy hook-up to VCRs, TVs Of~e runs , Power required is9to 14VDC@15OrnA.ResoMioo:36Ol35O IIoes. Ins1rOOioomanual ecotens ideas or1 rrouoting and disgois~ the Mini­Peeper aloog with ioto00 adding one 01 our TV Transmitter kilS(sllCll as ne MTV-7unil below) for wireless transmission!UP·1, Wide AngleLens CCD TV Camera OutIh•• . . . .• •$169.95UP-1PH, Pin-Hole Lens CCO TV Camefa Outli1. ..... ••$189.95

ORDERING /Hf"O: Sal>SlacllOO GlJ a'anre«l Examtne lor 10oays, if notpleaseo:l. <etvm 01 original form for 'efund Add $4.9510' S/lippiOg.lIan·dlillg and insu'ance, O'dllfs urmr $20. add SJ OO N'f 'esiclents add 7"4sales ta>: Sorry, no COOs. Foreign Ofde~ add m lor surlaoo ma~ oruse credit~ and SPf!Q!y snipping method

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Dialed ptJooe numbers,repealef codes, controlcodes, anywhere toucl1­

10005 are used, your TG-1 wi l deeooe and store ao~ 0I.XrbeI ~

hears. Asi~ Ilook-up 10 an! racio speakeror phone line isaWthaI is requi"ed, and since the G-1 uses a central offiCe ~al itydecoder and microprocessor. ~ will deeooe digits at vil1ually anyspeedl A256 dig~ O(l(l·volatile memory stores oorrtlers for 100years - even with the power turned 011, and an 8digrt LEDcIlsplayallows you 10 scroll through anywhere in memory. To make il easy10 pick oul nurrbers and codes. a dash is inserted belWeen anygroup or sel of n\llTters that were decoded more than 2secondsapart. The TG-l runs from any 7 to 15volt DC power SOUfce andisboth voltage regulated and crystal cootrol led for the ultimate 10

stability, For sland-alorle use add QlI" matching case sel for aclean, professlOOaJty finished project We have a TG- l comectedup here at lhe Ramsey factory 00 the FM radiO. Irs ful to see lIlephone numbers that are dialed 00 the rnomiIllj radiO shoW!Although the TG-1 requiles less than an everung 10 assel'l'lb1e(aoo is ful to buikl, too!).we otIef the TG-1 fully wired all:! testedinmat~ case for a special price,TG-1, Tone Gfabber Ki1. . •....•... . . .•.•. •.• .. •. .. ' 199.95CTG. Matching.Case Set lor TG-1Kit , . , , , , , , , , . , . •.. 14.95TG-1'wr,FuIly'Wired ToneGrabber wilh Case . •.• •••. •$149.95ACI2-5, 12VoNDC wall Plug Adapler •••••••• •• ••• ••• •$9.95

oecooe alilhat gibberish! This is thepopular descral'l'lb1er I scrambler that youve read aboul in all theSCanner and Electronic magazines. The technology used isknovm as speech inversion which is corJ1litible with mosl tord­less phones and many police department systems. hook rt up toscamer speaker teminals and you're inbusiness. Easily c0nfig­ured for any use: mike, IVle Iev~ and speaker out!M'inputs areprOl'iOed, Alsoconmuni:ate in total privacy over telephone orl adiO, lull duplel operation - scral'l'lb1e and unscramble aI thesame lime. Easy 10 tIli ld. all complel circuitry contained innewcustom ASfC chip for clear. clean audio. RlXlS or1 9 to 15VDC.RCAphono type jacks, CU matching case sci adds a super niceprofessional rook toyour kit.S5-70A, Speech DescrambierlScrambler Kit ••••••••••• $39.95css, Custom Ma1ching Case and Knob Set •••••••••••$14.95S5-70AWT, FUlly Wired S5-1M willi Case $79.95AC1 2·5, 12 Volt DC Wall Plug Adapler $9.95

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We alW offer a Il9hpower eXJXlfl version of the FM-l00 /hal'sfully aSS8lT1bled with one waftofRF power, lor I7llJes Iiprogramcoverage. The export version can only be shipped OUfSide rheUSA. or Wll/lin me US jf~Ilied bya sigl1(}(j statement Itlatrhe urll will be expotfed.FM-1OO, Professional Rl Stereo TransmitletKit . •. ••••sm.95FII-1OOWT, Fully Wiled High Power FM-100, . , . , •••••• $429.95

WOO1s smalIesl FM lransmner,Size 01 a sugarcubel UsesSMT lSuriace Mount Technology) devices and rrini electre1 COIl­densef llJcropllone. even ltle banel)' is incilldad. We g;"'e youtwoCOfT1llele sets III SMT parIS 10 allow fa any errors Ofmishaps·buikl ~ careluly ard you....e got e~lra SMT parIS 10tluikl another! AOOiO quality and pick.up is unOOlievable, trans­rrissijon range up to 300 leet. tunable to anyw!lel"e in standardFM band 88 tol06 MHz. 7iB"w ~ 3/6lll 314'1.FM-5Nicra FM Wireless Mike Klt. •••• , ." ., ., •. ••. •. $19.95

Super sta~ . drlfl free. /lOt affecled byl~alUre , metal orYQll" body' Frl:lQl.lenCy is sel bya Cl'ySlai in the 2meter Hambaoo III 146.535 MHz. easily pICked up on any scanner radio or2meter rig , Changing the crystal 10 put freQUellCy anywhere inthe 14010 ISO MHz range-oystals cost only live or Sil dcMlars.5ensilrle electret conderosor m.ke picks up whispers anywhereina loomand transrm up 10 114 mile. Powered by3 YOU Lithill11or pair 01 walch batlElfies wt1ich are inCluded. Uses the tatesl inSMT surface rno!.l'1l parts and we even incllJ(!e a lew el tras incase you sneeze and loose a part'FJI.6, Crystal Cootrolled FM Wireless Mike Kh •........ $3U5Fll-6WT Fully Wired FII-6 •••• •• •, . , ."" ., $69.95

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CtRCLE 34 ON READER SERVICE CARO

Numl1er 6 on your FHdback C/lrd

LETTERSFrom the Ham Shack

xen V. Fr iend W2AM\'. Thank greater diameter, the brush and leadyou for printing WA8YKN's anid l: will he isolated from the rotatingon "free energy' devices which magnetic field with a consequentappeared in the September issue. reduction or elimination of gcrer-

Having read several an k les on utcd power."zero-point" energy without the Going back to the smaller cop-term being dcfmcd, I found his CJ\- per disc, we can relocate the brushplanation enlightening. 10 a slip ring mounted on and insu-

Concerning the di"''l1ssion of thc larcd fmm the shan and well out of" :"0/" machine. ho wever, I submu the magnetic field. Restore the r-ir-that Ihc machine fo llows known cuu by soldering ajumper wife be-laws ofelectr ical power generation tween thc outer edge of the copperby mcdlOmic":l.I-magnctic meansand disc and the slip ring, Once again,draws no power from ":-'; space' or with thisbrush and its lead now iso-other SOl IR..'CS. Any vonege or cur- luted from the rotat ing magneticrent generated is strictly the result field. the power generated wilI beof relative motion between a CDn- zero.cuero- and a magnetic field as oc- Ihave verified the above withthecurs in any gener.IIDr or alternator help of a fractional borscpo.....er OC(read your ARRLH",ul/Jo"/,;,.). I also motor, four 1. 1r diameter ringsubmit that the rnagrctic fie ld docs magnets and some lathe work.roene csonc .....nh the magncric cyl- Measured output at 2,300 rpmmoer, in spill" of Tcsla's reponed whilc using a 1.2 ~ diameter brassconclusion that it remains sialion- disc was.. 2.75 mv open circuit andary (a point discu ssed hiler). 1.6 rnA sh ort-circuit current, With

Anyunc determined 10 construct a 1 .5 ~ diarnete r brass discor the slipa co py of Depalma's mach ine ri ng versjon there was nodctcctnblc

would be well advised to first build output.an inexpensive small-scale version. WAXY Kr-.; also notes that rotat-as I did. for tcsting after consider- ing the magnet alone produced noing the following discussion . voltage in a stationary disc and

In this discussion. it is assumed caused Testa to conclude that thethat the copper disc. shaft and mag- field dill not rotate with the mag-ncts shown in Flg.3 0f WAKYKN's net. This conclusion is unreason-article all rotate as a single linit and able if one considers a cylindrical

the disc is elect rically connected III magnet that has a non-uni Formthe shaft. Observe that in Fig. 3 of fi eld. It appears to absurd to imag-the article the magnet fl ux (not inc th at the non -uniform fi eldshown) surrounds the entire rylin- would remain non-uniform and .'0101-der, while becoming weaker with lionary while the source ofthis fielddistance from the cylinder. This is rotated,basic magncnc theory, WASYKN cites a Depalma test

Again referring In Hg. 3, n ote whichproduced 1.05 \'Olts aI7,200that the brush (and pan of its lead amps. hut it is not slated whetherclosest to the brush) in lxml:ll..1 with this was anopcn circuit voltage andthe l'oppcrdise is NlIlllxl in l!lc outer short-circuit (no load resistor) cur-magnelk nu x from Ihe cylindcr, rent. Such a high current would Ix1be t.rush and ils lead are station- cXf'\X"1cd in a soon circuil fed hyary while the magnclk field rotales the inlcr:l\.., ion wilh an inlense mag-so thal lhcre is relati\·e motitm he- netic field rolating al high rpm.tween them, which induces a \011- Both current and \'ollage can beage in the brush 3Ild lhat part of its expected to d rop dramalically iflead ..... ithin the flCld . 1bc induced mea.<;urcd wilh a suitable lood on\"Oltage will depend on the ..peed the oulput.ofrolatton and flu:\ densilyhut.due I h:n·e a copy of a data sheet onto the Iimilcde.\~ure 10 the field. another DePalma tcst which sllowsthe \'ollage will be low. n,i,f is tilt' 1.872 volts and 3A92 amperes,.w le .ffHIR't' oflmy pOll"er /?ent'rlltt'd which they multiplied together toby this machine 3... c\·idc..-nced by the gct an output of 6.538 walts. Fromoosenalions. If the copper disc is thedata sheet it is obvious Ihalthesereplaced t.y one of signifi l:antly arc open-circuit \"Ullagc and I;hOl1-

6 73 Amateur Radio Today · January 1997

ci rcuit current readings and thecomputedoutput is therefore mean­ingless (again, read your ARRI.Ha/l(/hook).

With this machine all may not he<1-0; it at first seems and your effortsmay be bette r expended on someother device.

Spoilsport.., \\(Iy ll("

Warren Rudolph W,*OIl~1.

Wayne. you wondered how manystill have the October 1960 37c is­sue. I haw ev ery issue from #\ tonow, all in binders. I was licensed\\'4011\1 aher WWII and haveheld the sarne call ever since, I ama c ha rtered member of th eShenandoah Valley Amateur RadioClub and obtained my first classcommercial license and radar en­u.lr;ement. I've also written an k les\\ hich haw been published in sev­eral radio milgil/incs. I went on theWinchester police force in 1942 asa dispatcher and ret ired as Chief ofPolice in 1980 with the rank ofmajor. I am presently active on 10and 2 meters and am an acti vemember of the local rad io club.

non waucrs WAfWC A, Reyour August editorial and keepingour 144, 220. and 420 ~1Hz hands:Perhaps we should pitch to the p0­

tcutial buyers Ihat we need at leasta couple of ~lHz for amateur radiobecause it provides a "hands-on"training ground for and a placewhere future technicians and engi­neers can develop an interest incommunications and elect ronics.something they do not get in tradeschools and colleges. And regard­ing the sale of the spectrum. I be­lieve that it should he leased for aperiod of time with the lessee pay­ing an initial fee which is the high­eSI hid and then a yearly teasepayment based on a perre r nage ofwhaltbe)" paid initially for Ihe tennof the lease. Th is pro\'ides a con·tinuing revenue stream to the gO\.'.cnUllent fora public reSUUfl'C beingused for commercial and pri\'alegain. Why? Because the spectrumis a nalional re""-lUfl'C that shouldbe kcpt publicly held while gener­atingan initial and acontinuing teV­

enue stream for thc pri\'ate usc- o fthis puNk re~n:e, f I J

Iha\'e hccn a ham since 1962 andha\'Clearned mUt'h fnlm illhal haspro\'idcd countless hours of funand learning. as \\ell as pro\'ido.:d a

training ground for learning: somemarketable job skills that have en­abled me to always find a jon. Butjust as mainframe computer pro·grammcrs arc dinosaurs. nearlyhaving outlived their usefu lness,could it be that amateur radio hasalso outlived its usefulness? I hopenul. If not then we mu st redefineamateur radio and what benefit tonur socieryzcounrry it can/does pro­vide and then let our <;(lCiety andcountry know!

Detroit radio station \VJR is nowairing An Bell 's show. It's a little100 late at nigh! for me to listen toit. but I might start taping it.

When is 73 going to gel an E­mail address for letters and perhapssending manuscripts for articles?(2)

Amateur radio/computer swapand shops do not advertise as muchas they used to. I remember the lo­cal swap and shops always beingcrowded and people knowing aboutthem substantially before theirdate.BUI not these days.There is just nul

the same levelofadvertisement andpromotion that there used to be. (3)

I have a younger brother whosepast lifestyle may now he causinghim medical problems. He is notHIV positive. but appears 10 be sicktoo often with viral infections andthe like. I am seriously thinking ofbuilding the Bioclcct ri ficr circuit tosec if it will help him. If I do buildone I will lei you know if the re­sults are promising or not. (4)

Keep up the great work. Talliethose chains. keep pushing us 0111 10

do something. keep the editorialsinterest ing and mind expanding.Perhaps it might just get enough.or at least some. people moving!

Hmm, Don. 1m ( /) , for .I O II/e

leaping liberal reason )~'ll fi re ex ,peeling corpora/ions 10 actuallyconsider the!il/ure , It dO(',fll ~ hal'­pen " 'ith peopl(' , corpoTOtiQlts or

/HJ/iticians. Gel real . (2' No .... and

then 1 /001. to see II'hm IlIlS accu­

mulated Ul Desi/?1l73&AOLr o /ll .(3) Ha m radio . a .s 11"('1/ {I .f ollr

hamJests.llas sllllk bt'loll' lhe pllb­

lic a"'areMSS hor;::.on , When willdub.f and /wmfest orgalli::.ers get

lil"t' PR perslm.s ? I got a "'mift'stamlOlUlCemeTl1for a Detm il (kta­

bt'r llamfesl a " ·ee.l aftt' r my Dc/(}­ber 73 came. (-I, The bio-e ,,'on 't

hurt and ("(m id ,,·url. II"l mdeTJ f or\ 'OIIT erra1ft brother. u meno ,.

·" " Ylle . F.D

NWER SR. DIEContinued from page 4

they're not doing either one. In­stead they're passing the hal.asking for more money.

But, let's see what you comeup with. How 's your creativitydoing?

ARRL Wor ried

I've been gelling form tenersfrom the League confi rming thaithey are, at long last. starting toworry about the potential lo ss ofham bands which I've beengloom-and-dooming about inmy editorials for a couple o fyears or so. Naturally they'veused this as an excuse to rattlethei r lin cup. begging for dona­tions. Hey guys, you' re a multi­million-dollar publishing enter­prise. If you need more moneyfor something, raise the sub­scription price for OSl.

As far as donating money forthe protection o f our frequenciesis concerned. it seems to me thatI remember money being setaside for that before . $ 100.000comes to mind. Of course, I'mgetting o ld now and maybe mymemory isn 't as good as it used

to be, but I seem to remembervisiting the lavish League hotelsuite in Ge neva's most expen­sive hotel during an IT U confer­ence. and the fl ying over of di­rectors for part ies, all at themembers ' expense. And hey.wasn't there something about aLeague president who vaca­tioned away a big bunch of thatfrequency-saving money with agirlfriend in the Caribbean?Golly. what was his name? I for­get if I ever wrot e about that ornot

The League letters confirmthat there really is a major prob­le m-that our UHF ham bandsin part icular are in serious jeop­ardy. As I've been say ing . But,you know, I d idn't see any thingin the letters about what theLeague would do to stop the in­coming tide. The demand formore and more satellite andother UHF channels is going tocont inue to grow exponent ially.and we have the League sayingthey need more money. To dowhat, guys? What are you goingto do. send baskets of money toWashington to be doled out (nopun intended ) to Congress?You can't possibly match the

commerc ial lobby money, sowhat will you do if we send youa big check? Party some more?

Yes, I have some good ideason what could be done to helpstem our loss of satellite hands.But first I want to know if (a) asignificant number of our activehams really give a damn; and (b )what the Tech/Novice ham s(now over half of us) think. Domany of them reall y care? Inother words, if the League actu­ally came up with a workableplan, but needed the support o fthe membership, would they getit? However, as far as I can see,other than begging for money,they have no plan of action.

Why should a 75m op careone whit about what happens toour 3300 MHz band? Or even1300 MHz, for that mailer? Isuppose that the 20m Dx ers,contesters. certificate hunters,rag-chewers . the Cw -fo revercrew, and so on couldn't careless what happens to our unused(and presumably unneeded)bands.

Until nearly 1970 the top halfo f 2m was a virtual desert. Heck,when CQ magazine proposedtaking it away and making a new

CB out of it there was almost nofuss. Then along carne repealers.Now we' re willing to fight 10

ho ld onto our precious repeaterhand. BUI hey, why bother aboutour 500 MHz-wide band up at10 GHz? Or a cou ple of unused5 MHz seg ments of the 2300MHz band? People in general.and hams in particular, don'tthink much about the future . Ifthey did they wouldn' t smoke orbe grossly fat. These are denialsof the future consequences ofour actions.

So. guys, if we send youmoney, what will you really dowith it? Will it be like send ingmoney to Washington? Will itjust go in the po t and be thatmueh more to spe nd on currententhusiasms?

The M ich igan I\lirade

Maybe you can remembernot long ago when Michiganhad one of the highest unem­ployment rates in the cou ntry.When the stat e was a national di ­saster, verging on bankruptcy,While I'm not a fan of all theRepublican party planks. the

Continued on page 2 2

HOME PAGE, www. hamboree.org

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TROPICAL HAMBOREE@AMATEUR RADIO & COMPUTER SHOW

ARRL SOUTHEASTERN DIVISION CONVENTIONFEBRUARY 1 • lI, 1997

DADE COUNTY YOUTH FAIR& EXPOSITION CENTERS.W. 112 AVENUE & CORAL WAY (S.W. 24 ST.)

MIAMI, FLORIDA• Sponso red by Dade Radio Club o f M iami, Inc. TALK IN: 146.925

INTRODUCTION TO AMATEUR RADIO DISPLAY' FORUM ON BACK TO BASICS IN THE WIDE WORLD OFAMATEUR RADIO' PANEL DISCUSSION ON INTERNATIONAL SPECTRUM PLANS & THE FUTURE OF AMATEURRADIO' FORUM ON THE FCC AND THE AMATEUR RADIO SERVICE' 200+ EXHIBIT BOOTHS' BDO+ INDOOR

SWAP TABLES' TWO ON·SITE LICENSE EXAM SESSIONS' FIELD CHECKING FOR DXCC AND CQ AWARDS• PROGRAMS BY AMSAT, ARRL, QCWA, DXPEDITIONS, ANTENNAS, PACKET, TRAFFIC, ARES

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73 Amat8ur Radio Today. Janoary 1997 7

FCC Stops RenewalReminders

Have You Appl ied fora Vanity Callsig",n,-,?__

As of October 22, the FCC has ceasedissuing Form 610R license expiration no­tices-reminders to hams that their ticketsare going 10 expire within the next 90 daysand that they must request renewal. The lastnotices sent by FCC covered into February1997, although the specific date was notavailable. A Form 6tOR for renewal must bereturned by mail only to the FCC.

The demise of the Form 6tOR means thathams-whose licenses are issued for 10­year periods-musltake the initiative to re­member the renewal date of their tickets andfile a Form 610. AN FCC spokesman inGettysburg says the Commission hopes 10have a Form 610 available soon on theWorld Wide Web to permit on-line renew­als.

From The Repeater, official newsletter ofthe Alamo Area Radio Organization, SanAntonio TX.

CIRCLE 69 ON READER SERVICE CARD

8 73 Amateur Radio rcasv » January 1997

The FCC will not start making any grantsfor first-day filers until all day-one applica­tions have been entered into the FCC's com­puter. Then applications will be processedrandomly from among those in the first-daypool.

The number of hams taking advantage ofGate 2 has been less than anticipated. Asof September 25, 1996, the FCC had re­ceived 5,297 Gate 2 applications. First-dayvanity filers totaled 4,527, a number thateven surprised the FCC, which had beenexpecting a larger flood of Gate 2 filings. TheFCC said 4, 188 paper applications and 339electronic applications we re received thefirst day. Another 770 applications, mostlypaper, had showed up by Wednesday,September 25. Slightly more than 7% ofthe applicants used the FCC's new lyinaugurated electronic filing system.

QRN.

~b"tlo• .-.-I>

ProYO.UT.-

• •

Anlenllas West0ftHr _liM f. 9

80 1_373 ·6425 I.',.:"

Num~r8 onyour FHdbacl< o:tlrd

Among the major headaches for the folksin Gettysburg are applications that containillegible information. FCC personnel havebeen instructed to skip over requestedcallsigns they cannot decipher. Also, someelectronic f ilers have been sending theirpayments to the wrong Post Office box inPittsburgh and using the FCC Form 159designed for use by those filing on paper.The FCC said that contrary to instructionson the electronic application form, electron icfilers should not forward a copy of their li­cense to the FCC by mail. FCC personnelhave no way to match up licenses with ap­plications, and they don't need the licensecopy to process the application.

The FCC said that some applicants ap­parently have had second thoughts aboutchanging their callsigns and have contactedthe FCC to pull their Gate 2 paperwork. TheFCC says that cannot be done. Those is­sued a vanity callsign who decide they likethe ir old callsign better will have to pay an­other $30 and reapply under Gate 1.

If the FCC is unable to grant any of yourvanity callsiqn requests, your application wittbe dismissed, and the FCC wi ll not ify you tothat effect. But the Commission will not re­turn your $30 until you request a refund inwrit ing.

Excerpted from Harmonics, October1996, official newsletter of the SouthJersey Radio Association.

Alaskan Hams SizzleDuring Forest Fires

It's a sign of how times have changed thatham radio was not even considered as acommunications link by Emergency Man­agement, because of the wide use of cellu­lar phones, during the recent disastrousforest fires in the Big lake area of Alaska.The Amateur Radio Emergency Service Netwasn't part of the scenario. Hams were usedfor some of the communications during theMiller's Reach fire, but only after going tothe Emergency Man agement people tomake their availability known.

Communications ground to a halt whentelephone lines and cellular phone frequen­cies were so overloaded they jammed. Somany people were trying to get in touch withloved ones in fire -threatened SouthcentralAlaska thai the local cellular companies hadradio stations begging people not to use theircellular phones: land lines we re taking aminute or more just to come up with a dialtone.

Hams to the rescue! "My XYL. who is nota ham, and rarely pays attention to what Iam listening to or doing on the radio, wastotally impressed with the number of hamswho suddenly came from nowhere to be just

about everywhere," wrote Bob NL70P, edi­tor of Mara News. ~We must continuallymake our communit ies aware of the impor­tance of amateur radio during a disaster. Weneed to make better use of the bands wehave, and encourage that use so we canretain those bands."

Condensed from an editorial in MaraNews, the offic ia l newsletter of theMatanuska Amateur Radio Association,Wasi lla, AK.

.The Boy and the Froy-

A boy was crossing a road one day whena frog called out to him, 'Kiss me and I'llturn into a beautiful princess."

The boy picked up the frog and put it inhis pocket.

The frog said, ~If you kiss me, I'll turn intoa beautiful princess, and I' ll stay with youfor a week."

The boy took out the frog, smiled at it, andreturned it to the pocket.

The frog cried, "If you kiss me and turnme back into a princess, I'll stay with youforever, and do anything you wa nt!"

Again, the boy took out the frog, smiledat it, and put it back. After a long pause, thefrog asked , ~What is it? Why won't you kissme?"

The boy answered, ' t .ook. I'm an ama­teur radio operator. I don't have time for girl­friends, but a talking frog-hey, thaI's cool!"

Lifted from ARN$ Bulletin. October 1996.

Learn More AboutQRP

Founded in January 1994, COC bringsamateurs interested in low power together,and endeavors to expand their interests andgive them a forum in which to discuss prob­lems and accomplishments. Besides its bi­monthly meeting for local members, COCpublishes a bimonthly newsletter, The LowDown. The Low Down contains technicalartic les, product reviews, member news,upcoming activ ities, and an activities calen­dar. CQC membership is open to anyoneinterested in QRP.

In eastern Colorado try the Colorado ORPClub net every Monday evening at 8 PM onthe 147.225 repeater in Golden, and on the145.1 60 machine in Colorado Springs. Theyalso use 146.445 simplex. On HF, calt "COCOC~ at8 PM on 3710kHz (the national 80meter QRP frequency).

For an application form, send an SASEto Mark Meyer, 14153 West First Drive,Golden CO 80401. Membership dues are$10 a year, including a subscription to TheLow Down.

Excerpted from ARNS Bulletin. October1996. III

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Number 10 on your Feedback card

The ScopeMixerAn adventure in ham radio systems integration .

Dave Evison N6GKC153 Park Avenue

Palo Alto CA 94306

Monitor

U S I ~

Fig. 1. Scopes tsxer Rany, e1SWR o -«.

The ScopeMixer was designed to usean MFJ (or Autek) SWR Analyzer as aloca l osc ill ator working either 1 MHzabove or below the RF. Harm onics andother spurious emissions are measuredby es tablishing an IF refe rence level atthe carrier freq uency, then tuning the lo­ca l oscillator up or down from the car­ner frequency and observ ing signalsthat develop an IF of I MHz. For ex­ample, if a reference carrier of 7 MHzhaving a second harmonic component isconnec ted to the ScopeMixer, It willprod uce an IF of I MHz at 6 MHz and 8MHz (re ference frequency) and at 13MHz and 15 MHz (the second har­monic). The amplitude of the harmonicresponses whe n compared to the ampli­tude of the re ference carrier will deter­mine their relationship in decibels (dB).

To understand the input circuit referto Fig. 1. The values of R I throu gh R4were calculated to deliver 25 millivoltsrms to the base of the 2N2222 when 707mil livolts (.707 vol t) rms is app lied atthe RF input. While the 2N2222 in thisconfi guration will work with levels sig­nificantly greater than 25 mY at its base, itbecomes quite nonli near. Main taining 22

,- - - - - - - - = =~IOTunii

~"'--~.fThe ScopeM ixer is a simple applica­tion of a heterodyne mixer. It convertsthe RF input to a I l\.1Hz intermediatefreq uency, which is well within thebandpass of the ancient oscilloscopes.While any frequency between about550 kH/. and 1600 kl- lz can be used forthe IF, I MHz simplifies setting the lo­ca l oscilla tor when measuring harmonicand other spurious products.

How it works

market), a secondhand MFJ SWR Ana­lyzer used as a local osci llator (aboutS40-but you may already have one ofthese handy litt le devices). Now that'sreal ham engineering !

The ScopeMixer is a good example ofrecycling older technology that is rarelyused today: the wave analyzer. Thewave analyzer has bee n supplanted bythe spec trum analyzer in most commer­cial laboratories, but it's still simple, in­expensive, and provides an impressivemeasurement capability.

The design criteria for the Scope.Mixerwere to keep the cost and parts count lowand use only read ily available parts . Theresult is a straightforward bipolar mixerusing a 2N2222A transistor (Fig. 1).The RF is applied to the base, the localosci llator to the emitter, and the IFtaken from the collector- it reall ycouldn' t be simpler-and with 2N2222transistors selling fo r less than 10 cents,it couldn' t be muc h cheaper. There is noIt-: transformer. Instead, an old broad­cast " ferrite loopsrtck'' is used. The unitdraws less than 10 mA and req uiresonly a 3 volt supply (a co uple of AAbatteries in series).

RF InpY1(-707 VRMSI Al

Fig. I . ScopeMixer schematic.

10 73 Amateur Radio Today· January 1997

How would you like to adjustyour antenna tuner while yourrig is terminated in a dummy

load? (Your final amplifier and fellowhams sure would!) Or how about mon i­toring your SS B signal and chec king thepeak enve lope voltage for clipping andcrossover d istortion? (Wow, talk aboutgood operating practice r) And woul dn'tit be great to check the rise and dec aytime of your CW envelope and be ab leto see those chirps or clicks? Or howabout bei ng able to detect and measureharmonic rad iation and other spuriousprod ucts (just like the big guys)? Well ,even if you' re sitting on a very thin bill­fold , you can manage all of this- andmore-s-with a ScopeMixer System.Whil e it' s primitive by commercia lstandards. it can provi de you with a ver­satile measurement sys tem at very lowcost The ScopeMixer will empoweryou (without spectrum analyzers andother professional laboratory instru­ments) to produce superior, well-testeddesigns.

The ScopeMixer System is an ex­ample of ham rad io systems integrat ion:a couple of simple circuits containingonly one active component (a 10-centtrans istor). an inexpensive 40-year-o ldkit oscilloscope ($15 at any ham tlca

MFJ-283, MFJ-285,MFJ-285L, MFJ-285W,MFJ-287 or MFJ-287L

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Order MFJ-285/MFJ.285L for teOM,Yae su, Ali nco, Radio Shack and Standard;MFJ·287IMFJ·287L for Kenwood; MFJ·283 L Connedorolwfor spli t plug Ali nco; MFJ.285W for IC-W2A. available· order LIl'UKkL

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First-rate electret m ic e lem ent and fullsize speaker gives superb audio on transmitand recieve. Earpho ne jack, PTT, light­weight retractable cord. Gray. 11/4x2x3 in.

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VertlcallnpIA

LocalOsciIlalor

AFln

\~-

identified reference level) you will beable to re ly upon the bask accuracy o fthe oscilloscope's vertical deflectionlinearity-which in the case of the o lderkit scopes works o ut to be abo ut 5%.Overall accuracy is cumulative and fac­tors suc h as local oscillator leveling,gai n-bandwidth product of the 2N2222.no ise. etc.. all contribute. But. after all.the Scopextixer is for ham applications.not rocket science.

To mi nim ize identified no ise and gainproblems. mcucurcrncnts ...hould he per­formed on the X I range and utilize thelarge C RT deflec tion (4 to 5 inches ). Inthis manner, deflection accuracy will helimited to the vertical de flection linear­ity and the gain co ntrol wi ll he closer tohalfway on.

Usin g the scope atrcnuatc r to provide20 dB gain (for example. establishing areference level on X I O. then se lli ng thescope to X I for mcasurmg uttcnua­no n-e-eq uivalent to 20 dB gain) is notreco mmended because norse compo­nents increase dramatically as the var i­able gam control IS se t a t or ncarmaximum. A second reason for not us­ing the SL'0 PC auc nuator in the measure­mcnt scheme is that above I MH z thescope's internal ancnuator compensa­tion adjustments great ly infl uen ce theactual gain/attenuation between steps.and among the three kit scopes used furthis proj ect. all three had severel y mal­adjusted attcnuator compensation .

Oscilloscopes with wider bandpasscharacterist ics do not work well with

the Scope Mixer system as they arcse nsiti ve to unwanted sig nals appear­ing in the IF o utput (local osc illator.RF fundame ntal. erc. j . If a widcbandscope is used, an IF transformer wi tha tuned pnmary and secondary willbe- req uired . The lo w cost o f the o lderosci lloscopes. and their performance

, ScopeMixer

'---r------J 0""". .......:::::::.L-I~LO. ln

~ Ieasurements

A pattern for a calibration overlaygrid is shown in Fig . 3. Using this over­lay grid will simplify measurements andmerease accuracy,

Make an overlay from the magazinepattern by copying the image onto anoverhead transparency sheet. Then cutthe over lay o ut and place it on the faceo f the cathode ray tube . Align the centerhorizontal line o f the overlay grid withthe oscilloscope trace .

The Scopextixcr will all ow you tomake attenuat ion measurements in dcci ­bets (dB). Since dB measurements arcrelative measurements (compared to an

Making a calibration over lay grid

L1 and L2 arc RF transformers madeby windi ng secondaries over o ff-the­shelf Radio Sbackt" 100 IlU RF cho kes(RS #273- 102). Before winding the sec­ondary onto L2 (30 turns #20 enam­eled). it's a good idea to put a layer o fmasking tape over the wi nd ings of thechoke. T he primary (L1 A ) is fou r turnsof stranded. insulated wire (about #20 ),

The Range/SWR Uni t shou ld he en­closed in a suitable chassis box for bot hshielding and prevention o f RF hums .Use a good qua lity wafer-type switch(do not usc a toggle-type switch) andensure the switc h IS a brenk-before­make type .

RangelSWR Unil construction

familiar with ug ly construction. checkthe ARRL Handbook (it's actually listedIn the index of some Issues under"Ugly" ). The accompanying photosho ws a prototype ScopcMixermounted in a small metal 00.\ (note tha tugly construc tion was re tained ).

Fig . -I. Scopes tsxer Rallgf'lSWR Ulli, system setup,

Isv'

.~

to 28 mY at the base will enable theScopcjvlixcr to display levels as low as-30 dB (refe renced to the input levelI.

The pot will allow fi ne-tuning to the de­sired 25 mv when levels slightly greaterthan 0.707 Y rms arc applied to theScopclvtixcr Rl- Input. I recommend thatthe pot be kepi full-on and that the inputto the mixer he trimmed using the rangecontrol pot on the RangelS WR Unit.

The Range/SWR Unit samples the RFsource to he monitored. It accommo­dates RF levels from IRO mW to over100 W. It also includes an antennabridge for performing "stealth" antennatuner adj ustments . In Fi~ . 2. you seethat the RF sig nal to he monitored/mea­sured is sampled inductively by LI NLI B. With S I in the rune posit ion. theRF source is terminated in an externaldummy load. and a small sample of theRF energy is used for antenna bridgeexcitation . R I , R2. R3. and the antennasystem are con fig ured as a simple an­tenna hridge-and the Scopcbfixe r IS

used a.. the detector. Using the osclllo­SCOIX readout of the Scopcxtixcr providesgreat sensitivity. smoothness and resolu­tion . L2NL2B transfer the signal dcvel­oped hy the unbalanced condition of thebridge to YRI which provides level con­trol to the Scopcstixcr, VR I functions asthe RF range control. With S I m themonitor po sition. the unbala nced bridgesignal is fed 10 the ScopcMixcr throughL2A/B a nd YR I. Th is signal is usedas both the culibrntion level for SW Rmeasurements and reference level forattenuation measurements .

I'm a grea t fa n of Wes Hayward and hisUgly Construction. and my ScopcMixe ri ... an excelle nt cand idate . If you're not

. ,~

=

Scopehlixer construction

Fig . J. Catibrauon overlav grid,

12 73 Amateur Radio Today · January 1997

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·20 dS

-20 dBdB

-20 dB

in this application . jusufy theirdedication to the system.

For amateur applications. measure­ments are generally made while per­forming adj ustments for peaking ornulling . For example. you've just fi n­ished a QRP rig and you want to checkfor. and ir necessary attenuate. harmon­ics and other spurious products. In thiscase your concern is not the accuracy orthe harmonic level. but rather to be ableto detect it and reduce it as much as pos­sible. In this case the ScopeMixer willbe able to display the spurious signal.You peak the display using the local os­ci llator, and [hen make adjustments tothe rig. or substitute new components inthe circuit. to reduce the level of thespurious signal.

Tbere is nothing particularly criticalabout setting up the system. Use highquality RG 58U coax cable and BNCconnectors. and ensure that excessiveRF is not applied to the RangelSWRUnit. The power level should not exceed100 watts. Interconnect the equip mcntas shown in Fig. 4. and set the equip­ment as specified under "EquipmentSetup."

In adjusting the loopstick, start withthe slug in about halfway, Apply the lo­cal oscillator frequency (approximatelyI MHz above or below the RF input sig­nal); set the pot on the ScopeMixer fullyclockwise and adj ust the RangclSWRUni t pot to the level of RF to be applied.

Key the transmitter and apply a CWsignal to the system. Fine-tunc the localoscillator to produce maximum verticaldeflection and stabilize the display.Adjust the focus control for best trace.Then adjust the variable gain and verti ­cal position controls to set the wave­form peaks to the reference levels(Fig. 6).

Fig . 5. Although the peak-to -peak amplitudeof this waveform measures greater than -20dB. "subtracting the fuzz" results in a moreaccurate measurement of -20 dB.

/'llOto A . A peel inside IIII' SmpeMixer.

Remember to subtract the fuzz. RemoveRF power from the system. Remove the5(K) resistor and reconnect the tuner and an­tenna system. Key tbc transmittcr and adjustlhc tuner fo- minimum deflection,

Equipment setup

Oscilloscope front panel control settings:Vertical uncn uator: XIVariable gain: 40Horizontal sweep: 100 kHzHorizontal vernier: XOHorizontal gain: 20Sync selector: Im +Inte nsity and focus for best trace.

Local oscillator (LO) (MF) or AutekSWR Analyzer) settings:Frequency: I MHz below the RF

source to be measured.

Note the frequency of the local oscil­furor and compare it to the frequency ofthe applied RF. lf the frequencies arcseparated hy more than I "'1Hz. adjustthe slug further into the coil ; if sepa­rated by less than I MHz. adjust theslug out of the coil. Repeat this processuntil a I MHz +11>% IF is achieved.

To check the SWR function of theRange Unit and adjust the tuner forminimum SWR. interconnect theequipment as shown in Fig. 4. Set the

R,mge/SWR Unit to the tunc position.then rerno vc the antenna tuner from theRange/SWR Unit. Key the trunsmiucrand apply a CW signal. Fine-tunc thelocal oscillator. and peak and synchro­nize the IF display. Set the waveformpeaks at the reference levels Wig. 6).Remove RF power.

Connect a 50U non-inductive resistor10 the tuner port. then key the transmit­ter. The peak-to-peak display should heapprox imately 114 inch or less (FiJ,.:. 8 ).

ScopcMixer settings:RF input pot fully clockwise , power

switch on.

RF rangclSW R unit settings:Set tunc-monitor switch to monitorSet range pot according to the amount

of power to be sampled, If possibleIimitthc RF level for initial settingsfrom 5 10 10 walls.

MeasurinR harmonics and otherspurious products

Fi rst. establish a reference level at thefundamental carrier frequency being mea­sured, Once set. the vertical gai n controlshould not be readjusted until all mC3-"UTC­mcnts have been made and n oted. The lo­cal oscillator is then adjusted above andbelow the carrier while watching thescope for intermediate frequency re­sponscs. Harmonics, of course. will bemultiples of the carrier frequency. burother spurious responses will not. Once aresponse is detected. peak the signal usingthe local oscillator, and read its amplitude(in dB) from the calibration grid. The fre­quency of the spurious signal is deter­mined by adding or subtracting I MHz(depending upon whether the local oscil­lator is opcnuing above or below the spu­rious response).

NOll' : HeIOIl' -20 d B . noise and thewidth of the trace s ignifican tly limitaccuracy . lVirh ex perience . von canimpro ve such measnremem s by..subtracting th e jil:':' '' f rom themea.\"II rement (F ig . 5 ).

- I dB

-6~

B

Reference

Reference

~

-+-t--+-+---r--t--r~"---I

-2'l.@

;:I

-10

Fig. 6. Reference level ,

14 73 Amateur Radio Today. January 1997

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Examining keyed carrier waveforms

Measuring SWR

Monitoring modulation is limited toobserving the modu lation envelope, bUIa great deal of information can be gat h­ered in this manner- single sidebandpeak envelope voltage cl ipping andcrossover distortion can be observed .Refer to the ARRL Handbook for moreInformation on these parameters.

Monitoring modulation

PholOB . Scopestixer system wim scope ...

With the transmitter in the CW mode.key the transmitter by sending a seriesof evenly spaced dits and adjust thehorizontal vernier to o bserve the keyedenvelope.

Remove the antenna tuner from theRangclSWR Unit, then set thc RFRangclSWR Unit to the tunc position .With the transmitter in the CW mode,key the transmitter and fine-tune the lo­cal oscillator to peak the oscilloscopedisplay. If the rig is SSB-only. set it totune. Adjust the Range pot until thepeak-to-peek signal is set to th:: rcfereocclevels on the calibrdlion overlay grid Theoscilloscope vertical position control may

rho/a C. ... and without the scope. CIRCLE 186 ON READER SERVICE CARO

73 Amateur Radio Today · January 1997 15

-: Reference <, Range/SWR Unit Parts List

.: ~~ R1 ,R2,R3 51 n1 /2W

I \VR1

600 Q Linear..,," Composition-

·2" , -20 dB DPDT Wafer7"\ S l Switch (break-~ "\~ before-make)

• d -10 dB 100 ~F RFC

\ -6 " B IL1B, L2A (Radio Shack

- dB 273-1 02)

-. / 4 turns #22

L1Ainsulated

wound over<, Reference .> LlB

30 turns #26F ig. 7. -20 dB.

ename l

also require adjustment (0 position the wave- (Fig. 8). Keep in mind that you need (0 sub- coveredwound over[OI1U on the calibration grid (Fig. 6). Once tract the fW7. (Fig. 5). Remove RF powerL2A (coverset remove RF power and connect a son from the system. Remove the son resistor L2B

non-inductive resistor to the tuner port. Key and reconnect the tuner and antenna system. L2A with athe transmitter. 'The peak-to-peak display Key transmitter and adjust antenna tuner for layer ofshould be approximately 114 inch or less minimum peak-In-peak display on the oscil- masking tape

loscope. A matched condition will result in before windinga peak-to-peak display of approximately L2B)l/4 inch (Fig. 8). !l!l

ScopeMixer Parts List

Rl 75 Q

R2

R3, R7

R4,R6

910 Q

51 Q

1 k

Reference

R5 4.7 k -t B

VR1200 Q LinearComposition

B

C1, C2,C3 .001 ~F-20 dB -20 dB

C4 0.1 ~F. t B -1 d

Reference

-6dB

Fig. 8. SWR null,

BroadcastFerrite

Loopstick'l1

C5

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16 73 Amateur Radio Today' January 1997

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73 Amateur Radio Today ' January 1997 17

g rou nd to ke y a solid -Slate e xci te r.Some so lid-S late tra nsmi tte rs switcha positive voltage in th e exciter toground for keying a nd refer to it as" cathode keying ." That is likely amisnomer because the o n ly catho de sare p robably ca thodes of semicon­duc to r diodes. Ju s t so we can allsi ng from the same hym na l. I willrefer to switc hing a posit ive voltageto g ro und as " ca tho de keyi ng : '

The ke ying speed is variab le fromle ss tha n five to about 30 words perminute with a sing le fron t panel co n­t ro l. Eq uatio ns are g ive n for selec t­ing parts to al lo w higher ke y ingspeeds. The wei g ht is adjusted inte r­nall y and is ma intained for allspeeds . A front pane l to gg le s wi tchis prov ided to produce con tinuous" key-do wn" for tran sm itte r tu n ing .The op tio na l si de tone ge nerator canprov ide about 100 mW of audio tod rive low impedance phones or aspeaker. Th is power is adequate fo rm ost situations .

T he functional b lock diagram inFig. 1 shows ho w three monc stabl emul t iv i-brator p ul se g e nerators a ndlog ic e lem ents ca n be used to p ro­d uce the ke yin g wave forms . O nemult ivibrator ge nerates the dash pe ­ri od . the second gene rates the spac eperiod . and the th ird ge ne rate s thedot period . The space- to-dash ratioa nd d ot - to -d ash rat io o f the keyerarc adj us ted inde pe nd e ntly . T he se­lected rat io of dot/das h/space ismai nta ined for keyi ng speeds from 5WPM to 30 WPM . T he monostable

An inexpensive flexib le keyer canbe buill with two 4000 seriesCMOS ICs ( 0 genera te indepen­

dently adjustable self-complcting dotsand dashes. The keyer can drive an inex­pensive MOSFET cathode switch thatwill key anything from a solid-state QRPrig to a kilowatt tube final. The keyerincludes an optional sidelone generatorthat can be used as a code practiceoscillator while you learn to use the keyer,

The keyer described generates akeying waveform whose wei ght can beadj usted to suit your preference. Th isweekend project uses no critical partsor unique ICs, so, depending on thestate o f yo ur junk bo x, co nstruc tioncosts can be low. Equations arc givento allow modification of the design tofit the parts you have.

The keyer generates a keying wave­fonn that drives a MOSFET transistor tocathode- ke y a tube type tra nsmitteror switch a positive voltage to

Fig. 1. The keyer is built around monostablemuhivibrators and combinatoria l logic ,

Fig. 2. A monostabte meltivibrutor huitt withCMOS JIm these crith'al 1l'(Il'ejimllJ .

UnitE/ +V pe riod Speed

sees.1.0 00 .042 30.884 .050 25.7 6 9 .063 20

.6 6 7 .08 3 15

.571 .125 10

.507 .25 0 5Table 1.

and the slowest speed occurs whe n ETis near Y.

l ll.

The duration o f the unit ti ming period .whieh is eq ual to the time o f a do t orspace, is determined as follow s: Thestandard word "PARIS," requires 4g unitperiods (dot pe riods). T here fore, at 30words per minute (ha lf a word pe r sec­ond) there arc 24 unit periods per secondand the durat ion of a unit period is abo ut0.042 seconds . To produce a dot pe riodof 0 .042 seconds rcqurrcs an RC o f0.029 seconds (0.042 x 0.69). A standard3:I dash period is O. 126 seconds and theRC is 0.0 87 seconds . T he dot and spaceare varied with respect to the dash tochange the keying weight. T he va lue ofE!+V for various keying speeds is givenin Table I .

T he kcycr shown in Fig. 3a use s twoC~tOS ICs: a CD400 1 quad NOR gateand a CD4009 hex inverter. V IA andU21\ ge nerate the dot p ulse, V IB andU2 H generate the dash pulse , an d V ICand V2C ge nerate the space pu lse . Thedot period is determi ned by C2 x (R2 +R3) and ~; the dash pe riod is deter­mined by C3 x R5 and ET: the space pe­riod is determined hy C6 x (R9 + R lO)and E

T. The dot pu lse or dash pul se is

triggered with the positive vo ltageswitched thro ugh the key. The voltageo n the arm of the key is ob tained fromthe AND formed by D5 and 0 6. Thekeyin g wavefo rm for the gate of QI isohtained by ORing the dot and dashpulses. T he trigger for the space ge nera­tor IS obtained by differentiati ng thekeying waveform with C5 and R8, andinverting the nega tive transit ion withU2E. The keying waveform is in vertedby U2 D to gate the sidetone ge nerator

T iming Voltagevs.

Keying Speed

t = -RC x Ln( I-Vn / EET) = -RC xLn(I -O.5VDD/ET)

t = RC x 0.69 whe n ET equals VDD

the inverter and drives the inverter 's in­put below VTIt • The inverter's ou tputgoes "high" and holds the " B" input ofthe NOR ga te high unt il C, chargingthro ugh R toward I:-'~ , reaches VTH .

While the inverter 's output is "hig h," the" B" inpu t to the NOR gate holds the out­put low and triggers to the "A" inp utha ve no effect. The stahle state of themultivibrator is both inputs o f the NORgate "low" an d the input of the inverterheld "high:' The unstable state, or tim­ing state, has the output of the NOR gatelow, C charging to ward ET . and theinverter outp ut high .

T he transition of the NOR's outp utfro m +V to zero will try to dri ve the in­put of the inverter nega tive (belowgro und) when ET is less than + Y. TheIe's input protect ion ci rcuit limits thenegat ive voltage to one diode drophelow ground. On the positive transitionof the NOR's ou tp ut, the positive swingo n the inverte r's inp ut is damped to E,by the diode across R.

The vo ltage on the input of the in­verter rises toward ~ at a rate controlledby R and C. T he instantaneous voltageo n the gate is:

T his can he rewritten in terms of t andRC :

V = F. x ( l_ e-Vl!c), ~

-tiRC = Ln( I-Vi ET)t = -RC x Ln( I-Vi ET)

where t = time in secondsR = ohmsC = faradsLn = the natural logarit hmV,. = the instantaneous voltage across

the capacitorET = the speed contro l voltage

W hen all three pulse ge nerators havethe same VTH and E

T, the pulse genera­

tors maintain their ratios as ETis variedT he minim um pulse period (hig hestke ying speed) occurs whe n ET is +V

W hen the gate voltage " , reaches VTH

•

the output of the inverter switches. Sinceeach pulse ge nerator's period. ends whe nVc = V TIl = O.5VDD ' the time of the pulsecan he written as:

.,

®C :::: D

~

./

II I__.

W

vJ~WI 1------©

®

®

@

®

mu ltivibrato rs used arc non­rc triggerahle. Once a pulse is init iated.subseq ue nt triggers d uring the pe riodof the pulse have no effect on the pu lsed uratio n.

A typical mo nostahlc multivi bratoris show n in F ig. 2 . T he lim ed period isdetermined by R x C. VTIl (a character­istic o f the [C ), and Er, the lim ingvo ltage contro lled by the "Speed Con­tro l." The threshold. V l'l l ' of 4000 se­nes CMOS IS betwee n 0.45Vno andO.SSYDO" VDD is the supp ly vo lt age +Y.While the match of threshol ds fro mone chip to another may vary 201%,_ th ematch of units within an Ie IS veryclose. T herefore , the inverters arc allwi thin one Ie to e ns ure tracking o f theperiods as ET is varied. Each of them ult ivibrators uses o ne sec tio n o f theCD4009 hex invert er. The ICs can heeither AE or BE versions: use whateveris available.

In a NOR gate, the output is "low'(zero vo lts) whe n ei ther input "A" or" 13 " is more positive than VTH ' and is"high" (+V) when both inpu ts arc morenegative tha n VTW In Fi~. 2, the resistorat the "A" input of the NOR gate holdsthat input " low" until a positive triggerdrives it above VTIl' The " B" inputwhich is connected to the output o f theinverte r IS "low" because the positivevoltage, ET , at the inverter 's input IS

above VTIl ' When a positive pulse is ap ­p lied to the "A" input of the NOR, theou tput goes "low: ' Thi s negative transi­tion is coupled thro ugh C to the input o r

18 73 Amateur Radio Today · January 1997

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and AND'd with an output from thespace pulse generator with 0 5 and D6 toproduce the voltage for the arm of thekey; the diodes 05 and D6 clamp thearm of the key low during the key-downand space period. The arm of the key re­turns to +V only after the end of the dot/dash and space periods. Therefore, onlyafter the dot/dash/space period ends isthere a positive voltage available at thekey to provide a trigger or rc-rriggcr foreither the dot or dash with a key closure.R7 provides the pull-up for the diodeAND and in conj unction with C I andC4, filters out the spike that can occurduring the transition from key-down tothe space period. The capacitors C l andC4 also filter any RF that may be pickedup on the leads from the key.

The side tone oscillator, shown in Fig,3b as U I D and U2F, is an astablemulti vibrator that oscillates at a fre­quency determined by Rl4 and C8. Theoscillator is gated "on" when the outputof U2D applied to U I D (via point A) iszero. The values of C8 and Rl4 shownin Fig. 3b generate a 720Hz square waveduring "key-down." To lower the fre­quency increase R I4 or C8. The outputcurrent capability o f U2F is in the rangeof 2 rnA which is fi ne for dri ving CMOSgates or other high impedance loads, butis inadequate for low impedance loadslike phones or a speaker. A simpleMPF930 source-follower easily pro­vides lOOmW of audio power to an 8ohm speaker or phones.

For example, the typical MPF930 hasa threshold of about 3V gate to sourceand saturates at O.2A with a gat e tosource voltage of about 4V. Rl5 controlsthe input voltage to Q2. When the inputis 3V or less the source voltage is zeroand when the drain cu rrent is O.222A thegate to source required is about 4 .2Y.With O.222A flo wing in 8 ohms, thevoltage across the speaker is about 1.8V.Therefore the peak voltage at the gatemust be 1.8 + 4.2 or 6 volts. To obtainlOOmW of audio into an 8 ohm speakeror phones requires a power supply of atleast 6Y. A different speaker resistanceor power output would require a differ­ent supply voltage. The current drawnfrom the supply is in the range of O.25Awhich warrants an AC powered supply.When the supply voltage is more than6V, a resistor Rl6 in series with thespeaker will limit the maximum currentunder full volume. With an 8V supply,

LSI

6

2

v

that can switch +30 volts . Whil e thedrain current is rated as l A , th isspec ification is not very meaningfulbecause therma l co nditions limit thecurrent carry ing capaci ty to so me­thing in the range o f O.5A in a 122°Fam bient tempe rat ure . The MPF960can switch +60 volts . Either theMPF930 or the 960 will be sufficientto key most solid-state exciters. Thedrai n satura tion resistan ce is about 10ohms which results in a drain tosource voltage of about O.5V whe ndrain c urrent is 0.5A. and about 0.25Vwhen drai n c urrent is 0.25A.

Keyi ng a vacuum tube power ampli­fier requires the key ing transistor toswitch voltages suffic ient to c ut offthe tube and be capable of carryingthe peak cat hode c urrent. A typicalkilowatt tube final will be cut-o rr with+I00 volts or so applied to the cat h­ode and cathode peak: curre nt will beless than IA. Fig. 4 shows how theMOSFET can be used to cathode keya high power amplifie r stage . E" CI inFig . 4 is a positive voltage su ffic ientto cut-o ff the keyed tuhe for "ke y-up"condit ions, that is, when Q I is notconducting. Of course, E' IOcan he ob­tained with a resistive divider if needbe. The va lue of the resistor betweenthe cathode and E,./o ' or Tbe venin'seq uivalent source resistance of the di­vider. is arbi trary : it must supply thec ut-off volt age at ze ro c urrent du rin g"key-up" and limit the current from E </u

during "key-down ."An Ncchan nc l power MOSFET for

QI is an idea l sw itch in that drivepower is prac tically nil even thoughthe drive vo ltage must sw ing fromground to near ly + 10V. The pack agestyle essentiall y determines the powerthat the device can dissipate without a

CBR13 +\1

"13 R14

Q<, II -,14 15

I

/ RI5 Rl12

VOLUlD U2F I rm

n "

A

Fig . .lb. The sidetone generator is up/iollal .

9 +

RI ,"

, Ul~C1

7 . :;.::: C2 or

+ E,

2 'A a "'"0CATHODE

" '< R2 l eaOOT

OOT <02

DASH 03 """ 01..4 ~

51s R5

tNE

" oa /

" ~"s

-' ET" UIB, • +

+ee05 Y RIl

• •~

ET

Rlt~':t :: ::: ( 506

~"'EO

/ • n "• >;- ninc

*" -, •ET 07 I""""

6;±ee

~C71 , •RIO V +

esSP'"

Fig . 3a. The "eyer uses garden-variety CMOS ICs .

R 16 should he 13 oh ms hut with a 12V he done safely with Q I in the keyer,supply. it should he 27 ohms . If the h UI i f a vacuum tuhe final is to hesidetone generator is not desired . delete ke yed. prudence and safety dictatethe pa rts marked * in Table 2 and tie the that Q I should he located near theinputs o f U l D and U2F to either +V or cathode of the keyed stage 10 keep theground. hi gh vo ltage out of the keyer and

T he elec tri cal parts list for Fig. 3a away from the ope rator.and Fi~. 3b is given in Table 2. Most The choice o f Q I depends on the re-o f the parts are avai lable from Rad io quircmcnts of the transmi tter to beShack 1M , and those that arc not in the keyed. The MPF930 is a TO-92 N-retai l catalog wi ll be ordered b most channe l enhancement mode MOSFETyRadio Shack stores from Radi o ShackUnlimi ted. If your c upboard is hareand your local sto re wan ' , order fromRadio Shack Unlim ited (RSU).equivalent part s can be obta ined fromalmost any industri a l elec tronic s dis­tributor. For exa mple, Digi -Key, POBox 677, Thief River Fall s, MN5670 1-0677 : toll -free order number is(800) 344-4539.

Keyin g a solid-state transmi tter in ~

volves switching a re lativel y low vo lt­age so the "cathode" switchingtransistor can he safely located in 'hekeycr. Switching 48 volts or less can

20 73 Amateur Radio Today· January 1997

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73 Amateur Radio Today. January 1997 21

RSU

27 1-13 35

RSU

271 -092

RSU

271-1131

Number

272· 126

272-1069

272-1435

272-1065

272-1435

2 76-11 22

276-2401

current, the saturated dissipation is di­rectly rel ated to Ros . Therefore, alarger die has lower power dissipationfor a given current. A MTP2N20 dissi­pates I .SW when the drain current islA, the MTP5N20 dissipates IW, andthe MTP8N20 dissipates 0 .4 Walts .T he junction temperatures for thethree devices would be 11 2.5°.62.5°,and 25° respecti ve ly. Holding thejunction temperatures to under 150°limit s the operating ambients to 38°C,87.5°C and 125°C respect ively,

It goes without saying thatMOSFETs with higher current ratingshave larger dice and cost more thanthe lower current devices. A moderateheat sink similar to Radio Shack PIN276- 1363 with a thermal resistance of30 ohms is a cost-e ffective solution tousing lower current devices in higherambients. For example. the MTP2N20has R

JCof 2.5°C/W and with a 30 ohm

heat sink the j unction temperaturerise, when switching IA, is (30 +2.5)OC/W x 1.8W = 58.5°C. whichmeans it can operate in an ambient of91.5°C. The MTP5N20 has RJC of

Description

100 pF ceram ic

0 .1 ± 10% J.l. F fil m

2.2 ± 20% )1F electrolytic

0 _01 ± 10% IlF

2.2 IlF e lectrolytic

1N4148 swi tching d iode

8il speaker: see text

see text

MPF9S0 Ncchannel MOSFET

lOOk ± 5% 1/4W

Electrlcal Parts List for Figs. 3a and 3b

Circu it Symbol

Cl ,4,5

C2, 3 , 6

C7

ca'ca01,2,3,4, 5 , 6 ,7

LS I '

01

02

R1, 2, 4, 6 , 8,10,11, 1S*, 14*

RS, 9 500k ± 5% 0 .1W trimmer

A7 10k ± 5%

A5 1.8M ± 5% 1/4W

A1 2, 15* 100k ± 20% pane l mounted pot

A16* see text

Sl SPOT 275-603

Ul C040 01 AE o r BE 276-2401

U2 C0400914049 AE or BE RSU

* Used only with the optio nal sidetone generator of Fig . ab

heat sink. For example, a TO-220package has a junction to ambientthermal resi stance R IA of 62 .5°C/Wand the junction temperature must notbe allowed to exceed l 50°C. Whenthe device dissipates 2 watts the junc­tion temperature rises 125°C aboveambient whic h limits the amb ient to25°C. The temperature near the tubesocket of a tube fina l can approach100°C. Under these conditions thepower dissipation in the switch wouldhave to be limited to 0,4 watts. A heatsink reduces the thermal resi stancefrom case to ambient and since thedevice 's junction to case thermal re­sistance, R

JC, is only few ohms (in

the range of 2°CIW), a moderate heatsink can be effective in reducing thejuncti on 's temperature rise .

In genera l, the die size of a devicedetermines the DC curren t rating andsaturated drain resistance, Ros ' otherconditions being equal. For example,Motorola 's MTP2N20 has an Ros of1.8 ohms, while the MTP5N20 has anRos of I ohm, and the MTP8N20 hasan Ros of 0.4 ohm. For a given drain

Tabh 2.

Fig. 4. A power MOSFET ran cathode -key ahigh power RF amplifier.

22 73 Amateur Radio Today -Januerv 1997

1.67°C/W a nd unde r the same co nd i­tio ns the d issipa tion is I \V and j unc­tion temperature if (30 + 1.67 )OC/W xI W = 3 1.67°C. Wi th a heat s ink. itcou ld ope rate in an a m h ient o f 118°C.

H o w e ver, if the cathode cu rre ntwere 2A. the power d issipated in the de­vices would he fo ur times gre ater a ndthe heat sink would he more im portant.Even w ith a 30 ohm heat sink the j unc­tion temperature of the MTP2N 20 is anunacceptable 234°C. The MTP5N20' sjunction tempera ture wou ld he 126.7°C.The lower Rps of the MTP8N20 resultsin a d issipation of 1.6W. Its j unc tiontemperatu re rise is (30 + 1.67)oC/W x1.6W = 50 .7° an d it can operate in anamhient of 99.3°C.

Clearly, the MTP8N20 is th e tra nsis­tor of c hoice if the cathode Current to heswitched is 2A whi le the MTP5 N20 canhe used to sw itc h 0 .9A in a I02°e amhi­e nt. A very thin coat of thermal grease be­tween tab an d heat sink IS needed toachieve the lowest the rmal resis tancefrom case to heat sink. Lo w thermal resis­tance is desired because lower Junc­tion temperature leads to longer life .

A li ll ie less than 8V of ga te drive isneeded 10 drive e ither the MTP5N20or M T P8N20 into d ra in sat urat ionwith 2A of drain c urr e nt. T he re fo re .the keyer power supply should begreater tha n 8 vo lts.

The power supply for the kcyer is no tcritical. except that the M O SFET Q Idictates a m inimu m voltage of 8 V orgreater and the C MOS devices lim it themaxim um voltage to l8V. The currentdrawn hy the kcycr without the sidctoncis less tha n 0 . 1mA an d a 9 volt trans is torba ttery has a life expecta ncy greaterthan WOO hours. The c urren t d ra wn bythe sidctonc generator is a func tion of

)'"

---is

KEYEDAMP

the audio power output. With l OOmWoutput into 8 ohms, the c urrent isI llmA whic h is best obtai ned w ith anAC powered s upply.

Adj usting or tuning the transm ittercan he done with a string of dots ordashes if the duty cycle is factored intothe me ter readings, 50% fo r dots a nd75 % for dashes. A "Tune" switch, SI inFig. 3a, allows the transmitter to he op,erated continuous ly for tunin g and thetransm itter 's meters to he read d irec tly.

Init i al adj ust me nt of the keye r to

produce the standard t imin g- do tand sp ace equal to o ne unit o f t ime .and das h equa l 10 three un its o ftime-is straigh t forward. T he o n lytes t equipmen t needed is a n aver­age -readi ng vo ltmeter, e ither an al ogo r d ig ita l. Be a w are that no t a llD VM s re ad average on t he DCranges. The p rocedure is as fo llo w s :

I . Connec t a n average - read ing DCvol tmete r be t we e n the drai n o f t heswitch tran si s to r. Q I , a nd grou nd.

2, Note the exact indicated voltagew hen th e "Tu nc" sw itch, S I , is in th e"X M IT' pos iti on . and the ke y is up .

The voltmeter will read +V o r E,.!u'3 . With S I i n "X:VU T:' close t he

ke y to the d a s h po si ti on a nd adjus tt he "space" tri m m er. R 9 . to m a ke

the mete r in d ic a te e xac tl y 25 % o fthe vo ltage meas ured in S tep 2. Th em e te r ' s nee d le w i ll n icke r if the"Speed" co ntrol is se t to o s low. Se tthe " Speed" con trol to get a steadymeter read ing .

4 . C lose the ke y to the dot posi­t io n a nd adj ust the "dot" t ri m m e r,R 3 , to m a ke th e me te r in d icate 50 %o f t he voltage m ea su red in Ste p 2 .

T h at' s a ll the re is to it. Th e"space" trim m e r contro ls the d ura­

tion of the space rela tive to the dashperiod. a nd t he "dot" t r immer con ­t ro l s the d urat ion of t he d o t re lat i veto t he d as h pe riod. T he dashperiod is con trolled by the "Speed"conrrol, R1 2 .

The sideto ne genera tor is a sep a­rate o p tio n that may be used o r not;it has no effec t on the k c yer. Itdoe sn ' t m on ito r tr a ns m itter o utp ut;it on ly m on itors w he n the key isdo wn and the transmitte r should bet ran smi ttin g. If your tra ns m itterdoesn ' t ha ve a buil t- i n sidctoncge ne ra tor, t his o ne ca n fi ll the g ap .

The ke ycr IS a fi ne we eke ndp roj ect for t he f1 a t- w a ll e tedbrasspound e r a nd the non-c rit icalcompone nts suit the m ost li m itedj un k box. W it h the de s ig n conside r­a t ions g iven, yo u can m od i fy thec i rcui t to f it th e parts at hand . Thekcyer ca n m ake g e n e ra ti ng the ki ndo f C W yo u l ike e asy , wi thou t spend ­ing a lot o f money- a nd it m ay helpc lean a few p ieces o ut of the

j unk box. Fa

NEU ER SRY DIEConttnuedJrom page 7

Mic higan Miracle is almost worth lookingat. The Michigan unemployment rate wasabove the nat ional average for 192 monthsin a row ( 1978-J993 ). It 's been below thenation al average for the last 28 months andMichigan has been turned from a rust belt toa growth belt state.

The Republicans have eliminated the $1.8billion debt: balanced the state budget forfive years in a row: cut taxes 21 umcst:downsized the state bureaucracy, while im­proving state services ; and eliminated abunch of red tape . For three years the statehas led the nation in wage increases. Jobcreation has heen at an all-time high. Mich i­gan has proven that tax cuts not only work ;they can work wonde rs! Now, i f wc couldjust get Clinton 10 try a tax cut. Instead heput through the largest tax hike in the his­tory of the country.

They've reformed welfare. with the resu ltthat over 90.000 Michigan families are nowon the payroll instead of the welfare roll.And one in three of the Aid to Families withDependent Chi ldren (AFDe) is working ascompared to one in 12 nationally.

Those Pesky ETs

There goes Wayne. off his rocker again.Wel l. some recent book s I' ve read have cer­tainly gotten me on a shuttle to wcirdsville.Unfortunately, since a good deal of it makessense, I' m going to share it with you.

Unless you've been squatti ng in a cavesomewhere, our of touch with the media,you know about Harvard professor JohnMack, who decided to loo k into the storiesof people claiming to have been contactedby aliens. His original intent was to showhow this contactcc stuff was all some sort ofmass hysteria baloney. li e ended up, afterfour years of resea rch. publi shing a book(Abduc l io ll) saying that the phenomenon isreal , which immediately made him a pariahwith his fellow professors.

If you've read Stueber's Communion, andhis BrcakthrOlIf?h , both of which are tediouslydragged out stories which can help you en­hance your speed-reading skill, you know thattens of thousands of people have been report­ing repeated contacts with ETs, and that mostof them don't want to talk about it.

A reader sent me a copy of Dr. Arthur

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Walking-Stick Beam?Hold il in """" h.nd--I, ·, . ",. '~;ng >lM'k ---11'--..-Ie "I' .'umi "un' "' ilh ' u""'" cr.k 1ltI. in·, ide.", , 1I 1he ol<mc" lSol'a 4 oIemonl ~.g' ' h•• -- f-­Ill"'" .n~l h.. in 2 minule<!. Re.dy 1". inc T·Hun ," lIcody In gel y..., ,,!\n_1 ou' or a I>nk,n'" II>.' "'pc_t",- ro;o huk fi,I' In dro!' .nd b":'k"" . E."'y'h; ng Ii" " k a" .nd "gh,.nd ""Sh.:!mo 'ors m. m em S4~. Wo ,~'" 0.01\ 1 lb. _Add Sot; Ship!,m~ & Handhng , loin I .A nlen nasWeM Older tlolLine

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73 Amateur Radio Today· Ja nua ry 1997 23

A while back an old man was struck bylightning-and survived. It was whathappened next that was so surprising. Hegrew a third set of teeth and a head of newdark bushy hair. His inoperable cancers

Continued on page 33

Rej uvenation

editorial, when von Daniken brought up thesubject of the Admiral Piri Riis map andcited a ham friend of mine, Father LinehanWI HWK, the head of the Weston Observa­tory, as an expert on the map, I visi ted himto see how well von Damken had done hishomework. I found that the map did indeedshow Antarctica as it was without the mileor two of ice on it. Further, as a result of themap, Fr. Linehan made soundings inGreenland, where the map showed it to betwo islands, and found the map was right.That was the first time this was known. Sowhere did a map showing an Antarctica andGreenland without ice come from? He saidit had been copied from other much, mucholder maps.

Oh yes, the map is cen tered from abo vethe pyramids of Egypt. Did you know thatthe position of Egypt's pyramids and theirsize is a replicat ion of the stars of Orion andthat the "ventilator shafts" in the Giza pyra­mid pointed toward Orion, Si rius, and theHyades when it was built?

Well, this stuff is more fun to read aboutthan endless stories o f the misdeeds andwaste of Congress.

Hom has done a monumental job of re­searching ancient writings and posi ts an an­swer for several major historical changeswhich have baffied arc heologists, such ashow man suddenly appeared, with no inter­mediary life forms having yet been found.And how, after a million years or so ashunter-gatherers, suddenly, in just a fewyears, man seems to ha ve domesticatedplants and animals, mak ing farming pos­sible. Then there was the sudden appearanceof towns and cities, which call for majordeve lopments in organization.

He also has done a remarkable job of re­searching the early days of the major reli­gions and explained many things aboutChrist and Christianity that I never heard inchurch. This is not stuff that any seriouslyreligious person should read. It's bet ter theydon' t kno w.

I liked the way Hom 's story tie s in withwhat I've read in several other books onEgypt, the Dogan tribe, Graham Hancock'sresearch, and so on. And Pat Flanagan 'swork too . He 's done a lot of pyramid re­search. There 's a new book our on Flanaganand his inventions by Nick Begich , the chapwho wro te the HAARP book, To ward a NewAlchemy.

Yes, all this flies in the face of whatwe've been taught in school and church, soperhaps we'll do better if we ignore trouble­makers like Horn and believe what we' vebeen taught and can sec . Any fool cansee that the sun is circling the earth, so nowonder Gali leo was given a hard time.

Hom's Humanity 's Extraterrestrial Origins,subtitled, "ET Influences on Human ity 'sBiological and Cultural Evolution." Yes,this sure sounds like another woowoo­weirdo book, based on wild speculation(imagination). Instead I found a very care­fully researched and thoroughly referencedbook. More about that coming.

Another similar book I read recently wasalso well researched and annotated. Thiswas Temple's The Sirius Mystery. I've writ­ten about that recently. But, as carefullydone as that was, I found Yin 's PleidianPerspectives on Human Evolution to be awaste of time. If you're interested in somesolid pyramid research you'll want to getthe $14 Bauval & Gilbert paperback, TheOrion Mystery .And also, Tompkins' The Se­crets of the Great Pyramid, which is $30and a big (416p) book. The mystery of howthese ancient civilizations suddenly sprungup is also d iscussed by Hancock in his Fin­gerprints of/he Gods. All these books tie to­gether in many ways, and lend support tothe conclusions in Hom's book that alienshave been around for thousands to hundredsof thousands of years and have been guidingour biological and social development fortheir own purposes.

Hom points out that the introduction ofmany languages and religions has served tokeep us at war with each other, thus keepingus busy and more easily controlled. Worse ,he goes into details on how the major reli­gions started, and then goes back to themost ancient of texts to support his theories.

Horn 's theories also help explain whypaleontologists have been unable to find anyDarwinian predicted chain of evidence forthe beginnings of man . Somehow, we magi­cally appeared, with no signs of intermedi­ate life forms having yet been found. Poof,suddenly there was man!

So, between Hom and his voluminousreferences, the Striebcr books, the contacteestories, the millions of UFO reports, andso on, these theories do help tie togethera bunch of evidence which mainstream sci­entists are doing their best to ignore ."Anomalies" is their explanation.

Being a pragmatis t, I tend to go with anytheory that helps explain the facts. I try notto get emotionally invol ved (make it a reli­gious matter), and am open to any other ex­planations which will also fit all of the facts(and not just ignore them). And Hom doesdo a good job of sorting out the facts andassembling them into a reasonable theory.

I have no problem with the concept ofaliens visit ing the earth hundreds of thou­sands of years ago and doing some biologi­cal engineering to provide them with a workforce. Or in some aliens still being aroundbehind the scenes, keeping track of andinfluencing events . Even if you accept thebig-bang theory (which I no longer do ),the unive rse is plenty old enough for ad­vanced civilizations to have checked out allhabitable planets millions of years ago.

Erich von Dliniken wrote about this stuffin the ' 60s and ' 70s (Chariots of the Gods ).As I mentioned a few yean; ago in an

Numoor 24 0 11 your Feedback card

Simple Mods for the RamseyFX Transceiver Kit

Customize it!

Peter A. Berg man N0 BLX3517 Estate Dr. SWBrainerd MN 56401

For those of yo u nor fami liar withthe FX series kits from Ramsey.they are 12-channeL diode-pro­

grammed. FM transceivers with an outputin the neighborhood of 5 watts. The seriesincludes rigs for 6 meters. 2 meters. 220and 440 MHz. The microphone, ease andspeaker are optional. The theo ry and as­sem bly manual is all I could hope for.That' s where the germ of some of thesemodification ideas came from.

Mods'? For a kit'! Wh y build in the lirstplace'? Scratch builders build fo r severalreasons. including the fact tha t the devicethey want may not be avail able at anyprice . It may be ami/able but not exactlythe way they want it. or they may want tocreate something which is uniquely theirs.I suspect that our primit ive ancestor whofi rst decided to keep the thigh bo ne s/hehad just used Cor bashing something mayhave decorated it for the same reason.

Front

Silk _---'Plate

Fig . J. Slide switches can be mounted easily{I/ points A, Band C. File notches ill thecase lOp 10 allow free 1II00"/:,lIwfll o] theswitch handle, The side plate may need 10 beshortened .1'I ightly.

24 73 Amateur Radio Today <January 1997

Kit building satisfies a large part of thatcreative urge. Modifying the kit is an evenlarger step in that direction. Besides, ifyou built it and it qu its working, you havea better chance than almost anyone tomake it right again, And it's just plain fun !

Onloff indicator

The fi rst change I decided to make tomy FX- 146 was to install an on/off indi ­cator. I could have wired an LED to the!XJwer switch or the wiper of the channelswitch but I decided to make it more use­ful by connecting it to pos ition # 1 on thechannel selec tor sw itch (S2). That'swhere I' ve programmed the repeater Imonitor 99% of the time. If I see a greenlight I know that the rig has power and itis tuned 10 the local repeater. I installed abi-color LED and connected the other halfto position # 12, where I' ve programmedthe CAP repeater. Now I have an LED in­dication that shows if I'm on channel I orchannel 12. I can count clicks in either di­rection and know what frequency I' mon-e-even in the dark, while driving.

A handi-ham suggested that it would benice if the rig hccped at channel one . Ihaven ' t done that to mine yet. hut itsounds like a good idea so I migh timplement that mod in the future.

Reverse polarity protection

The FX kit, as I received it, docs in­clude reverse po larity protection, An easyway to provide that protec tion in a kit orother proj ect is to install a nice heftypower diode backwards between the posi­tive line and ground. When power is

connected propcrly-c-ncgativc line toground- the diode will look like a veryhigh impedance- an "opcn't-c-and havelittle or no effect. But. if the leads are rc­versed at the power source the diode willlook like a short and blow the fu se beforeany damage is done 10 the rig .

In the December 1994 issue of 73,Frank Kamp K5DKZ describes anothermethod of reverse po larity protection us­ing a bridge rectifier. If you lise hismet hod it doesn' t matter how you app lypo wer as the bridge insures correctpolarity, Cheap insurance either way.

Non-standard splits

When I bought my FX kit ] was assuredthat it could be programmed for the CivilAir Patrol repeater frequency pai r. Sowhen I got to the programming phase ofconstruction I put in 146.52 like the boo ksaid. Then I installed the programming di­odes for the local ham repeater. So far sogood. Then I put in the CAP outpu t fre­quency o f 148.15. Fine. I could hear therepeater. Then I went 10 the auxiliary lineon {he matrix and tried to put in the 4 .25Ml lz split. After considerable study-andhair pu lling- I decided that I could getclose but not close enough. A couple ofphone call s to Ramsey later I' d learnedtwo things. The auxiliary line in the ma­trix was not se t up to be programmed for4,250 kHz or any other split that could notbe divided evenly by eight. And the bits Ineeded to program that split were therebut they were soldered to bo th sides of thepla ted-through board at U I0, one of the74HC283s.

A number of alternatives suggestedthemselves to me but I settled on thecheapest. I used a needle-point jeweler 'sfile to cut pins 6, 2 and 15 loose from theboard. They are, respectively. I. 2 and -tbib . Then each pin can be tied aboveground with a I<Xlk resistor and program­ming diodes run from each pin to the aux­iliary li ne a... need ed for your application.It 's kind of a combination of the worvt as­peers of "ugly construction" hut mine hasbeen that way for two years and stillworks line. If yuu arc absolutely certainthat you w'il l never ever want to install anon-standard split just solder U W to thehoard. If you think you mi ght, then socketthe dumcd thing so you can get to the pinslater.

Access tones

Most Civil Air Patrol repeaters shareone frequency pair and requi re aCTCSS tune for access. I had decided totry using another Ramsey kit. the TD- ITone Decoder-Encoder, to generate theaccess tone for our local CAP repeater.

The TD- I Tone Decoder-Encoder is afun link kit all by itself. The hoard isnot much bigger than an Elvis com­memorat ive stamp and only takes a fewminutes to assemble. hut it comes with a16-page manual that explains a lotabout c rcss and DTMF tones andgives so me ideas abou t everydayco ntrol applications.

All I had to do 10 get the TD-l towork for me in the FX transceiver wasto add a one-transi stor buffer stage andlevel pot to the hasic kit, as explained inthe TD- I manual. Connecting it to thetransceiver was a piece of cake sinceRamsey plainly marks the points for"PL" input and various points on thetransceiver hoard where I could get theg volts to run the tone board.

This gives me one tone which Ican turnon and (lIT with a little slide switch. Butwhat if I want more tunes'? The freq uency

of the TD- I is set with a precision pot.1I0w about installing a little sub-boardwith two or three pots and a fron t panelswitch to select the tones'? No. it won' tgive me access to all the CTeSS tones,hut I don't travel much anyway. Rumseydocs have a new kit, the QT- l SuhaudiblcTone Encoder/Decoder. I've not hall achance to try it out hut it is vel)' small anddocs generate any of the crcss tones viaswitch setti ngs.

You could also hook up a TD~ I as atone decoder. Then when it is turned on,your receiver would be silenced untilsomeone transmitted that tone. IImmm. Aprivate line. Wonder what we should call- -.,,-

If you are concerned about running outuf mom on the front panel look aroundand Sf..'C if you can lind a pair ofconcentricshaft pots-with an SPST switch. Thenyou could gang the onzotf volume andsquelch controls. That should help makemore room for your modifications.

Out-of-hand operat ion

All of the PX rigs arc capable of opera­tion outside of the ham hands. where youdo not want to transmit without the properlicense. A fl ashing LED installed in thefront panel--or wherever you want il­and wired to the appropriate channel­switch position will help you avoidcmbarrassing little incidents. And visitsfrom the I--"CC or X-Files. You could makeit beep there too.

Channel expansion

When I ordered my FX kit. one of myconcerns wa:.. that it has "only" 12 chan­nels, so once I had it working. I just hadto try expanding it. The method I waslooking for had to he chcup-c-excuscme-thrifty, and lit into the rig withminimum fuss and no external parts.I' ve seen plans for an int erface that al­lows the user to control the frequencywith an external computer and there is akit available now that moves program­ming to the front panel. hut I wantedthrifty my Im y.

The local cl ub operates a wee klyemergency services/rest net on the re­pealer output: if the machine quitswe"Il know where to meet and whatkind of coverage 10 expect . In fact.once. about 30 seconds into aSkywam Net the repeater too k a light­ning hit and went off the air. so I knewI wanted 147 .03 simplex. hut I did notwant to tic up one of my precious 12channels for it.

Once you have progra mmed a fre­quency you have to decide if it is goingto he +rpt , -rpt or simplex by installinga diode on the matrix at one of those po­sitions. I insta lled the diode on thewiper of a douhle throw switch and ranwires from the contacts of the switch to+rpt and simplex.

I knew before I started that I wanted 10

program 146.73 and 146.76. and when Ilooked in the book I saw that both frc­qucncics used the same number of diodeswith only one of them being in a differe ntposition. I decided that I could use thesame switching idea to put two repeaterpairs on one channel position. All very c14cmcruary to this poi nt. hut where do wepUI this growing numbc.... of switcheswithout creating a monster we can't usewit h out accidentally humping things'!Thesolution turned out to he so simple thatI' ve wondered if Ramsey planned it thatway.

If you look at Fig. I you' ll sec that theRamsey case is a six-piece clamshell de­sign. In each corner where the piecescome together there is morn, with a mini­mum of metalwork. to install a slideswitch. The switches. standard size ITlC­

dium duty DPDT. required a minimum oftrimming and filing to fit the case. Themounting cars on Ihe switches areclamped between the case bottom and in­nc-r plate and eithc-r the front or rear panelmounting cars. This mounting method isvery solid and has really stood the test ofli me here.

Ynu probably won't want to install anyaccessory switches in the right rear comernear the antenna connector. If you do youmight end up feeding RF to some part ofthe rig thai really isn't ready for it ami it'shard to predict what the presence of extra­ncous leads in and around the fi nal will doto your output.

Antenna connector

I' m one of those guys who reallydoesn't care to usc con nector adapters .Tbcy usually add a hit of attenuation andfrequently get lost. So install a B1'\C con­ncctor next to the stock S0239 and wirethem in parallel. There is plenty of roomand it shouldn't hun anything.

Conclusion

Naturally, before ),OU install tbesemods. or any others. it makes sense tomake sure the device works the way it'ssupposed to. If you have absolutely no ex­perience in building there arc a number ofinexpensi ve kits that will help you gelstar u..""I. Give it a try.

Both of the kits mentioned above areavailable fnun Ramsey Electronics, Inc.,793 Canni ng Pkwy, Victor NY 1456-1:phone (7 16) 924-4560. m73 Amateur Radio Today · January 1997 25

Num~ 2 6 Oil yout FNdlNJd ' urd

Build This Receiver Preamplifier... and lise almost anything for an antenna .

Stephen James Erst W9QHV17516 SE 96th Court

Summerfield FL 34491

••. '..

resi stors RF a nd RA. Because o f thehigh o pe n loop gai n o f the ampli fie rthe gain of the amplifier is RF/ RA. or20 d B maximu m . A Ik potentiometerchanges the effec tive va lue o f RA , rc­sulting in a minimum gain ofncar unity.

The amplifier is constructed using aRadio Shack" pcrfboard. and is rela­tive ly simple. Becau se- or the widcbandnature o f this amplifier care should becxcrci ..cd 10 prevent ground loops.which wil l cause oscilla tion. Thi sshould he checked using a detector onthe output with no sign al input. Thereshould not he any de- tector output withno input s ignal. A de tector configura­linn suitable for this purpose is shownin Fig. 2. Input terminals are providcdfur coax or a wire antenna and the out­put uses a BNe con nector to connec t 10the receiver.

The ampli fie r may usc almost anycomplimentary parr of tran sistors , Iused a 2N3904 for Q I and a 2N3Y06 forQ2. If wider bandwidth is desired. a2N9 18 and a 2N354 6 may he used . An­o ther co mbination is a 2N2222 and a2:\'2907. T he pinout for the transistorsused is shown in Fla. J .

.....

Photo It. The completed preamplifier unit.

T

~9V

:::;= .1 UF -=­C.'i

Outputto

Receiver

Q l 2NW04

Q2 2N3'J{ )(1

tSee text for olht:r Iypt:s .)

cellent sensitivity. Using a vertical 30·inch piece of number 12 wire. or a fewfeet of wire laying on the floor. signalswhich had been barely mo ving the S­meter were 101020 dB 0\'Cf S9 usingthe preamplifie r, even at 200 kHz.

Th is preamp lifier c an he easily co n­struc ted in a few hours. and this willbe ti me well spent. The design utilizestwo transi stors III a compli me ntaryco nfig uration with feedback to

broaden the freq uency response a ndpro vide the needed . lo w o utputimpedance ,

Ftg. 1 ill ustra tes the co nfiguration,T ransi stor Q l (N PN) III d irec tlyco up led to p~p trans istor Q2. Feed­hack from the co llec tor o f Q2 to theemitter o f Q I IS acco mplis hed by

Construction

('6 10 UF ...

. 1UFC4

uRO

0 5

n

!Oil

...--_ _-J'tJ!0'

OF

u0'

03

"0 '.'i ,ok

A~ t-<.....- ---l./ Q I Co'

CI .1 L> t:.e. '-----j f-.....'V"Vv-.. .1UF

What's happening on the 49meter hand'! Is 15 metersopen? How about IO'! Want

to look for beacons on 200 kHz'!If you are like most o f us. you don 't

have anten nas for every hand . If you arcan SWL you probabl y would like 10cover frequencies from 200 kll z to 30MHz or more. an d a hal f-wave antennaat 200 kHz is almost half a mile long .Don't despai r, there is a solution: a highinput impedance preamplifi er. T hepreamplifier must have a reasonablyhigh input impedance for random wires.either vertical or horizontal. and a lowoutput impedance 10 drive today's 50ohm input impedance rr..•c.civcrs. and itmust have an adjustable gain from I to20 dB.

Here is a preamplifi er thai le ts youusc a short antenna over the ran ge from100 kHz to well over 55 MHz. with ex-

L- " "'"_ ,----- .-.JFig . I . Preampli fier schematic ,

26 73 Amateur Radio Today • January 1997

I nlt lU\ll ltrminal

To pumplifier

Parts u e

S.6k..100

I k potor'lIiorne............ S\fIf*1l

0.1 j.lF rapae*w

10.0 j.lF eapedIOr

' ''''''''N39OO

9 volt battery

'NOIll: A Radio Shack Sk potennometer may be used.shunted by 1k In seeee with 2SO ohma.

RI, R2

R3. RS, R6. RF

RA

FW' (see 11018)

ct . C2. C3. C4. C5

C6

0 '02

Hook it up to a chunk of wire or what­ever you have for an antenna and checkit out. m

Fig.5.Presetectorfor the preamplifier ifspuriousresponse und imermodulation are problems .

Pans \'Olues \'Or)' depending on 1/w band.

=~ 1 "70 UF"V

O J IN400t

us VA I

Because of the broad bandwidth andthe high gain of this preamplifier some re­ceivers may be prone 10 intermodulationdistortion and poor spurious frequency re­jection due to signal overload. If you ex­pcricnce such problems. reduce theantenna size or preamplifier gain. If youstill experience problems. preamplifierpreselection may be necessary. To main­lain the high impedance of the preampli­fier a simple parallel-tuned network withcapacity coupling to the antenna may beused. One such network is shown inFig, S.

The performance of this preamplifie ris impressive because of its low outputimpedance and high input im pedance .T his project can be completed in a fewhours from the junk box or from partsreadily available from Rad io Shack .

Fig. 4. Suggested AC power supply.

1---r:...~;-----4>---'G~m1

RJ J9 M EG

Fig. 2. Detector f or ch ecking if thepreamplifier is osc illating,

1bc Ik gain control may use RadioShack's 5k potentiometer shunted by1,250 ohms made up from a lk resistor inseries with 250 ohms. An on/off switchshould be used to disconnect the battery.

The operating voltage may be pro­vided by a 9 volt batte ry or by an ACpower supply consisti ng o f a trans­former, rectifie r and filter capacitor.Regu lation is not necessary. A typicalpower supply is shown in Fig. 4.

E

B

C

Fig. 3. Pinout of the 2N3904 and 2N3906transistors.

1997 CharlotteHAMFEST AND COMPUTERFA IR

March 8 & 9, 1997 - Charlotte Merchandise Mart - Charlotte, NC

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Over 160 commerc ia l exh ibit boot hsAll major manufact urers will be here8 f t . swap t ables by pre-reg istrat ion only104 ,000 sq. ft . of indoor exhibit spacePark ing for 3,500 car sLargest indoor HAMFEST in the Southeast

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Ken BoydWA4 UNZ

(704) 377-8873

For m ore ticket information, write to:

Charlotte Hamfest and ComputerlairP. O. Box 221136

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73 Amateur Radio Today · January 1997 27

Number 28 Of! your Feedbar;1r urd

The bottom line.

RechargeableBatteries

The rechargeable battery businessis booming today. With the wide­ranging market in amateur rad io

and business-band portable transcei vers(HTs), the portable min iat ure ce llu larphone explosion. and now portablelaptop a nd note boo k co mputer sys­tems, rechargeable batt eries arc foundin many more areas of life than everbefore. Understanding some th ingabout the se batte ri es and their tec h­nology has also become increasi ng lyimportant, so here 's a br ief primer ineasy-to-understand terms.

1\11'. W iza rd s tun

All batteries work on a s imilar prin­ci ple : Current 110w between a ncgu­tivcl y-c burgcd meta llic plate and aposit ively-charged meta llic plate isstimulated by a highly ionized elec tro­lyte, suc h as an acid. Even a lemon.with its naturally acid ic juice. will ac t <Isa battery when two plates o f dissimilarmetallic composition arc placed wit hinit. Do you suppose that's where the term"j uice" comes from'?

Back in the old days

for decades, the only pract ical rc­chargeable baucry was the lead-acidhailer)'. primarily used in automobiles.boats and airplanes as a storage mediumfor electri cal power. The vehicle's en­gino. when running. can drive a genera­tor or ultcruator for recharging thelead-acid batte ry T hen. about 30 yearsago, nickel-cadmium rcchurgcublcscame o nto the sce ne and took up sonico f the market share for portable elec­tronic devices o f the time (larger "wet"

28 73 Amateur Radio tcasv » January 1997

Dave Miller NZ9E7462 l awle r AvenueNiles Il60714-31 08

NiCds were also used in stat ionary hat­te ry hack-up applicat ions, hut werecostly). Le ad-add batte ries soon chal­lenged Nif'ds" dominance in the por­table e lectronics field with a "gelledelectrolyte" version. Both battery tech­nologies have had their successes andd rawbacks in portable electronics sincethat lime. At present. we also have twonewer battery technologies strugglingfor our attention: nickcl-mctal-hvd ridc( N i~H ) and a rechargeable lithium for­mulation. Le t's take a brie f look at allfour competing formulations.

Borin g deflultlons

First. a couple of definit ions. A "cell"is the hasic unit. A number of cel ls arcconnected in se ries so that their cor n­

bi ncd contributions add together. So abattery' s ce ll is j ust one unit. and thebattery itsel f is u number of rhosc cellsconnected in series-add itive form. Eventho ugh we ordinarily call a flashlightcell a batte ry. that's not technically cor­rec t- you need IWO o r more cells inseries 10 make up a "battery" o f cells .

Lead-acid cells

Le t's look fi rst at the lead-acid ce llformulation. The biggest advantage oflead-acid cells is cost: they 're rela tivelyinexpensive to manufucturc . Lead-acidcells also can he easily kept up 10 snuffcharge-wise . wit h a co nstant vo ltagecharger, with no ill effects. In fact, theyra ther prefer that kind o f treatment. O nthe di sad vantage s ide of the coin. how­e ver. lead-acid ce lls arc heavy. Theyhave the poorest weight-to-energy ra tioo f all the batte ry fo rm ulations; lead is

heavy stuff! The acid used in lead-addcells <su lfuric add ) is noxious and corro­sive if spilled or if accidental leakage oc­curs. O ther forrnuhuions aren' t asimmediate ly destructive as sulfuric acid:it can be nasty! Eventuall y the lead platesin a lead-acid battery become clogged ornonporous (technically called "sulfated" )and the cell is no longer rechargeable.Lead-acid cells arc usually rated for 5(X)

{lr more recharges before thi s happens,hut it' s a lso predictable on a time-from­manufacture basis. The "spongy lead" inlead-ac id batteries ha... to be bee fed upwith the addition of antimony (a brittle.white-colored base metal ). An timony rc­acts with the acid and eventually cor numi­nates the "s[Xmgy lead." so lead-add cellshave a built-i ndock once the acid is intr o­duced. When thai cloc k runs out. the cellis unsalvagcublc. A Happy Motoring lip:Best no l (0 "push" your car baucry toomuch beyond its life-in-years rottingprinted on the casco

NiCd cells

Nickel..(..admium cells. on the other

hand. have a much better weight-to-en­e rgy outp ut rat io than do lead-acid cells.This can be very important to users oftoduy's miniature electronic devices,hut these batteries arc also mo re cxpcn­sivc to make. NiCds mai ntain a rela­tivel y constant ou tpu t vo ltage as they

di scharge, whereas lead-acid cells dropo ff (voltage-wise ) more linearly. ButNtCds also have a "memory effect" at­rributed to them. One man ife sta tion ofthis "memory effec t" is when NiCdcells arc kept on constant charge: T heytend not In deli ve r their full potentialcharge unless they' re first fu lly dis­charged. T he way this oddity in NiCdssho ws up goes something like thi s:When a NiCd cell is fully charged. itsopen terminal voltage is about IA volts .As the battery ' s reserve is drawn uponby the load, that fig ure drops fairlyq uic kly to 1.3 volts, then to 1.2 volts.The NiCd cell maintains that 1.2 vol tlevel right up 10 the end of its useful di s­charge curve, a t whic h po int it dropsquick ly down to 1.1 volts, and thenlo wer... all the way to zero . Wh en that1.1 vo lt po inl is reach ed the load sho uldhe removed. because furl her d isc hargecan harm the pack. In any pac k o f six,e ight o r 10 ce lls. one or two cells willa lways hit bouom firs t, and if the load is

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able cel l." NiMH cells can be chargedmore quickly than NiCds without loss ofpotential recharge cycles. They can standmore heat buildup, and, in fact, normallyget hottcr during recharge than their NiCdcountcrparts-c-but that's normal for theNiM H chemistry. They also don't ex ­hib it as much "memory effect" asNiCds do, but there is still somememory retention. The "normal" outputvoltage per cell is 1.2 volts, j us t like aNiCd cell. The number of charge/d is­charge cycles for the NiMH chemistryis about the same as for lead-acid andrapidly-charged NiCds; about 500.They're a bit more expensive to pro­duce than NiCds right now, but the pricewill no doubt drop as more companiesgear up for their production and theNiMH market-share increases.

Rechargeable lithium cells

The highest energy-to-weight powerdensity of all of the formulations is foundin the fourth and final formulation, the re­chargeable lithium cell . Lith iumrechargeables can pack double the energy(in terms of both volume and weight) ofNiCds. The specially formulated lithiu mcompound used in lithium rechargeablesproduces an open terminal voltage ofabout 3.5 volts per cell. Lithiumrechargeables are quite new, and thereforethe most expensive to produce. for themo ment. Man ufacturers are also hav­ing problems prod uci ng rechargeablelithiums in multi-cell packages, hut thatalso may be a temporary drawback.Lithiums are the most "environmentallyfriendly" of the lot and they have no"memory effect" at all. RechargeableIithiums seem to be the tec hno logy 10

watc h in the ne xt few years forrechargeable-battery-operated gear.

Non-rechargeable a lkaline cells

still connected to the pack, current inthe reverse direction will be forcedthrough the bottomed-out cells, causingthem to reverse polari ty. They're usu­ally not salvageable after that happens.Since the drop from 1. 1 volts per cell israpid, "smart" devices will automati­cally shut down at the point of 1.1 voltsper cell, saving the pack from poten tialharm. The memory quirk mentioned be­fore, however, causes the fast drop­down to occur at a somewhat higherterminal potential than 1.1 volts percell, so it can be a fooler. The pack (ba t­tery o f cells) becomes "trained" to ex­pect recharging at a higher point in itsdischarge curve, and therefore won'tdeliver as much energy to the load be­fore it "wants" recharging. It's shakenback into reality by o ne or two deep dis­charges, carefully monitored so that cellreversal doesn't accidentally occur. Soremember that NiCds can become" spoiled" by over-feeding, but it 's usu­ally a correctable mistake, even thoughit' s somewhat inconvenient.

It 's best to charge NiCds slowly, ove r16 to 18 ho urs, bu t rapid charging ispossible if the cells arc built to take theextra punishment. Heat is the enemy ofNiCds, and rapid charging causes heatbui ldup within the cell- it's a sign thatthe chemical react ion of recharging istaking place too q uickly for the cell tohandle properly. Rapid charging gene r­ally reduces the pack's use ful life by50% or so, about the same as that of alead-acid battery. It's often an acceptableprice for the convenience of rapidly re­chargi ng when that option is valuable tothe user. When the pack reaches fullcharge after being rapid charged, a slightdischarge can be detected and the rapid­charging turned down to a trickle charge(hopefully).

NiMH cells

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30 73 Amateur Radio Today· January 1997

A newer alternative to NiCd chemistryis NiMH, or nickel-metal-hydride. NiMHcells have about the same energy-to­weight ratio as do NiCds, hut NiMH cellshave a much greater energy-to-volume(physical size) ratio-about 25% more.ntis means that a NiMH cell can be thesame physical size (even though some­what heavier) as a NiCd, and will deliver25% more energy per charge. NiMH isalso more "environmentally friendly" andis sometimes cal led the "green recharge-

Just as a comparison: TIle non-re­chargeable alkaline cells that we're all fa­miliar with produce 1.5 volts per cell .Their energy-to-weight rat io is roughlydouble that of the heaviest of therecbargeables. the lead-acid cell, andabout the same as that of a NiCd. 1bcirenergy-to-volume ratio (energy to physi­cal size), however, is about the same aslead-acid chemistry, so they're muchworse in that respect than NiCds, NiMHsor lithiums (just an interesting aside). II

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The circuit

batteries, and can probably be constructedentirely from the contents of yourjunk box.

Because ITlOSt circuits requiring split posi­tive and negative voltages draw very littlecurrent, and usually do not require specificvoltage levels as long as the voltages sup­plied are within device specifications, simplerectifier/filter circuits providing unregulatedoutput voltages can normally be used satis­factorily. However, where specific voltagesare required, such as +12 and -5 volts, small100 rnA three-terminal regulators can easilybe added to the basic circui t.

The basic circuit for this dual, split-voltagepower supply is illustrated in Fig. 1. The ad­dition of regulators, if required, is illustratedin Fig. 2.

A small power transformer with a center­tapped secondary is required if two sets ofoutput voltages arc required. Ifonly a singlepair of positive and negative voltages areneeded, no center-tapped secondary isneeded. If you use a center-rapped trans­fonner, you can use either half, roth halves

TI 0 1

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•C3 W '" C4 J2 -9 VDC

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J5 -18 VDC

04

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J . Frank Brumbaugh KB4ZGCP.O. Box 30, cia Defendini

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11 7 VAC

A Positive andNegative Power

Supply

Many circuits using operationalamplifiers (op amps) requireroth positive and negative volt­

ages to operate correctly. This is quite com­mon, especially in many direct conversionreceivers, active audio filters, function gen­erator circuits, cte. Most cormnercial powersupplies produceonly positive voltages, usu­ally just+13.8 VOC, so you're going to needa simple rower supply to solve this problem.

Some hams solve it by connecting two 9volt batteries in series with the connectionbetween them becoming the common, usu­ally ground, terminal. While this does pro­duce ±9 volts, these batteries are not onlyexpensive, but have to be replaced periodi­cally. When something stops working righthow long will it take you to find it's apooped-out battery?

The simple power supply described hereproduces oot one, but two different positiveand negative voltages, and requires onlyeight inexpensive components in additionto the small power transfonncr. 'Ire totalcost should be no more that whal you wouldpay for one or two pairs of 9 volt alkaline

-F ig, 1. Unregulated power supply schematic . All capacitors are 1000 J1F'. 25 WVDC. Alldiodes are IN400J or equivalent ,

73 Amateur Radio Today· J an ua ry 1997 31

Fig , 2. Adding three-terminal regulators (0 ,!II' baste SIl l /ply circuit.

scpcnucly or the full seco ndary. dependingupon the reeds llf the circuits 10 be p owered

1llc basic circuit uses four half-wave di­ode rectifiers and fi u filter capacitors, andwill prOOlK.'C two sets of pos itive and ncga­live voltages. One. using the full sec ondary,is twice tha t of the other. which Us/"'S onlyhalf the secondary This p rovides consider­able leeway in selecting a suitable voltagepair. It also allow'S regulating either or bothvoltage pairs. using the small 7MLOxx and79LOxx regulators.

Terminal J3 i... conuroe to hl.1Ih voltagepairs. and uhboegh normally connected toground, it can he left floating if you want.However. it must be connec ted to the "co rn­

mon" in the circuit being powered.T he voltages given in F ig, I are

nominal voltages derived from using a12 VAC center-tapped secondary oftransformer T l. JI (positive, and J2(nega tive) provide ±9 VOC re ferenced

" It's almost impossible to wirethis circuit wrong-s-but

Mllrphy 's always lurkingnearby."

to B , common. Likewi se , J~ (positive)and J5 (negat ive) provide + 1S VDC ref­erenced to D .

These voltage arc nominal. wi th noload current being applied" and with 11 5VAC applied to the primary o fTI. Theremay he slight va ria tions fro m thesenominal val ues measured From yoursupply.

Construction

There is nothing critical in leadlengths nor component placement. Itcan he const ructed in any type enclo­sure, or even on a breadboard. butwatch out for the AC in put terminals.You can build it into the equipment inwhich it will he used. You may also

elimi nate T I by building it into your sta ­tion power supply, using irs powertransformer fur a source of low voltageAC to the rec tifier/filter circuits. How­

ever. if the ..tat ion power supply incor­porates a bridge rec tifier this may not hepossible bccuusc o f potential voltagedi ffere nces between power supplynegative. and com mon in this ci rcuit.

Be absolute ly ce rt a in yo u observethe polarities of d iodes and filter cu­pacitors. and double-check these be ­fore applyin g power to TI. A filte r

32 13 Amateur Radio Today· January 1997

From D I.C I JunctionJI 7MLXX/

From D2. C2 Junction, )2 7l.J LXX

13From rrnnsfonncr center lap

From D3. CJ Ju nctionJ4

7R LXX

1

From D..1. Col Junction ' J5 79 LXX

1

capaci tor connec ted backw ards candestroy ib a....ociated di od e. and canalso explode ! A n incorrectly installeddiode will apply reverse voltage to itsassociated niter capacitor. with similarfl rcworks .

Al so note the connec tion s to the78LOxx an d 79LO xx rcgulurors. whic ha rc diffe rent from each o ther. if theseare needed in your application.

Although not shown in Fl~. 2. you maywish to bypass inputs and outputs of eachregulator to enhance stability and to e limi­nate any hash impressed on the IX: volt­

age mils by the circ uits being powered.which could interfe re with proper regula­

tion. In this application. 0. 1 J..lF bypass ca­pacitors should be sufficient.

Remember to return B common. to

which the bypass capacitors are re­turned. to the com mon in the externa llypowered circui t. Us ually this w ill he theIX: ground, in which case the bypasscapacitors should be re turned to thenearby chass is ground. as wo uld 13.

A lthough the example illustrat ed inthis a rticle provides a nominal ±9 V DCand + 18 VDC. which should suffice fo rmost circuits requirin g a split voltagesupply. a cente r-tapped secondary of 24VAC will p roduce nominal ± 18 and ±36VDC.

Caution

A transformer supplying more than 12VAC will produce peak voltages exceed ­ing the diode peak inverse voltages andcapacitor worki ng voltage of th ose speci­lied. In this case. substitute componentswhich will withstand higher voltages.

/--------0 JI + LV Reg.

J2 · LV Reg.

n COITlI1l0Il

Jol + HV Reg.

J5 • IIV Reg.

Because c ircui ts requiring spli t vo lt­ages for proper operation draw onlya few mi lliamperes normally, a \'C'rysmall and inexpensive po wer tra ns­former can he u..cd for T I. A transformer

with a 12 VAC cente r-tapped secondaryrated a t IDO rnA or more should he suf­ficient. Just he s ure the secondary IS

cente r-tapped if yo u want two sets of

split voltages .Here is a rule of thumb which. if ap­

pl ied in every case. will save a lot ofproblem.. in the future : Every time asupply voltage e nters or ex its an enclo­sure. bypass inside (he enclosure , us inga 0.00 1 J..l F. 0.1 J..l F and 10 J..l F e lectro­lytic capaci tor in paralle l. T hese capac i­(Drs . acting in concert, w ill strip the DClines o f an y hash genera ted with in orextemul to each enclosure.

Operation

Check the voltages between D and alloutput te rminals before usi ng the supplyto power o ther circuits. A lthough it isa lmost impo ssi ble to make a wiri ng er­ror in a circuit this simple if care IS

taken to correctly orie nt the diodes andcapac itors wi th respect to their polari­ties" Murphy is a lways lurkin g nearby.So be surr before you apply power.

If the fo ur voltages and polari tiesmeasured arc not s imilar to these givenhere. turn it o ff and see what you'vedone wrong . Look for poor solder co n­nection s and reversed po larities . Re ­place any compo nents installed III

reverse with new ones. j ust to be sure

smce they may have been damaged .Feel the diodes. if they are warm look

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Cesspool

NCUCR SRV DICContinued from page 23

disappeared. He no longer needed hisglasses or cane and was completely healthyand looked years younger, much 10 the be­wilderment of the doctors who followed anddocumented his progress.

It may be that the doctors at the AlbertEin stein College of Medicine in New Yorkhave accidentally tapped into this fountainof youth in their AIDS research. They'vepatented the process, as have several otherhosp itals. but there's no word in the medica lliterature (or the press) of these hosp itals us­ing this blood purification system to cureAIDS . One might wonder why the silence.Well, that would be someone who has notdone his home work and read abou t a longstring o f other remarkable discoverieswhich have been given a similar treatmentby the medical industry.

Are the growing number of miracle curereports from people using the MillerBioelectri fier or the Beck "plant growthstimulator" true? Is th is simple. inexpen ­sive, and fairly fast process really curingvirtually every cancer case it 's bee n triedon? Is it curing AIDS? Lupus. Lyme Dis­ease. and a host o f other ill nesses? Is it re­ally causing people to lose weight and grownew hair? Is it giving them industrial ­strength immune systems which are able tofight off colds. flu, and anything else " goingaround?" That's what the medical reviewboard reports are showing. How soon willwe be able to see some research hospitalsfight off the pressures from the AMA andg ive th is approac h a rigorou s test onAlzheimer' s. cancer. osteoporosis, arthri tis,diabetes, and so on? Is the Department ofHealth totally anesthetized?

For that matter, considering the potential ,have you heard one single politician sayword one about this medical discovery?They don't dare without jeopardizing theirlobbying money from the AMA, the doctorsand nurse s organizations, the hospitals. drugmanufacturers , and the insurance industry.The higher our medical costs, the bigger theinsurance company buildings and hosp italswill grow.

Why am I not su rprised, considering thecorru ption in every ind ustry I' ve gotten toknow personally or read much about? Theamazing th ing would be if the $ 1.5 trillionmedical industry weren ' t corrupt.

Gee, I hate to bother you about this, butour 20m cesspool on 14 ,313 is alive andstinking. Yes, I wasted some time listeningto one o f our biggest public advert isementsfor the el imination o f our hobby. There wasone old man on there with a strong signal .prattling on endlessly about showing5addam Husse in a lesson. He was cursingfree ly and showed no indication thatthought had contributed anything to his opin­ions. Other strong voices were breaki ng

Continued on 55

Fig . J . Pinouts f or the common positive andnegative 10M! current regulators.

for possible shorts. The associated filtercapac itor might be leaky and need to bereplaced. Check also for any shorts tocommon .

I( you do not regulate the output volt­ages, you may notice that there is aslight difference between the voltagelevels in the pair being used. This isnormal and reflects the different currentrequiremen ts of the circuit bei ng pow­ered. If the circuit functions correctlydon 't worry about the voltage differen­tial, which is usually of no conse­quence. But if it really bothers yoursense of perfection, add regulators .

When adding regulators, remember thatthey require head space-highcr inputvoltages than the desired output voltages.The 9 VOC rails can be regulated to 6volts or less, and the 18 VOC rails can beregulated at 12 volts or less, and possiblyeven at 15 volts in most supplies.

You may be templed to use zener di ­odes as regulators. l don't recom­mended this because they will causeadd itional current drain, and the diodeand its dropping resistor have tobe matched to the current required bythe external circuit. This limits the uni­versal ity of uses for which this powersupply was designed. FIJ

Parts List

C1-4 1,000 ~F 25W VOC(minimum) electrolyt iccapacitor

01-4 Rect ifier diodes; 1N400 1or equivalent

J1·4 Terminals, your choice

78LXX 79 L.XX

. a ..«

T1 Transfonmer, 120 VACto 12 VAC center­tapped, lamA orgreater

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Columns

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..... Kaboom

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Deseription

Fl.""""Ca"'ty ~ Ito, lor ..t and 2mATiny2+ 1A roal ~.rtt ;n It>O ,""g"RF S".,,"'"

Indoor an'enna

A .YOl.y of amplifoe, co."

A ,eal fI'Im On tho ""'9"G,e.t projecr lor your c loo '22g-U•• " or 10'0 ilA groat clob p ' ojOC1Impro' e you r repeaM .y, lemBuild il lor I.., than $ 10'G,..., 0r><:l00f antenn. for OFlPIndoor ao,"onaA Slmpie stealth ant projoc'Th. ·oor""o,. ' antennaU~. 4 ~a~-..ave ~'POI• •F,actal co«nlo,poioa, or top hA'From you r t>.a...mo", lunk pile"'a ke you, an tonna"y high 'E..~y-<:on"rueted HF . y, tamV"" ean OX w,"'" . Ieolfll " "'Nea, Va,tio:allncide"". S~y,.,reN oar , o~ie;on', oa.y '0 bu, ldCoottollod CYrlon, Oi'I',Chaop and . implaE..y proj "'"Ao oldio bu t goodioATioy2+1A , mO" anlonnaTh o h ... to tho a"1<>oooLo..-.n ~fe " d,aoo"

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Record ox00 10 G HzTh o W,ndT,", prog'amH'1)h AM<>do Lih Off

u.... a TV eoio, bu,", "'Y...IMako rt ••00 mo,o u...IulStay legal0001 m... phone eall,

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Bui" 'h. B.,elecrn~",Budd Ihe aU AD-12 P...ona' DataloggorBuild Th is I3.m All", Ao"'nn.CW EnhaneorCi",u lato" , Aoyooe'Eoooorn"ol H' g" CYrT$"t P<>_ SupplyE.e,y Ham'o A"'gBIPeak Rea diogGarbage lo-No Ga rbage OutUn. VoHage Moo itofPVC Go.. CampingABCe,"~r AF P",. ,opRF Sn ,fl. ,Simple Inductanc. Me tmSimple Multi-u. o AmplifiOO $pea.OfTape-Wound AntennasTh e OiochargorThe JB Key.rTh. M.g"al .0.00'" F,'1<>r R."""t""Tha Sold.. SIUfll"'Th. Wnnd<>rtu l Twon·TT,an.min~rHunting EqyipmantUH FNH F Home-B'e.. M~aoYrio~ Gadget.

CW· COde

M and Ch allenge 01Sendio~ CWDo" and Oa. he.

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Gadgats

JoIInson ",atch"" , Ro nal••, ,,,,,,Mobit~ or Cha,,,ide HT Holde,Teiephon. Fla."~r

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11>0 Difterenc. , . Dedoc"ionW. a,na' CoonOi ."" ""nd CootrOiWhoelch air Mobil~

Worthy 01 Aecogn,'",n

H'.t"""

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A hard... ro .tora ca.,ty li llerOne-hO\l' ",,,,ee'F"il_~mo Rv.,. , lo ko n01<o'Imp,o•• p&rrormaoc. ot old r~,.

SimploEasy-ro-con. truel ,",numentSe/I -conta'oedNeot, e~",ren,- ...y 10bud~A NrCd " uroe to bY,klI.-o..·teen oo'uliO"An ea., w..,kend pr-oj"'"Bu ild 0 do.o"o' iog .,olionAu<!" Os,,, lIalor, no indLlOro..A club projOC1Aocy,ate, ea.y, • • ti....ing

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Ani ow"c hong for Q<Wer OFSnea ky d . vic.I.4ot"'ara. ..• nd m.'. it I,," 'A club P'OlOC1

DXing in sryloO~ to tha Gra.t Wni1<> No, th1996 Upds loJorda n;an ·I....li Op,

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34 73 Amateur Radio Today . January 1997

73 Review,

Numbe r 35 on your FefH1b llCk elln;J

HFx from Pacific Sierra ResearchCorporation

Nell' propagation forecasting software.

•

0_ '-"'-. . w_ o._,_--'-

it ' s true po wer can ' t be unleashed unt ilyou read the well -writte n manual.

Fig . lb. Spherical globalview of MaximumUsable Frequencies f or transmitter location,date lind time. This l'it'II' can be rotated (I IIeither axis.

­••••••non •

• •.........".'........"

you need is some good propagation soft­ware for that computer sitting on yourbench waiti ng to log a contact.

Pacific Sierra Researc h Corpora tion,o ut of Santa Monica. Cal ifornia . th inksth ey may have th e answer for you withth eir ne w propagation forecasting so ft ­ware, HFx. I know. you thi n k "propa­galio n software" and your mi ndp ictu re s arca ne DOS program s thatgovernments use to find o ut just whe nto Flood an uns uspect ing co untry wi thshortwave broadcasts o r get th at super­secre t message through . There arc anumber o f the se programs Fl out ingaro und an d th e key phra se for them isnot intuit ive . Well . HFx is a Windows­based application that is desig nedaround the concept of po int -and -clic k ,Out o f the bo x I fou nd myself bei ngab le to play aro und wi th HFx, tho ugh

Richard Lubash N1VXWrlubash@poco.mv.com

A s I start writing this review it hasbeen 36 days without a single spot

being sighted on the face of the sun. Thelast lime o ld Sol had such a long periodwithout blcmi..hcs wa... 19""', two yearsbefore I was rom. We arc indeed in themidst of the solar doldrums. At a timelike this. a litt le magic or it crystal hallsure would come in handy-c-just that ex ­Ira edge so you could find thai lone OXstation up on 20 meters that hasn'tshown up on the d uster. With so manyhands and so little time. it sure would henice to kno w where 10 look . Or maybeyou have a huddy in Shiproc k. NewMexico, and wo uld li ke to set up a skcdon 17 meters bUI due 10 low nux levelshaven' t t een very success ful. w ell, what

Global MUF - Re cl anl)Ula! PIOlllC tion 1iI.13What is HFx?

HH. HFx is a powerful HF pro pagationtoo l that calc ula tes ionosphericskywave signal stre ng th from 2 to 30MHl . HFx uses a ve ry intuiti vegraphica l user inter face that heavilysupport s po int -and-d ick a nd bases itsopera tion o n virtual -raytracc algo­rith ms dev eloped by ITS and CCIRover the last 30 years. The so ftwa recreates th ree d istinct o utput model sdes igned around user input o f:

The geographic posi tion of bothtran sm itter and receiver

Emission power and antennacharacteristics

Date and timePropagatio n path (long or

shan)Solar fl ux or sunspot number

and K index73 Amateur Radio roosv » January 1997 35

30'

'"'16U

'"22.07lJll

'"'16.0

'"12.0lO ,1Jan6.'

'"2.'

Highest Po-nible F,~

~~

Fig. t o . \Hlrld dell' showing Min imum Usable Frequencies for transmitter location, dareand time,

...._.,.,--o _ .... ,-

" ....

••••"•• 0 .'¥.. ...._.

,•

'- -·,. ...• •

'- I

•,,• •,••,

•

HFx system req uirement s arc a liulcmore robust than the typical ham festj unker PC. but with many hamsupgrad ing their sys te ms running itsho uld not prove too great a challe nge .Minimum co nfig uratio n is:

a plot of a vailabili ty and signal-to­noi se rat io for the HF am ateu r bands80-10 meters d uring a 24-hour period.(Sec Ffgs. 3, 4 and 5.)

•' ~.---s---~--~--!

- ,"_ 10 1

-,",,m•,•,•• •,

•

I ~

..•

I i I

••.... .• •••• ••

~ . \~~-""::' -,

.'.

••

,•• •

hours yo u can enter data and get re ­sul rs in a matter of seco nds. and it he­comes fun to see what the softwaresays about the possibili ties for theQSO you arc curre nt ly hav ing . I de­cided to give HFx a shakedo wn bycomparing it s pred ictions with the ac­tual co ntacts being made d uri ng the' 96 CQWW RTTY and CQWW SSBco ntests. I decided to not o nly test itagain st stations that I heard from myQT H but al so agai nst s tatio n s ig hti ngsthat ca me in on the DX cl us ter duringthe co ntest. I was ab le to se t up thetra nsmit locat ions on c lus ter spots us­ing the lat itude and longitude informa­tion fro m a cal lsign CD ROM. a ndused the scrclluble list o f call sig n pre­fi xes on HFx for the DX statio n 100;U­tion . In addi tion . I used HFx In set upa number o f skeds with statinns herein the US based o n op tim al timespredicted by the software .

Fig. 5. Signal-to-noise ratio for mmsminerlind receiver on -If) meters over (J 2.J-hullrperiod,

FiR. 4. Hop mode availabilitvfor transmitterand receiver on -10 meters over a l.J-hourperiod .

Operation

386-ba-,ed PCWi ndo ws 3 .1 or higher. including

Windows 95Hard drive with 6 megabytes o f free

space3.5" floppy drive4 megabytes of free RAMMouseSVGA monitor set to 256 colors at

6-U) x 480

The mai n operationa l window co n­sis ts o f a world map and two too l barswhic h pro vide access to all of the fea­tu res incorpo rated in HFx (sec Ftg , 6 ) ,

The map can be configured to showtransmitt ing and receiving statio nplacement, so lar position. major worldcities. great ci rcle path between Txand Rx. aurora l bo undari es based o ngeomagnet ic activi ty and day/n ig httermi nator. The window can be resizedvia the mouse and the world view willauto matica lly resize to the new win­do w posit ion with no need for scroll­ing . The syste m comes wi th anexte nsive online hel p system thatmimic s the we ll-writte n and illustratedmanua l. Polit ical and state bo undariesare not shown on the world map butdi alog bo xes allow entry via ascrollab le list of ca ll p re fixes so Ihatp lacing the transmitter and receivercan be accomplished without the aid ofa world atlas.

Afte r playing with HFx for a few

"HFx is a powerfill HFpropagation tool that

calculates ionosphericskywave signal strength

from 2 to 30 MHz."

~-

- "...• •••" • ."..

• .., ..• .., "• .., .., •- - • ..

. " ". • .... ..1"' 1 :::;,,] --.:J

-Tcmporal MUE which co nsists of a24- hour graph plot ted for a path be­twe en the transmi tt ing statio n an d re­cciving station with freq uency versusUTe time for Hi ghest Possible Fre­quency, Maxi mu m Usable Frequencyor Optim um Traffi c Freq ue ncy. (SecFi~. 2.)

FiR. 3. Hop path for transmitter and receiveron -10 meters til 1200 UTC

36 73 Amateur Radio Today · January 1997

-Hop Mode. whic h provides both agraph ic re presentation of the hop pathbetwee n trunsmi ucr and rece ive r. ami

-Globul MUF, whic h is d isplayedby use r choice on a fl at or sphericalworld map that can be config ured forHighest Possible Frequency, Maxim umUsable Frequency O ( Opti mum TrameFrequency. (Sec I'i~s. 111 and l h.)

After you inpu t the above informa­tion via dialog boxes or I:ly point andd id on a world map. Hf- x wi ll gi ve) 'OU the following mod els:

Fig . 2 . lI;gh"~ 1 Possible Frequency, Maxi­m"III Usable Frequency and Opt imum Truf ­fie Frequency ptoned belli"""" mmsminerand receiver f or a 2.J-hIJllr period,

Fig. 6. Main screen. showing transmitting and receiving station placement. solar position. majorworld cities, g IYaJ circle path between Tx and Rx. auroral boundaries based on geomagneticacti"ity and day/mghr terminator. These items may be turned on or offat user i" discretion,

,.

CIRCLE 10 7 ON RUOER SERVICE CARO

",

Availability

HFx is pr iced at $ 129. If yo u arc onthe Internet you can get product infor­mation, order HFx or dow nload ademo copy of HFx at: <htt p://www.psrv.eomlhfxl>. Or, contact thecompany di rectly : Pacific Sierra Re­search Corporation , 290 I 281h s t.,Santa Monica CA 90405·2938; (800)820-4PSR, (3 10) 314-2300 outsideUS and Canada . II

CIRCLE 54 ON READER SERVICE CARD

73Amateur Radio Today · January 1997 37

should understand that any propaga­tion program j ust coliales past statlsti ­cal data in the hope of applying it tothe future, which is never entirely pre­dictable. Using propagation softwaredoes, however, give one a place 10 startwhen turning on the rig and wonderingwhere that OX might be lurking orwhen the best time is to call that friendon the other side of the country. Thelill ie bit o f magic that a program likeHFx can perform sure can't hurt, and,after all , doesn' t amateur rad io involvej ust a lillie bit of magic?

TIle POWER POCKET is aYailJb~ from mos/major Amateur Radio Deaiers, orcomect

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12Vtl .OAmp Hours 01dependablepower. inaconvenient soft case.Simply insert the cigarette adapterplug normaly used in your car's~ghter 10 instead plug into thePOWER PlXKfT.The POWER

PlXKET provil:les hours 01 eXlended talktime. up to 6timesIoogef than standard battery pad(s!

• Emergencies - Special Events - Search & Rescue - Hiki "'ll­Cycli"'ll- Hamlests -FIeld Day - Etc.

•Compact slim design Ihat is light weight.only 30 ozs., WIth abell loop and shoulderstrap included.

. 11rN Walt Charger ind uded. Charge rate:6·8 hours fromcompklte discharge.

• Sealed leadacidcase, can be recharged to100% without memory effect of NiCads.

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but for now I think the folks at Pa­cific Sierra Research Corporationhave a wi nner.

Although it wou ld take a seriousamount of research with both transmitand receive stations available at di ffer­ent times, places, times of the year,and so lar conditions to thoroughl y testout any propagation software, J foundthe resu lts that HFx produced for bothmy contesting experiment and settingup skeds to be quite impressive . One

Conclusions

The results of my unofficial fieldtesting were quite amazing . HFx wasable to predict that communicationshould have been possible for recordedDX spots the vast majority of the time.In many cases, HFx showed a smallwindow of opportunity at the Maxi­mum Usable Frequency and, sure

"1 do like technology and, likemost hams, I love toys; HFx

fits both requirements."

enough, spots would start showing upon tbe cl uster. I also checked HFxagainst my station log randomly over aperiod o f about six months and thevast majority of contac ts fell withinthe ploued window of opportunity. Ifound the hop mode to be quite educa­tional in that it gave a graphic repre­sentation of the sig nal path,availability and signal-to-noise ratio.

I enjoyed using HFx . J don ' t have a"big gun" station and probabl y neverwill. but I do like technology and, likemost hams, I love toys. HPx fits bothrequirements. I would like to see thenext release of the software include adisplay of Lowest Possible Frequency

.and possibly dy na mic real-time e ntryof the time at the transmi t location,

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38 73 Amateur Radio Today · January 1997

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1·8QO.-81().4PSR~AX, 31().31 4·2323O utside the U.S. & C. nada:3 10_3 14· 2300[ · mail: hfx%mgat~p.rv.eom

\~... and Ma>tciCard :lCQptM$129.00 postpa,d wotldwi<lc

For more information or ' 0order. u ti or wrile u.s at:

CIRClE Z26 ON RUDER S ERVICE CARD

73 Amateur Radio Today ' January 1997 39

This is a cool producn _ Hdm Riu/io Onlint'

HFx will become a powerful foece in the field of HF. prop;tplionpredicnon and anal~is. - QST

HFx figum among the mOSI complete and 001developedprediction software tools. - ldrgdhrrtz

V~ry intuitive and visual . . . easy ( 0 underseand! - CQ (jdpd n)

lr's uncanny how accurate (l Ih) is! - N9VHW

Check OUI o u r W(Cb site for moreinformation. Take rhe guidedlOur or download a demo copyand ny it OUI yourxlP.

Imp://www.psrv.comll#

Here'$ what people are wying obout the beit propogotion Mlftwore ovoiloble:

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73 Review

MultiFAX® AM/FMWEFAX Demodulator

Fine-tuning a satellite Tracking system,

Plw lf, ,t. MFMAP7 provides II rent-time XHlf/hicul (li.WIIl)" as it plots satellite tocatians ,

40 73 Amateur Radio Today <January 199 7

Larry R, Antonuk WB9RRTP.O. Box 452Marlborough NH 03455

I had spent the last several weekendsworking on my overall weather satellite

Automatic Picture Transmission (APT) rc­ceiving system. My Hanuronics R1.19 wu'..

huilt and working well . The woodbou-cCommunications Turnstile antenna wasassembled and mounted on a tripod on theroof. along with my L"G·137 preamp. Iwas receiving weather satellite transmis­sions left and right. Unfortunately. most ofthe passes I received were coming in to­

tally randomly, I wass simply recording ev­erything that came in. and laboriouslysorting through the pile later. This worked.hut it took several minutes to watch eachimage paint itself on the screen-s-only tolind OUI. in some cases. rhat it W'LS a totally

uninteresting shot o f some douds out overthe ocean. Since I was primarily interestedin the weather occurring in my own gen­eral vicinity I found that I was wasting anawful lot of ti me. It ....u s time to do somehomework on my new demodulator.

J purchased my demodulator based onrecommendations from a couple of knowl­edgcabic friends. ruther than o n my ownunderstanding. Once I had my weather re­ccivcr up and running well enough to hearanyt hing. I fired up the demodulator andlearned enough about it to demodulate pic­lures. Tbcn I went hack (0 improving myantenna installation. Now thai the antennawas installed I had time to fine-tunc thefi nal part of the system.

My demod ulator was the externaldemodulator unit from Multif-AX$. Thisdemodulator works in conjunction withMultiFAX's l\.1FMAP Version 7 soft ware,providing a means 10 decode several types

of weat her satellite images. I was new tothe satellite image business. and wasn'tsure exactly what I might he wanting 10

dec ode-s-either right now, or in a year ortwo. The Mult iFAX unit supportedNOAA, Meteor, GOES. Mctcors.u and HfWEFAX. I had abo chosen the Multi fAXbecause it comes in an external vcrsion-c-Ididn' t have 10 tear my PC apart 10 install acard. and I could easily usc the externalunit with my laptop . (Of course. the~1ultiFAX docs come in a PC card modelfor the dicbards. ) The MultiFAX hookedup via the PC's printer port for fu ll paralleldata ofll..muion. I knew that some units onlyused the serial port. which limited theiroverall data throughput. (l had certainlylearned this with my experiences withthe home-brew, shareware-supported de­mod ulators.) Another necessity was theabilit y to record satellites unaucndcdc-Icertainly couldn' t he home to li re the soft­ware up in the middle of the day.

What li llie knowledge I accumulatedhad easily taken me to the point where Icould decode and display images. The in­srallation of the unit itself and theMf~IAP7 software wax a cinch-cjustplug the box into your computer with tbesupplied cable. copy the files from thedi..k. and hit the road. ~1FMAP7 takes upabout 8(XJ kilobytes on your hard drive,hut you'H need about 4 MB total availablespace. A complete satellite pass gets "re­corded" to the hard drive in real ti tre. andtakes as much us 3.5 M per image! Aboutthe time I decided I needed to learn moreaboutthe MultiFAX uni t I ulso found out Ineeded to do something about the coupleof dozen 3.5 MB files on my hard disk­things were getti ng prcuy crowded!

Using if ! Sim ple!

At this point I decided 10 read tbcmanual. which. in retrospect. was not a

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Once you have the proper images re­corded. the ~1ultiFAX software supportsgrid and map (unctions that allow the userto overlay latitude and longitude lines, aswell as map information. More advanced"frosting on the cake" features include theability to create pseudo three-dimensionalimages. colorization based on tempera­tures. infra-red optimization to allow tern­perature data to be read directly from animage. and even animation. (Yes. you canproduce your own moving cloud imagesjust like on the six-o'clock news!)

The Multi"'''AX WEI-'AX Demodulator;combined with the Hamtronics R139 re­ceiver, and the Woodhouse Turnstile an­tenna, has proved to be a very satisfactoryweather monitoring station. However,even with all the resources available, in­cluding one's own "eye-in-the-sky,"] stillfi nd myself occasionally getting out­smarted by the weather. I suppose this issimply Nature proving that she's superior to

technology, and may never change. Until itdoes, I still keep an umbrella in the trunk. Fa­nnedctailscontaet:MultiFAX-,321 MasonRoad, Fairport NY 14450; Telephone (716)425-8759; FAX (716) 223-6 198; BBS (716)425-8759. I!l

corrected once in the Display menu.) Asthe unit records, the image is traced out tothe screen a line at a time, over the nextseveral minutes. A keystroke stops the re­cording, saving as much of the image ashas been recorded up to that point.

The recorded image is then called backup in the Display menu. This menu allowszooming in and out, inversion of the im­age. changing of the brightness and con­trast. false colorization, and a variety ofother functions. A section of a Picture issaved as a View, which takes up only a fewhundred kilobytes of disk space.

Scheduling the recording

After the novelty of satellite imagingwears off, you 'll find yourself not neces­sarily wanting to record every singlebird that passes within earshot. You' llprobably want to tailor your recordingsto capture just passes that go right overyour location, or perhaps you want tocapture all the images you can-but justin the three hours before Saturday's ballgame. In this case, the Record menuoffers a timed fu nction that will start re­cording a single image at a specific time,based on your computer's clock. In addi­tion to this "wait until recording" mode, f----- ---- - -----­MFMAP7 also includes a utility that al­lows use of a separate schedule file. andwill call the Record module at specifictimes. Using the feature you can recordup to 200 passes automatically-as longas you have about 700 MB of spaceavailable on your hard drive!

But how do you know when the satel­lites will be coming over so you can setthe timer properly? Luckily, MFMAP7has a built-in satellite tracki ng funct ion.This uses a graphical display that showsa world map, and traces the path andfootprint of each of the satellites. Thisdisplay works in both real and acceler­ated time, so it is very easy to see whatwill be visible from your locat ion for therest of the day. The software even tells youthe number of hours to wait until the nextpass of the selected satell ite. Of course, aswith all tracking programs, you'll need todownload the Keplcrian elements on aregular basis so the program can fine-tuneitself. These arc available from theMuitiFAX BSS or via the Internet. Thesatellite tracking feature of MFMAP7 sup­ports the Kansas City Trucker system.meaning you can have the software auto­matically adjust your antennas for you asthe satellite passes over.

bad move and perhaps should have beenettemptcd earlier on in the game. To beginwith, I found that there was no reason tosave all of those fat files on my hard drive.The MultiFAX software uses three maintypes of files. The fi rst type is a Picturefile. This file is a complete data recordingof the entire satellite pass. and is the 3.5MB file discussed earlier. This file is re­corded from lhe pass, or the tape recordingof the pass, and stored to disk. Oncestored, the image is called up using theDisplay menu of the program. The displaymenu lets you zoom in and out, invert theimage, change the brightness and contrast.and perform various types of image en­hancement. Once tbe image is modified to

provide the best picture, you can save it asa View fi le. A View file is saved in binaryformat, and consists only of the interestinginformation cropped from a Pict ure file.This lets you save just the valuable infor­mation from each image, and not use updisk space with useless images. Tbc thirdfile format is the common .GIF format. Ei­ther the View or Picture screen lets yououtput the image to a .GIF file that can beeasily used in desktop publishing pro­grams or pri nted out.

Once I determined that there was noneed to be hoarding those huge Picturefiles, the process became much simpler. Torecord a file, you simply select the Recordoption from the Main Menu. This lets yougive a fi lename to the image you arc aboutto record. At this point MFMAP7 displaysa graphic signal level meter. This wouldmore accurately be called an on-screen os­cilloscope. The meter is a display thatshows the relative "brightncss'tlevel of thereceived signal for its entire trace acrossthe screen. A too dark signal will be seenas compressed ncar the bottom of the dis­play, while an overly white image will besecn crowded ncar the top of the display.It 's a simple matter to adjust the outputcontrol of the MultiFAX unit to correct theimage, providing a proper range of con­trast for the image-bcfore you even startrecording. Once thc contrast is adjustedyou simply hit any key, and the MultiFAXgoes into AutoStart mode. This mode syn­chronizes on the left edge of the image, sothe recording will start at the proper timeto create the image properly aligned withthe screen. (Of course. if for some reasonthe signal is lost and the image starts re­cording with the edge going down themiddle of screen. the situation is easily

73 Amateur Radio Today - January 1997 41

Numbe. 42 on you' F.-d~c. ClJrd

An Enhanced Automatic VoltageController

Make this project el'ell l/lOre usefu l ,Sam Ulbing N4UAU

5200 NW 43rd s t.Suite 102-177

Gainesville FL 32606E-mail: n4uau @afn.org

Itry to read all the projects pub­

lisbcd in the amateur ndio litera­lure, especially ibose in 7.1 and QST.

Tbcre are many neal. ideas in these unklcsand sorrcurrcs if I find a (XOj..~.:1 I can use inmy shack. I' ll w ild it. Even if I don' t wild

the project, it is fun In see the different solu­tions people otTer to solve a problem. I havelearned a lot about elccuon ics just trying tounderstand 00w the different designs work.

and I like 10 design prujl.'\.1.' myself. SO I amalways looking al a project 10 see if I can

think of a different (and possibly better)way,

I rece ntly read "Automatic Volw!:!c Con­troller' (73, August 1996). It seemed like agreat rrojL'Ct and was one I wan u..xl to build. Ihave had firsthand experience with voltage

F It:_I . Schematic f or the modified Tinv Tic- Tile Tester (left ) with the enhanced vohage controller triglnJ.

42 73 Amateur Radio Today · January 1997

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out-of-range problem". I use an IC-735 onmy sailboat when I cruise, and like all sailors,I never seem to keep my batteries fullycharged. One day when transmitting, the rigjust shut itself down. Eventually I got it re­started but it was not the same. Evidently thelow voltage had ruined one of the ICs in it.That turned out to be a $100 learning experi­ence. Is it any wonder I was interested in thisproject?

Enhancements to !heAVC

After thinking about the project for a fewdays, I decided 1 wanted to enhance it. Theproject shown uses zener diodes to set the up­per and lower voltage control levels, whichworks fine but doesn't let you see what theactual voltage is during operation. You mayrecall I wrote a project article for 73 in March1996 ('7he 'TIny lie-Tac Tesr.er") that wasbased on an LM3914, which accurately dis­plays voltages. I wanted to add this featureand use it to control the relaysas well.

Another feature I thought might be usefulwas latching relays. Low voltage often occurswhen you are transmitting. When you stoptransmitting, the load decreases and the volt­age increases. With the original design, theAVe would tum on again; indeed, it seemspossible that the relays would charter on andoff. I wanted to have those relays trip and staytripped until I was able to correct the problem

Finally, I wanted to eliminate as manyof those mechanical relays as possible andusc electronic relays. My enhancementeliminates two of the three relays.

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73 Amateur Radio Today· January 1997 43

Fig. J shows my enhanced controller sche­matic. I have drawn it in two parts. The left­hand side is the same circuit used in "Ihe'TIny Tic-Tao Tester," with RI, R2 and R3 setfor a voltage range of 11.4 to 15.0 volts. A

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Whi le the circuit docs not draw muchpower, it is possible to reduce the current toaround 12 rnA by oper ating the LM39 t4 inthe dot mode. This will also reduce the powerdissipated in the Uv13914. lf you wish to runthe LM3914 in the dot mode. LED #1 'Willnot work as a control point because it has toohigh a leakage current in the dot mode (thisis a basic LM3914 design fact). The circuit iseasily modified, ax shown in Fig, 2. R 15 willcause Tl to be on whenever (lily LED is on.When the voltage falls below 11.4 vOIL<; all

the LEOs turn off and no current flowsthroughRI5 (except leakage current).SettingR3 a1 ahout 360 o hms (for 4.0 mA of LEDcurrent) gives a voltage dropofabout 1.4 voltacross R14 when any LED is on which turnsonTI.

•YOL'l'AGE

FAULT

tgl

V01.TNJE <X»rrRo~

FOR 6 et:w,lZAD ACIO llll.1'TBlUES

I 1 I 11" 1~.' '~. I 1• .•

- =-"

12 vee CONTROLlJ!:R

Photo C. "GIII.I' " of the Enhanced Automatic~hlta~e Controller. Note the simple paristavont on the Radio SIwek PC board,

Alternative circuits: Using the dot modefor voltage display

Photo B . Enhanced Automatic Vo{WXeController ill its "eiegant" case ,

ffcrs a feature no digital meter can. It can beill active part of the circuit, allowing it to con­uul thc circuit as well as displaying the volL­ge in a passive fashion. To see how this

works, note that I have attached a wire fromthe cathode of LED # 10 (the one that turnsonwhen the voltage reaches 15.0 volts) to the

asc of transistor 1'2. When the supply volt­gc reaches 15.0 volts.the LM3914 turns on.EO# I0 by allowing current to now fromits

athodc to ground. When it is all", theLM3914 does not let current now. Because1'2 is connected to the cathode of LED #10,

urrcnt will also now from us base to ground

so 1'2 turns on when the LED turns on. Sowithjust one additional wire the L\139 14 cantum on a control transistor when the voltagereaches 15.0 volts.

'The other control point is when the voltagefalls below 11.4 volts and LED #1 turns ofT.This is done the same way except that Ivanted 10 tum on 12 when LED # I turnsOFF rather than when it turns ON. T I is usedo invert the effect of Llils s l. When LED#\s on, current is flowing from its cathode to

ground, and because Tl is connected to itscathod e, TI is also turned on. This puts V+across RI3, and therefore on the base of 1'2,preventing current now from the base of 1'2.\\!hen LED # I shuts ofT, T1 shuts olT and thevoltage across R13 goes to zero, which letscurrent now from the base of 1'2 to ground.turning it on.

'The diodes D1and D2 prevent interactionbetween LED # I and LED #10 and makecontrol of1'2 an "OR" operation. If LED #1IS off or ifLED#IO is on,TItums on.

With the LM3914 voltmeter now turningon 1'2 at the limits I set, I needed 1'2 to trip alatching relay. Q I is that relay. Q I is an sili­con-controlled rectifier (SCR). One charac­teristic of an SCR is that when it is turned on(conducting) it will continue 10 conduct untilthe current through it stops. In other words, itis latched on. The gate of Q I is used to tum

the SCR on. When 1'2 is off no current flowsthrough R9 so QI 's gate is at ground and Q Idocs notconduct. When 1'2 turns on, the gateis pulled high and current flows through Q I ,energizing relay K 1and opening it. Tbc onlyway to close the relay is to stop the currentthrough Q I. Push-button PH I docs this resetjob. LED #11 indicates that the circuit hastripped.

That's all there is to it! The circuit drawsabout 25 iliA when it is in standby (depend­ing on how many LEOs are on) and 200 rnAwhen it trips the relay. Not much power-s-andthat can be reduced by using the dot modedisplay if you desire. Sec below.

44 73 Amateur Radio tcaev » January 1997

o

"' *~,

a

"T I RI1 Ul

~ I

I ba

~ ® Ic

R13

c

Fig. 2. Modificu tioll for dot mode display.Connect T J us ",IW WII . Note: RII is N(I{ used ,

complete description or this circuit is given inthe original article. Briefly, the supply voltageis divided down by R4 and R5 and fed to pin5 of the LM3914. RL R2 and R3 arc usedwith the onboard voltage reference to set the ,low voltage limit at pin 4 and high voltagelimit at pin 6 . I tied pin 9 10 V+ to get a hal' I

mode display lor this project. When the sup- I

ply voltage is less than 11.4 volts, all LEOsarc off As the voltage rises from 11.4 10 15vails LEOs tum on from lclt to right. The •

higher the voltage the more LEOs arcon untilat 15 volts all the LEOs are on. Wilh 1% re-sisrors for Rl and R2, this is all accurate ex-pandcd scale voltmeter. I set R3 for ..ill LEDcurrent of about 4 mA to limit the power thatLM3914 would have to dissipate. IIwould. ofcourse, be possible to usc the dot mode in-stead of the bar mode, requiring only a smalldesign change for the low voltage input (sec"Alternative Circuits" below).

Whilc an LED voltmeter may sccrn ohso-lcte when fancydigital voltmeters arc readilyavailable on the surplus market. the LM3914

-.0 L

n~•30 AlIlp

N.O, Rda

/ 1\Rl4

® Q3

-. Vr- h

FigJ. Modificmion to lise NO rctuy, ReplaceNC retav between points A and Al ill Fig . J,with circuit shown,

\\)ltage Values Displayed byLM3914

LED. Turns When VoltageOn Reaches

LEDlIl 11.4 IIOlls

LEOll2 11.8

LEOll3 122

LEOll4 12.6

LEOll5 13.0

LEO" 13.4

LEOll7 13.8

LEOlla 14.2

LEO" 14.6

LEOll l 0 15.0

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Obtaining the parts and buiIding theproja1

which needs about 2 VOILS on its gate to con­duel This circuit will draw around 200 rnAbecause the relay coil is energized all thetirre. The eddirion of a simple SPST switchbetween the coil of KI and V+ will let youde-eoergizc the coil when you are not usingthe rig. You still get the voltage display fromthe lM3914and current draw isonly2S rnA.

I built theAVC part of the circuit in a smallRadio Sheck box and glued my modifKXl IT­T Tcster(still in its original Tic-Tee-box case)to it It may 001 look. elegant but it was quM:kard easy to buildand it WO'ks fmc.Afterall Iwanted to improve the circuit, 001 the

package!Parts are availableat the usual parts suppli­

ers. I stiII have pans (ircluding a PC bourdand 1% resistors, for the 11.4 to 15 volt range)and can supply the parts for the rest of the

project, except for a PC board, As Photo Cshows, the rest ofthecircuit is simple enoughthat it aut be easily made on a Ratio Shackuniversal bourd (#276-150).

T iny lie Tac Tester: All IXlJIS, PC board,imtructions-SI5.

(All resisto rs 1.4 watt 5% ,unless otherwise noted.)

Rl 7 .6 8k 1%

R2 3 .S3k 1%

R33 .2 k (1 .2k fixed and2 .0k pot)

R4 10 .0 k 1%

R5 S.Ok 1%

R6 24k

R7 15k

RS lOOk

R9 15k

RIO l k

Rll 24k

R12 15 k

R1 3 10k

R1 4 33k

R15 360 ohms

Cl .C2 1.0 ~F

Tl PN2907

T2 PN2907

0 1 2 N5061

0 2 IRFD020

Dl .D2 l N41 48

D3 1N4001

LED#l -l l LED.

PSI NC push-button

Parts List

If you want to build this project but don'twant to have to locate a high-current NC re­lay. you might do what I rust did. and usc the

Radio Sh:lckT" NO relay (275-226). To usctheNO relay it is necessary to modify ibc cir­cuit a bit See Fig.3. Q2 isa MOSFET whichis turned on wren QI is not conducting be­cause iLS gaic is high. This bolds the relayclosed When Q I oonducts, Q2 shuts offandthe relayopens.You migbr wonderwhy Q2 isaMOSFET and not an NPN transistor; QI isbasically a diode so wren itconducts the dropacross it is about 0.7 volts. This will not turn

off a transistor but will tum oIT a MOSFEf

Usinga normally open relay

73 Amateur Radio Today . January 1997 45

Contacts ha ve seve ral fa iluremodes. Overv ohagc can causethem to arc. j u st as in the plat eso f an ai r va r iable capaci tor.wh ich is e s sent ially wha t aswitch is when it's off. As youturn it on. t he co n tacts getcloser and closer togethe r. un­t il t h e voltage can breakthrough the ai r be tween themand arc over.

normal hook up wire. It 's o fte nimpo rtant for th e insu lati on tobe th in bec ause the ti ght wind­ings provi de maximum m ag­n e ti c ene rg y rran s te r. thusmaximum c fflc icnc y-c-but thatthi n ins ulat ion can break do wn

from excess voltage .E ssenti a ll y. th e adjac ent

wind ing s act l ike capac itorsbecause the two wires can, atany give n mome nt. be at d iffer­

e n t vottagc s as th e e ne rgymoves back a nd forth wi thinth e coil. Two cond ucto rs at d if­

ferent voltages. separated by aninsulato r (here. th e wires ' ins u­lat ion ) equal a capac itor, right?So , t he rule s fo r caps apply

here. as we ll as o the rs relatingto w ire itself (l ike metung t j.

Typically. co ils a nd trans ­fo rme rs bre ak down in t w oway s. Adjacent windings short

to e ac h o t he r, especially inhigh -voltage tran sformers, such

as the "fl y back" transfo rmersin TV sets and computer mom­to rs. Or, windings me lt, caus­ing a n ope n c irc ui t. Th at , o fcourse , is caused by excessivecurre nt heating the wire enough10 melt it. It happen s more of­

ten than you might imagine. Infact. it 's probahl y th e primarycause of transformer failure.

Although ext ern al heatin g isun likely to kill indu ctors. int er­na l he at ing is their ne mesis.Like res istors , thoug h. most in­ductor failures arc caused hyso me other c irc uit's pu lling toomuch curre nt throu gh the wire .And. odd ly. the damage ma y beo n the ot her s ide o f the mag­ne t ic circu i t ! M an y po w e rtransfo rmer primaries open af­te r so met hing short s out theo utput of the secondaries! Theseco ndaries themsel ves are o f­ten unharmed .

Switches and re la y s

Inducto rs

Co ils an d tran sformers aresubject to stress. too. M any aretightl y wound and have shellac

or something like it coated onthe wire for insulation. ratherthan th e p lastic j acket used on

Li k e a ll ca ps, va ria blc sshouldn' t get hot. Plast ic o nescan be leaky. hut it ' s rare. es­pe ciall y s ince they prett y muchnever huvc serious power ap­p l ie d to the m. A ir va riahle sonly leak if they become verygrimy o r oi ly, open ing a newpat h fro m one s ide 10 the o the r.Of course, if you arc an air va ri­able. it isn ' t go ing 10 stay cool!

External heat in g ca n kill aplast ic va riable . bUI gene rallynot an ai r variable . Ift hings gelhot eno ugh 10 melt metal p late s,

you have more to worry abour

than capacitors!

to arc o ver a ir ca ps. Plnsuc cap swill be ru in ed if the plast ic hasholes za pped through it , hut aircaps may survive. A n arced ai rc a p, tho ugh , will ha ve b urnmarks on it. and those areas willnot work as we ll as the normalmetal , result ing in a lcss-c ffi­cic nt ca p, Also . a hot e noug harc may actually melt the meta lplates, destroying the capacnor.lve see n pl ent y of arce d airvar iab le s in an ten na tu ne rs,though. and th at still see med towork fine.

Im port ant note : The vo ltageratings for caps arc no rmallyMated in volts DC. At radio fre ­quencies. the number mu st bederated (m ade s malle r) b)' afactor th at depe nd s on th e fre­quency o f ope rat ion-so don'tassu me a ton-vol t capacitor.... ill wit hs ta nd 100 volts of RF

at 146 \tHl ~ At such a high fre ­q uen c y, t he pan ma y bre akd own wirh perha p s o nly 30volts ac ross it. Cap manufactur­ers usuall y offer derating c hamth at show permtsstbr e voltagesat various frequen cies.

"If things get hot enough to melt metalplates you have more to worry about

than capacitors!"

.\to "" variable caps use eit he ra ir o r plastic fo r their ins ulat­ing layers. Air caps are nothi ngmore than plat e s w ith spacebe tween them ! They are fai rlyru gged. but the pl ates can bebe nt pre tty easily. making the msubject to mechanical stress. Ifthe plat es get too close to eachoth er, the cap wi ll he more sus -

Variable caps

External heal doesn't seem tobe mu ch of a proble m wit hthese caps. either. Th e plas ticinsulating layer ins ide couldmel t if things got reull.\"bliste r­ing. but that wo uld be an ex­treme ci rcu mstance. I haw seena co uple of o pen plastic capsnear big heal sinks. but not forman)' )'ears. I suspect th eir re ­liabil ity has increased over thelast 10 or 15 years .

Your Tech Answer Man

Number 46 on your FHdb/lck {:/Jrd

K RBOOMRSK

Sti ll More Stress

Michael J . Geier KBl UMclo 73 Magazine70 Route 202 NorthPeterborough NH 03458

W hen we le ft o ff. we we re

loo ki ng at capacitors . Theprob le m w it h ca ps is th a tthere are so ma ny diffe re ntkind s. it makes it hard to gen­e ral ize abo ut th e m ! So. le t ' sloo k at s t i ll a fe w more type so f caps.

Plastic capacitors. typicall ymade of polypro pyle ne or po ly-s tyrene. a rc u sed where lowdrift and accurat e capac itanceare req uired. Man y plastic capsco me in small. gree n. d ippedpac kages an d arc so me w hatrectangular, oncn with rounded

co rners. Inside the hard-dippedshell is a fo i l and pla sti c ar- ccptiblc to overvoltage arci ng .ra ngcmcrn that's wound in lay- And, of course, if the pla tescrs. at least in th e large r values. ac tually to uch those fro m theThe s tability o f p las t ic ca ps opposite side of the circui t. theco mes from the in he re nt stabil- c ap w ill become a cond uctor,iry o f the plast ic itsel f. wh ich and cease being a capac ito r atch anges i ts dime ns io n s and all!densit y ve ry l ill ie w ith te nt - Pl a st ic va r ia bl es a re le ssperatu re . prone to p la te bending be cau se

Plastic caps are \ ery ru gged . the plates are pushed up againstYou wo n' t break th em if you the pl astic. rather th an hanging

drop the rig. 10f course, if you free in space. T hey arc prettys it o n it. that' s another story.) hard to break, un less you tumTheir vo ltage ra t ings \'a ry fro m o ne so hard you tear the pias-around 50 vo lts 10 considerably tic. It's not easy to do .higher voltages. A s w ith any Whi le rece iver c ircu its usecap, yo u can blow ho le s in the suc h lo w vo ltages thai t he yin sulat ing layer wit h too much don ' t st res s variable caps. thevo ltage. vol tage rati ngs o f the parts must

No p la sti c c a p sho uld gel be carefully observed when thehot in norma l o pe ration. I' ve caps are used in transmiUers.Anever se en a leaky on e but , o f high SWR . or a tran sm itt ercourse . i t co uld happe n. As pushed to produce more powe rwit h an}' le ak}' cap , the re su lt - than it was built for, can raiseing curre nt n ow would heat the RF voltage high enough tou p the part. punch throug h pla st ic caps. o r

46 73 Amateur Radio Today . J a nuary 1997

Fo r th e la st few mo nt hs.we 've been discu ssing electri­cal . mechani cal a nd the rmalstress. examining how each af­feels various compone nts. Let'scontinue :

More caps

I' tI<.>r>e MKI- 27~ - 7.lH or hll _l·'1!4· UI.\~ . b \ X 'hll3-924- _S~13. or "'~ order f" rm 0" poge ~~for o, de, mg jof",,,,",,o,,

F ig . I . The milk -cartontelegraph key.

in to rosiness. Somctimes there's aproblem get ting the milk-cartonte legraph key to click. lf you don'tget a chck. move the electromag­net down a tiny bit at a lime untilyou 00.

For this display oftelegraph keysthai one of my classe s was work­ing on. the kids came up with agreat Kka. TIley tlOI only showed

al l the different rypesor bomenuccte legraph keys that were fun to

make. but they did some research.buill older models, and ind udedphotographs of some classics.

In a future column I'll show ph>­tos of the actual displays the childrenorganized. It was a wonderful pro.;t."l'tand it gave all ue kids a chance to

participate in cuntributing something

to thc display. rlJ

Leave six-inch end" to the wire .Remo ve the last inch of insula­tion from each end . and also fromthe ends o f the six- inc h piece.Wrap the alumi num foil aroundthe st rip you cut from the side ofthe canon. Then fasten it at the10 1' o f the milk canon . using abrass paper fastener. At the samelime attach one end of the wirefrom the electromagnet to thefastener, At this lime al so attachthe short piece o f wire to its fas­tene-r.

Now slip the dry cell imide themilk canon. Attach the other endof the sho rt wire 10 one pole of

Now the k ids in your cl asswi ll he ready to put a ll the te le­gra ph key, o n disp lay o r 10 pu tthe ir own te leg ra ph com pany

the dry cell . ;1Il0 the w ire fromthe e lectromagne t to th e otherpo le .

Attach the pa per d ip and abra ss fa ste ner to the c ut st r ipsat the s ide. Stick a small pieceo f cellophane tape over the pa ­pcr clip . Put the electromagnetin place wi th the e nd about one­q uart e r inch abo ve the papercl ip.

Displaying the keys

WITH CLRSS

--.., --­•

HRMS

"All the kids had a chance to participatein contributing something to the

display. "

Carole Perry WB2MGPMedia Mentors Inc.P.O. Box 131646S laten Island NY 10313-0006

Booksand TapesforBeginners

TAB~.154 Ilt'l(ln"'...·' 1I1t1~1..~.... "r A. n..h.....Rad'n ~y Clay La"" W~71'V .\'15 J'l!l"i ,I'.' nhful lu.. to. ...,"""..,.",. II ;, "",",' i\IWJW<ll illu., lnIN. E",n if l"'" ""'" aU k ~ ""'"_ .....,. JoOO'U >till fl>ld dtt> ,..., ",,-i-ul S21mW.'I(i""':-IV l"<I-(Vd< \ ldro. \ Ianwol. t'lorI <rIRu,,", b)' G<nk1n \\i~ l.-n 1>;... kl '" I twnr...."' If"'"....~ S~_9:'i

w~ v.....c T......riool ('1av,. I ......... .\"""'-l:_ No-C"""'-h).' Cam.. W"" Th;" 10."",- U'J\oI:R

""")llung j'lU """ 10.........'" I T,d... ....., aa..Ham. E"')' QIl'>lIOII m.l ""'....... 00 ""<UnlO'-''' " kllA1 in !hi> m. t.." il. RC IUnlMO~·......_S9.'l:'iXTJu.-1 Tho- er:-...... ...... .....-..... by 1'1IIIAarnl.. \\1IXI. Wall ~".... hi an""'UII~'Or ma~to.-~C:y>laI__ lib...""" fun.~., " ...td< ... .. raUd ...""~.... curuiI< l!IIIl~.,. hIIId Now IW1 ........_ OIUrftI Iun. ,"by? IJ3-. 110.9:5

Code Tapes73llli (~ ~ .. .......... ,-Tbo. l" paq• lIl= l"JU lho<q:tllb< ::'l'>"-" lO __"""~ p t•••l.....~ ...... rn<1ia'~ 1l<1' <f "Y 15.1'SnT!~ Tk~_hlpn"",- 11w.u ....;0."" up. b .. "t.., --..-l ., 5 "'l"'ll...., -.I il i> ahu .. "'" b ....~U' -.ITcd__ I~ It i<,,~ tlf.., ...Il_<f "'oll'. C1wa a , _ .... .. Il.p"-.I~ .. 5"'fQ \S 9:'imI l Rod IlnaLn- B ...... .- !apt Ctdt"...... _ . 1 trn.l l :l+ W(dIIO,.,.... be fnI~;II t_ ..in, JoO'I >II Woo" .. lio..of I~~

..........~ ..II<> ...... ..".., !"'O' ran~ ,Hi< . <ftIy B rn \S.9:'i

J II 7 h J h d 1Jn) C__ ;:0... .................. c.,....J'holo " . Alicia Kube lief0 an Diana Vasa a, t xrm e am ru io 1be~...... clits> Ilo.>:n<o:_ ~_9"i

still/ems . doing a presentation Oil telegnl/,h keys andbaneries, n-P.5 \ Ii..~:!5+- p- rodr . ~_9"i

73 Amateur Radio Today a January 1997 47

The Keys To Success

Construct ion

A s a fo llo w-up to previou scolumns w hich described variouste legraph key s that my ham ra­dio cras-es have had fun making.I' ll de scribe one that many MU­dents used for this year 's Science

Fair at our school. Most of thematerial s are easy to obtain so wedi dn ' t run into that as a problem.

Fo r this key yo u wi ll need : 10feel of insulated wire (commonlycall ed bell wire). a dry cell. athree-inc h by four- inc h piece o f

aluminum foil. three brass paperfaste ners. a large nail . a paperclip. and a milk carton.

First. cut away the top of thecarton. Then cut a piece one inchwide hy three inches long fro mthe center of a ile side of the car­ton . Next, cut the opposite side .

Cut a s ix-inch piece o f wi re (tobe used late r). T hen wrap the re­maindcr o f the wire around thenail 10 make an electromagnet.

Connectors

O ve rc urrc m ca n ac t ua llyweld contacts toget her! I usedto have a lin ear amplifie r whosepo wer switch d id that a ll theti me . The inru sh curre nt 10 thepowcr transformer was so hugethat. i f the switch contact s hap ­pened to to uc h right around themome nt th e AC po wer inpllt ' ,wa ve was a t maximu m. t heswi tc h wou ld we ld itself in the"on" po , it ion. requiring me topull the switc h o ut and breakthe contact:'> apa rt with a sere ....­driver (a fter unp lu ggi ng th eamp. of co urse ) ~ II used to hap­pe n o n ly abou t o nce i n ::!Otimes, but it was a pain in theneck .

Ref a y co n tac ts a re justswitc h co ntacts. so they sufferthe sa me problems. Contactsshould never gel hut. If the)' do.check the m for b lackening o rlo ss of plat ing. As long a, theresistance is nice and 10 w, s ig­nific ant heal if> nOI go ing 10ha ppen .

M uuy peopl e file contacts,bUI it is a cure somewhat wo rsethan the di sease. II will work

for a little while . hut the to'so f the pla t ing w hich occ u rswith f il ing usually leaves pu re

coppe r. and copper makes soft .eas i ly da maged sw i tc h co n­

tacts-that's why they plate thedarned lh ings in the fi rst place.

Filed contacts usua lly g.o hadaga in in vcry short order.

There arc so many k inds that

it' s hard to cla""ify the m . Nor­mally. connecto rs arc hardy. Ull ­

less you arc them ove r with wa y

too much voltage . Some insu­lat ing niate riuls used in RF ('(1Il '

necrors. though. can heat up iflo ts of power is applied. espe ­

cially a t ve ry high freque ncies.Afte r all . a connector j<, a ca ­pacitor. 100. what with il!> having IWO conductors se parated

by an ins ulator. It really pay sto observe power and frequencylimi ts fo r the variou s kind , of

co nnecto rs. and to always useconnecto rs appropriate fo r Ihepurpose .

Well. I think we've coveredthe slress issue prcuy well. Next

time. something different ! Unt ilthen. 73 from KBIUM. FZJ

it is wort h addi ng to the dig i­tal portion of my ha m stat inn.It appea rs to be ope rational,and I noticed thc d ig ital (RS­23 2) out put port o n the rearpa nel , thi nking perhaps itmig ht work wit h a co m puter­based station . I ha ve contactedDovetron fo r adv ice. and washung u p o n (twice) when Imentioned req ue st ing techn i­cal ass istance . So wi th hu rtfeeli ng s. I thoug ht of askingyou for advice. Should I kee pt his thing or cannibalize it?'!T han ks in advance. Do ct o r.and my hcst 73!!"'

Well, Neil, the Do veiron te rmi­na l units have been quite popu­lar for many years . and I wou ldhe surprised if it wou ld not do youwell. I understand the need fordocumentation , though. even ifthe folks at Dovctron do not. So,I turn to the readership of this col­umn. Anybody? If so. drop me anote, or direct the information toNeil directly. I know you won'tlet me down.

O f course . when it comes toonli ne so urces , yo u c an't gowrong surfing on over via theImemct to the RTTY Loop HomePage. l have been doing so me up­grades and am tr yin g 10 p utsome of the programs you have

Fig. J.

Soft-

r e c e n tl yp u r c h a se d aDovetronTe r minalUn it. and I'mwo nd eri ng i f

cu rrent ly ava ilahle. T he re isalso a live co nfere nce area .wh ich spo nsors o nli ne chats.gian t cybcrwor td Q SOs , onvarious ha m radio topics .

Although th ese onl ine se r­vices were once quite ex pen­sive, r e c e n t ly in t rod ucedeconomy and fl at rate pricingstruc tu res have made usingC IS and AOL m uc h more at­tractive . If you arc on o ne ofthese services, why not take alook at the ham radio boards ,

if you have not alre ad y. Forsome use rs , these re prese nt anatt racti vc alternate \0 othertypes of onli ne provi ders.

An ex ample

Wh ile online, I rec eived amessag e o nCo mp uScrvefro m S. :"Jei lXe ni as:"J4CTB, whoposed the fol­lo win g ques ­t ion : "I have

sages scrollo ff the systema fter a while .AO L seemsto hold themo nline form uch longer,makin gsearches oftopics a n dthreads a hiteaster.

Theirware Exchange, F ig, 2.shown in Fig. 6, supports file li ­braries for a varie ty of sys­tems . Even the Macintosh ,w h ic h seems poorly repre­se nted on some systems . has asection; F ig . 7 shows what is

_ j.,

America Online

A lt h o u g h qu i te a hi tyounger, A me rica On li ne hasmade quite a name fo r itself.and has q uite a nice amate urradi o sec t io n, as well. •.'ig. 4shows the entrance screen fort h e i r Ham Ra dio Club,r c ac h c d w it h t h e keywordHa m Rad io . T here are quite afe w fea tures. as can he seen.althoug h the AR RL section isa tad dated, wit h in fo rmation

many mo nthsold on line.

J ust as withCompuServe ,a message sec­t io n is avai l­able. as shownin Fig. 5. witha variety nft opics a ndroom for thou ­sands of mes­

sages. Unli keComp u.Sc rve.where mc s .

system. with a hrcad th that ishard to heat. You do n ' t needthe latest access program tousc the service-the conten t isthe same no matt er which dooryou come 111.

that question or puzz le that in­tcrcsts you. It is l ike ly the an ­swer will h e the re the nexttime yo u check in.

A similar range of to pic s iscove red by the file lihraries,show n in Ftg , 3 . With 23 sec­ti o ns of informat ion and hun­d red s of fil e s ava jlable , this isorten the First place to find thelatest re lease or update of h amrad io so ftware .

Ove r the years. I have al­ways fo und a wide variety o fmaterial on the Co mpuSc rve

Number 48 on your Feedbad C/Jrd

"Recently-introduced economy and flat ratepricing structures have made using CIS and

AOL much more attractive."

Amateur Radio Teletype

Fig. I .

48 73 Amateur Radio Today· January 1997

The granddad dy of onlineservices, CompuServe , has rc­cen tly revamped its in terfaceand . with CompuServe .1.0.1as an access program. the ser­vice has a ncw face . i f not newconten t. T he a mateur r ad iose gmcnt of Compuscrvc canbe reached by t h e GOH A rvl NET command. Fig. Ishows t he opening screen ofthis venerable resource.

Fig . 2 shows the variety oftopics covered in the messagesection. ranging fro m scannersto pac ket to compan y-specificinformation. Wit hin each sec­t io n are a few to do zeus o fmessages dealing w ith awide ra n g e of infor mation.T his is a good place to post

Marc I. l eavey, M.D., WA3AJRP. O. Box 473Stevenson MD 21153

Comp uServe

As has b c c n my customthese past 20 years of " RTTYLoop," let me he among thefirs t to wish each and everyone of you a Happy New Ye ar !May this year he one of hea lth ,success, and peace for us ull.

We have been discussing . oflate . a ll of the latest computerprograms ava ilah le for radioteletype, pac kc t , and otherdig ital forms of com munica ­tio n. One ques tion often askedis where these programs maybe found . This month . here 'sa look at t ....'() ma ssive onlinesources.

Brrv LOOP

->

....... 1<_Ulr... IIlt .....• _ R _ lJInry lllt .. _ .._~....D06'•••• •_.. 11• • • L ,., .~• _ R LIlnOY. S._R__ ",..._.•_-.....

-,0 _0_ 'D~_

D~"0 _0' _0 _0 > _ '----- - ---------"

F ig . 6

•

t:-- - -...." ,"'-,"", '" " ",- _"" e..... '.. " n O'~. ........_"" ,,' ".

~ ! ~. ..._,.,--- ., ".-, '__' .... 0 .. ".~, _._n.... ., ...-,-_...... .. ".• -, _.._ '..... •• ,-• -, -....._ '..... ., ".• .~ _ I I • ., _.I: ...' ...-.." ..,_... • ...- '_ "_ e-" , ,,, ".-, ...._,.. - ...• _. ...... . ._ w • •••• _..- • .-• -,•__.:0.,. ,. .-• _._n.._ • _.• _._ J• • .., • ".or • •• • ,

-~ ~ ~ ~ @]-- - ---Fig. 7.

as ked about up fo r download­ing, as well as links to man yham radio s ite s o n theWorl d Wide We b, a nd thereare many. many ham sites !Stop by the page a t http :"www 2.ari .nellaj r/rnyJ and seeif you can't find something in­teresting. If you have . or knowof. an amateu r radi o re lat edsite, drop me a line and let meknow, so thai we can establisha crossl in k. Spea king oflinks and webs. I plan somean tenna wo rk thi s fa ll andwinter, when the trees arc he­reft o f th e ir fo l iage . Sta ytuned- those o f you who re­member my ex plo it s with abow and arrow a few yearsback won' t wa nt to miss thisone!

So. let me hear from yo u,via mail . or via E-mail a t ajr@ari.ncl , or Marc WA3 A JRon

AOL. or 75036,250 1 on

Compu- Serve . You are all panof this col um n, and I do l ove

hearing from each o f you . fa

[I]_.-

~--

f".l~----

,,­,,­,,­,,­,,­,,-..... ,_..

, Iiiil~; ~~- -- -

"'''-OiUHIU1U'

~._-.- ­_......--

•• •

i llIoo "*- _ "010 __~...lJt.I""" _ - , _ ,,_

FigA.

Fig. 5.

"The H am Radio C l ub8T...Y1\.NED. r>t_Ol _ ,_.._ __ .... _ I'I_c.....

I ~-~--c c. _ .... ,__c _ _ , •0 _"_0:-c c "-c~.0 ,.... 1'1_c _ , ,1'1_0_

"US Patent Granted

Imagine, a full featured HF Transceiver with a patented"built-in keyboard interlace. Just plug in the keyboard(included) and enjoy CWIRTTY Data Communications.

A WHOLE NEW WORLD OF HAM RAOIO IS HERE NOWI

ADVANCED FEATURES:• Power Output: Adjustable 1 to 100 Watts

(160 thru 10 Meter Ham Bands)

• DSP Filtering System:Incfudes:

• 204Khz. 1.8Khz. 500Hz. 250Hz and RTIY~Brick Wall- OSP Filters

• OS? Au10n0tch Filter for SSB• DSP "Denoiser" Reduces Background Noise

• General Coverctge Dual Conversion Receiver(1.5-29.9 MhZ) USB, LSB. eN, RTIY and AM

• Collins Mechanical Filters Included• Highly Effective Noise Blanker

• IF Shift• Built-In Digital Powefl'SWR Meter• Built·ln Iambic Keyer (5-75 WPM)• 100 Memones Plus scatctcac• Selectable Tuning Speed; Fixed and Variable• Built-In Keyboard Interlace (Keyboard Included)• Front Panel Selection of 3 Antenna Inputs• RS-232 Port(s) for 'Dumb terrnmar" Display• Manual Notch for CW and RTIY Modes

Designed and Manufactured in the U.S.A.

Phone; (516) 862·65t2 . Fax: (516) 862-65297 Flowerlield M100. St. James, NY 11780

CIRCLE 321 ON READER SERVICE CARD

73 Amateur Radio Today . January 1997 49

NumbM 50 on your FHdbM;,. Cllrd

[RRR'S CORNER

"The winners will each receive one oftwo crystal glass trophies generously

provided by the Waterford CrystalCompany. "

Joseph J . Carr K41PVP.O. Box 1099Falls Church VA 22041

Some Potpourri : WannaMake History?

wauna hel p make history and00 '>(IIIK' VHF ha mming. in the b ar­gain" Or ho w about ho mlring: his­tory, making. some history and

do ing '>()!llC' neat hamming? All arcpos-iblc. allhoug.h u's going to toepretty hard .lbe lri..h RaUtu Trans­minersSociety ( IRTS) announceda comcv last year Ii .... Ill.:: first Ir.UlS­

inhume ham communication on 2meters.

The winners will each receiveone 01' Iwo crystal g lass trophiesge ne ro us ly pro vide d h y the

Wate rford C rys ta l Co mpa ny,Wn..l!oC products are known world­

wide . In fact. if you've bought anyufthal stuff you·1I kn ow that a cus-

tom piece ofWaterford is a line andexpensive pr ize indeed ! Wate rford

C rystal. alt er all. is {l[1C (I f the tin­

est producers of crystal g lasswarein the world (and an Ir ish ico n).

Tbe crystal trophies arc cal led

lhe Brendan Trophies. anenbe leg­-c nda ry Ir is h fo lk hero . Saint

Brendan. Among the Irish. he isprohahly seco nd o nly 10 SaintP:.llril·k. amI is o lk n rd em.'(j to as

" Brendall lhc Bold: · And why was

Saint Brcnd~m so hold? Wel l. if histrave ls. chronicled in NaI'iSHl;o

Urendall; (Tilt' VOyll !oi e ,1 ofUrelldllll ). arc actually history in­~t eild of folk tales and storytelling.

t ~l1 lk' may well ha \ e sai led to the

easl coast o f :'Iiorlh America­

tmnsallanlic-in the e nd of the

fifth. or t-ocginning of the si:\th. cen­

tury A.D .... in a leal~r !xxII ! lnereis ahout as much t ime belween

Brendan and Leif Ericson . who

also apparently made Ihe journey.as there is t-octween I~ lirsl English

settleme nts in North Anwrica ,md

WayTIC Green's birthday. In ot he r

word... or Brendan was a prettyearl y traveler to North America. if

the stories are true.Interna l e vidence of the legend

suggests that he probably reachedIce la nd Of Greenla nd. and possi­

h ly Nova Scotia, nearly hal f a mil­

lennium before Lei f Ericson. Thestories date 10 lhal time, and haveverjfiable facts. or atleast suggcs­lio ns of facns. That Brendan's feat

is at least possible was proved in1976 by Tim S everin , who re­

peated the journey in a lcarber boa!

ot tmdmonal design, If you are onc

to bend an elbow in honor of Ihebo ld (or the foo lish), the n St.

Brendan's feast day is May loth

eac h year.Fo r radio signals, the North AI­

la mic path has al ways been some­

thing o f a challenge because il

crosses magnetic lines of fo rce at

high latitudes. and is bombarded

with assorted troubles such as the

aurora. particles an d radiation fromspace , Indeed. "someth ing o f a

chal lenge" often means downright

dillieuh.The short- term radio propaga­

tion coodiuon predictions are U$U·

al ly made for the North Atlanticpath because it describes nearly­wors l -case condi l ions. Anionosonde de\'ice tests the path

between the cont inenls. and thaI

d11a is puhlis tll-d on rad io s!alionssuch as WW V.

Marconi was the first to cmssIhe Atlantic on a radio " \xlat" ..,

abo ut a mille nnium and a half af·te r Brendan and a millennium af­

ter le iI' ( by Ihe way. I kno w a

t'o rwegian lady who ce le hratesOclol;Jcr 12th not as Columbus

Da y, but as Leif Ericson Da y).

\Iarconi probably used LF fre ­quencies. which were more prac­

tical than the 1>honwa\'Cs in tlMlse

days, to tr.lIlsmit the \1o rse codelet!e r "S" fro m the west coast o f

England 10 a receiving sill' near

S I. John s , Newfoundland. in

December 1903.It took another 20 years for tbc

shortwa ve radio to C'TIJ5S the Atlnn­

tic. On the night o f 27 x ovember.1923 , the contact was establishedby ham radio Opcr.tIOTS .., and it

startled the world! Today. anyone

with a fe w walls loaded into a wetstring ante nna can work transatla n­tic contacts with case. I recall oneo ld fello w who gave ham cl ubspeeches o n early rad io , ha ving:

been one o f the ti rsl post-war. i.e.post-World War I. hams 10 he li­

censed. In about 1960. he came 10

the Potomac Val ley Radio Cluh. of

which I was a member and 1!a\'C. -us a talk. (Personal 0011,,' : FonnerA R RL Presidem Vic Cl arkW4KFC picked me up for meet­ings ; because I am an epileptic I

could no t med ically quali fy for adriver's license un til I was 23. ) Heto ld us how they were using fre­

quencies as close 10 200 meterswavelength (around 1.500 kIll: in

the A~t BCB 10 our present-day

160 meier ham band) a" possible .

The HF frequencies we re consid­ered use less ( w hic h is wh at

prom pted the famous ".; 200meters and down" starcmcru lhal

isenshrined in Clinton B. DeSoIO'S

book of the same title). The an­tenna was stru ng out across hisfather's Pied mo nt Virginia farm,

and was one of those three -wire

fl at -tops that ran about 600 10

1,000 fee t down the meadow,"OX" .was any statio n IwO sta tes

away.

In 192~ , he went away to the

University of Virginia 101>tudy en­

g ineering. and le ft lite ham slat ioo

to his younger brother. When he

re turned for T ha nksg i \'ing , henoted Ihal lhe flat -top ,mlenna wa..

gone, and was replaced w ilh a

couple of pUlly liule th ings be­

tween 60 and 120 feel long. lIis

brOlher sheepishly told him " we

arc using Ihe shon waves nnw."

Skeplical , the fell o w dec ided to

send a message to his f(X1I11 male.

who lived in Ohio. So. heari ng a

station .... ith an "8:u" callsign ( I~)

didn't use national designators in

Iho se d ays . so one-by -Iw ocallsigns such a... " IA\\~·-H i r.tm

Percy Ma.'(im·s callsign before il

becmrn: " W IAW"-werc used) hea.<;kcd Ihe g uy 10 relay the me~<;;)ge

to Canton, 0 11. "Sure, 0 .\-1,1'11 he

glad 10. hut you arc probably in atcucr posltion ro relay it yourself

than me because I am FRE....C H

xxx." He dam ncar fe ll o ff hischair! His first OX was e ver the

supposed ly intractable Atla ntic

Ocean. with lillie more Ihan 15walls o f power,

Now. bad . to the Bre ndanAward. Some people cluim tbnt the

2 meter Transat lantic Challenge

spo nso red hy IRT S will he a

greater technical achievementthanMa rconi's 190 3 wor], ... so here's

yo ur chance for immortalit y The

award will go 10the fi N two a ma­teur radio sranon...... ho eSlahlish

two- wa y con tact o n 2 meters .

across tbe Atlanlic ocean. without

using a satellite or earth-moon­eanh( E.\ tE) mcthtMb .That would

he cheating!Both srenons must be physically

located on la nd. or o n non- tidal

waterways, with in the boundariesesta blished hy the conti nental

s hel ves of Europe and No rt h

America. Each o perator must toeproperly licensed .IS all amateurradio operator by his or her na­tional govcmrrent. and he operat­

ing within the provisions of lhal

lice nse tespccially power and fre­quency limits ). IRTS reserves the

right 10 have its representati vesinspect bor n claimants" ..tations

to e nsure uuu things are on theup-and-up.

T he norma l ru les for an cs tab­

lished ha m QSO apply to the 2me te r T ra nsat la nt ic C halle nge ,

Bot h ~ta lions must rece ive the

calls ign of the other in full: signa!

reports must he e xc hanged (a ny

recognized s ys Il."m- RS. RST.

meteor scancr-ccan toe used. hut

il r nusr inc lude at leil~1 two char­

acte r.;): each slation musl rccei\'e

co n fi rmal io n ( ~ Ior se " Q SL:'

" R" or voice " Rogd' ) from thc

othe r. T he dat a mu s l he ex ­

c han ged within a s ingle fo ur­

hour pe rio d. If the fo ur- hour

p..:riod exp ires , t tll' n a ne ....' con­

tact - pai r (a no the r fou r-hou r

pcrilxl ) must he cst:lhlished.

In something: o f a "shades o f

\ 1an.-oni" e lTo n. tlte Rad io Sod­

e t)' o f Greal Bril a in (La mbda

House , Cmnhome Road. Pollers

Bar. He n s., F...... 6 3JE. England) is

scll ing up a special ,leCOOIll for

donat ions to ils RSGB Pru pagationStud ies Co ntmiul'C to allo w the e,,­

tahlishmCIll o f perm;U1crtl beaco ns

50 73 Amateur Radio Today -January 1997

Connections ,__

I can be reached via snail mailat P.O. Box 1099, Falls Church.VA 22{)..t I, or via Internet Ecmail

at canjj@aol.com. fa

yourself. Teachers, after all,arc largely dedicated to theirprofession, and will performad mi rably 10 mentor younghams-wannabees and help themget licensed. Pull ing a liule ef­fon into j unior and senior highschools, not to mention the up·per end of the e leme nt arygrades, will pay rich dividendsfor the hobby.

Ho w import ant is gelli ngmore li fet i me hams into thehobby? Radio spectrum is pre­cious. and there is a simple rulein effect: Usc it or lose it. Re­member, the I I meter Ci tizen 'sBand was a ham band pre-1957.We lost it to the Class 0 CDservice because the FCC couldsee that very few people wereus ing it .. . the 1956 or 195 7"Save I I" contest at the las tminute notwithstanding.

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for sudden increases in signallevel). and propagation sndes tes­pecially during solar eclipses orother solar events). Ham radio canbe "snuck into" such activi ties.

Still another way is to findand encourage schoolteacherswho want to get into ham radiothemse lves . Mentor them , getthem licensed, and help themse t up a stat ion. You do thatwith newhies anyway, so whynot concentrate some advent s­ing for your club's Novice cl asson the local schools? I recall aseminary professor who taughtat a schoo l that had a large con­tingent of Third World stude ntson scholarship. He said the rea­son was that it cost $25,000 ayear to keep a missionary intho se cou nt ri e s , bu t o n lySIO,(X)() a year to educate a na­ti onal ... who would go backho me an d re mai n in p laceteaching for many, many de­cades (at no additional cost oreffort). The same pri nciple ap­pl ies for hams: Teach a teacherhow to "fish" and you won' thave to feed his or her students

'''"''&IT/II'

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42-50 MhzGE EXEC n , l DOW, Xtal. $99GE MASTER II. l DOW, Xtal, $1 25GE DELTA, 100W, S)TI, $1 99·MICOR, WOW, Xtal, $99MrIREK, 1DOW, Xtal, $125

406 - 420 Mhz 450 ·470GE PHOENIX, Syn, $189 GE EXEC II, 40W, Xtal,$ 185 ·OE MLS, Sy, $99 GE MVP, 40W, Xtal,SI85*STANDARD GX3000, Syn,$129 GE MASTER II, 40W, $199 ·STANDARD IIX400, Syn, $75 MORE, MORE, CALL!!Accessories, ifany. arc optional. Testing available at additional costCall or ....ri te for full product information. "Testing included.30 dlily warranty on lrstll'd Items,

but another big bunch is doingsome real science (unfonunatcly,I won' t he able to judge too manyscience fairs thisyearbecause I amleaching a NonhernVIlginia Com­munity Co llege class in VisualBAS IC on Saturday mornings).

The point of this digression isthat we hams have an opportunityto hook kids into the hobby at anearlyage through education.Therearc a couple of ways to go aboutthis (besides reading "Hams WithClass"). First, you can mentor (or

is that "Elmer"?) youngsters \10 00show interest in radio. That's howI got started (Mac Parker W41Jwas mine), and I suspect it's howmany of you-all got start ed aswell).Anotherway is to work withhigh school and junior highschoolscience fairs,or volunteer to workwith the science departments.

In some schools. they permitcollege-dcgrced members of thecommunity to teach scie nce

classes. although under thesu- r-;:::=======::::::::=::::==::::::::===::::====::::~pervisionofa licensed teacher.That's a possibility for bothcommunity involvement and(in some cases) a lmle (verylitt le, sadly) extra income. Inot her cases, e ven no n-degreed people with indus­tri al a rt s expe ri ence <Ireallowed to leach shop classes(again, under a lice nsedteache r' s supervision). Anau to mec hanic I kn o wteaches a two-hour sho pclass every day at the localvee-tech school (a hig hschool with an industrialart s flavor].

You can alSOSCl updemon­strations of ham radio for theschool, or serve as a commu­nity advisoror mentor to a stu­dent ham radioclub (I've seenboth done).

Still another taeticwould beto beco me fa miliar withradiosclerce observing, andintegrate ham radio into it.This act ivity includes lookingfor natural radio signals suchas whistlers t l to 10 kHz), sed­den ionospheric disturbances(SIOs) caused by solar flares(these are found by monitor-ing 15 to 30 kHl VLF stations

"Here's your chance for immortality."

"Hams With Class"

on 2 meters. One beacon will helocated near Lands End, England,and theother near St. Johns, New­foundland. That project could re­sult in some substantialprupagalion studies, andcould leadto the information that will causesomeone-or more than onesomeonc-to win the St. BrendanTrophy.

For a good source of technicalinformation on the prohlems of 2meter transatlantic propagation,check out " How To Win The

Brendan Trophies" by Dr.Geoffrey H. Grayer in the June1995 issue of Radio Communica­lions (RadCom is thejournal ofthcRSGB, and thus enjoys a positionsimilar to the ARRL's Q5TamongBritish ham operators). The ad­dress for RadCom is the same asfor the RSGB above).

The Brendan challenge is notimpossible, but it would be verydifficult. One of my earliest hamwrit ing tasks was the momhly re­port of the Nonhern Virginia Ra­dio Club (club station W4PAY) tothe Foundation fo r AmateurRadio's Autoca/l newsletter. As aresult of that task, I received aninvitation to the 1960 EdisonAward (sponsored by GeneralElectric) banquet in Washington,DC.The two fellows who won theaward thai year had establishedtwo-way ham contact on 2 metersbetween California and Hawaii.Not exac tly the Nonh Atlanticpath, but about as far (although Iwould prefer being in KfI~land

than in any location in the NorthAtlantic ... save only El-lard andGlOM-land, for which I have aspecial fondness).

One of my favorite ham col­umns has bee n " Hams With Class"

in 73, partially because I have asoft spot for people who work withkids and introduce them 10 radioin general and ham radio in par­ticular. Every year I judge severalscence fairs, and am impressedwith the ability of kids to do sci­enceand techoology.Alotof themare little more than re-doing class­room demonstrations, or worse,

73 Amateur Radio Today' January 1997 51

HAMSATSNumber 52 on your FNdlYCII card

Amateur Radio Via SatellitesAndy MacAllister WASZIB14714 Knights Way Drive

doing well. When the satellite isHouston TX 77083properly illuminated. signals arcgood .

Good News-Bad News Phase 3-D coming soon

We start the new year wit houtA mateur radio's next major

satellite is sched uled for launch inAMSAT-OSCA R- 13. This high- April 191)7. Named " Phase 3-D:'orbi I . long -life sa ten i l l' w"' thi-, satellite is the largest. mostlaunched in June 1988. Since complex. and most ex pensivethen it provided hamsar enthus i- ham-radio satell ite n cr huilt.asts quality high-tech communi- Volunteers in O\'eT a dozen coun-ca t ions fo r over e ight yea rs tries on five corntncnts have bee nbefore succumbi ng 10 the- gra vi- .....orking for years 10 bring thi stanonal effect s of bodies beyond

projec t to fruit ion.the earth. Most sate ll ites in ellip- The launch is to be the secondtical orbits with a perigee. or low ever for the new Arianc 5 rocket.point. of thousands of miles will The first Ariane 5 failed in Junestay in orbit for hundreds. if not 1996 , Correc ti on s ha ve hc e nthousands. of years, Due 10 the made. tests have been run, andorientat ion o f A~O- I J's orb it . optim ism is high for the secondthi s was not the case. T he forces Iligh t. Phase J -D wi ll be sent upof nature took over and its pre-

with a pair of technological mea-mature end was inevitable as its suretueru packages for validationperigee was pulled closer 10 the of the launch vehicle' s ability toearth b)' the sun and moon. place two satell ites into a geosra-

On the posit ive s ide. A-0-1 3 tiouary transfer orbit.perfo rmed e xtre mel y well After launch. Phase 3-D willwhil e '" orbit. A MS AT-

become an O SCAR (Orb itingOSC,\ R-IO. while not as func-

Satel lite Carrying Amateur Ra-t ional as A-O-13 was before rc-

dio ) and will begin a period ofentry. st ill pro vides high-orbit,

tes ting a nd orbita l adj ustm entMode " 13" (70 em up link and 2 that may last months,me te r downlink) operat ion al-most 13 years after launch. Be- In the m e a n ti m e ...fore launch. A~O- IO wa s knownus Phase 3-B, 11 was the second Wait ing for the new h igh-or-Pha se 3 hamsar. Its predecessor. hit sate ll ite needn't be d ull. WePhase 3-A, never made it into or- have over a dozen operation al

bit due to a rocket ma lfunction LEO (low earth orbit) hamsmsin early 1980. Excellent long-dis- in orhit available for use fo ur

ranee contacts are still poss ible to six rimes a day each . any-through A-o- I0 when conditions where o n earth . Frequ en c iesarc right. The on-hoard computer used o n the se sa te ll ites ran ge11 0 longer works. hu t the Mode all the way from the 2 1 :\1Hz"B" radios and the solar cells are uplin k of RS-1 2 to the 2400

Uplinks Channel A 145.81 5 MHz - 1200 baud AX.25 FSK

Channel B 145.835 MHz - 1200 baud AX.25 FSK

Channel C 145,855 MHz - 1200 baud AX.25 FSK

Channel 0 145.875 MHz - 1200 baud AX.25 FSK

Downlinks UHF TX1 437.206 MHz - 1200 baud AX.25 BPSK

UHF TX2 437.1 38 MHz· 1200 baud AX.25 BPSK

Table I . 8(/1/(/ phil! for Mexico-OSCAR-30.

52 73 Amateur Radio Today - uenuarv 1997

:\-IH z d o wn lin k beaco n o fDo\'e-OSCA R-1 7. T he re is agood mix of d igita l and a nalog(m ice/C W ) satell ites available .We have new sate ll ites li keFuji-OSCAR -29. launched onlya few months ago. to o lder sa t­e lli tes incl ud in g UoSAT-OS­CA R- II la unc hed in M arch

19 84.

The South Afric a AM$ATAward

In a cooperative effort withSouthe rn A frica A 'tSAT. th eRadio Amateur Satellit eC orporat ion ( A M S AT- ;'I;or l hAm er ic a ) is p ro mot lng th eSouth Africa A:\ISAT SatelliteCommunicat ion Achie vement

Award . T his award is the per­fe e t e nt ry- Ic ve l aw ard fo rsa tc ll ite enthu s ias ts . T he rc­quircmcms arc simple. Send 25QSL s (or good fro nt and backphotocopies ) for Phasc-2 ( lowearth orbit] sa tc ll ite contact s 10

the A '-ISAT Awards Manager.The fee is S3.50 fo r A MSATmembers a nd $5.00 fo r non ­members. Additional funds arcrequested for thc return of QSLca rds if photoco pi e s are notsub mit ted . Send to: A'-1SATAward s Manage r. ~1 i k e

Scarcella WA5TWT. 3 10 Lom­hardy. Sugar Lan d, TX 77-t7 8.M ike has been authorized 10 is ·sue the Sout h Afric an awa rdwithou t the lo ng delays prcvi­o us ly encounte red wi th over­seas submission. The low-moilbamsnrs can be a lo t of fun.

A New Year's event

For man)' years the ARRLhas spo ns ore d Straight Ke y:'Ilight (S KS ) on S ew YearsD a y. Ray So ifer W2 RS in ­

v ites inte re sted sa te ll ite o p­erators to part ic ipate in the25th a nnua l S KN via O SC AR .

He repo rts that th ere arc noru les , no sco ri ng . a nd no needto send in a log . J us t c all C QS K:\ in the C W passband seg­ment of an OSCA R be twe en0000 and 2359 UT C o n J an u­ary I. 1997 , o r ans wer a CQSK:-'; ca ll from a nothe r st a­t ion. Contact s via the moon

a lso co unt. Ra y refe rs to themoon a s OSCAR -D. No m ina ­tions fo r the be st "fist" can he

se n t vi a t he Inte rn e t tow2rs @amsat .org.

An end before abeginnin g ?

Less than a month after the sue­ccssfulleurcb of Fuji -OSCAR-19.'1exico-OSC AR -30 ( \1-0-30)wa s successfully placed in orbitfro m the Ru ss ian Ptcsctsk faci l­ity on September 5, 1996, Thesatell ite's po la r orhit is j ust un ­der I .OIX) kilometers (bOO miles)

high. Signals from the sate llitewere re c e ived s ho rt ly a ft e rlaunch. bUI there is a problem.The si gnals disappeared afterse veral days and attempt s tocommand the vare tlue failed.Work continues in an attempt tohring M-D-30 bal'k to li fe. butcatastrophic failure in the co m­mand receiver is feared .

Prior 10 launc h. the new satel­lite was called LJ l'\A MS AT-B.T h is was 11 tH th e f ir s tUNAr>.t SAT. hut rather the re ­ptacc m cn t fo r U/'\AMS AT-lwhich never achieved orbit. TheUNAMSAT- Ilaunch att empt ona co nve n ed Soviet SS-25(TOPOl) missile met a ficryendwhen an upper-stage motor fa iledo n March 28. 1995. Foll ow ingthe d isast er. the U f' A MS ATn ew was dejected hut not with­out hope . Two sets o f spacecraftmodules were originally buil l.

While lJNAM SAT-1 lay in a

mass of rocket debris somewherein eastern Russ ia or on the bot­to m of the Sea of Okhotsk, theback-up mod ules we re wa ilingsafely back in thc lab in MexicoCity. It took a lot o f work o ver anne-year period to gel the secondUNA '-ISAT read y-to buy newsola r panel s and ge t anotherticket to orbn . Project DirectorDa vid Liberman XEI TU pro­vided the needed drive .UNA~1SAT- B rep rese nts thenever-say-d ie a t titude o f truespace pioneers.

UNAM$AT-B

Bu ilt at the Unive rvid ad~acional Autonoma de Mexicohy t he PU IDl: ( Prog ra mau r uversnano de lnvcstigacion yDesarrollo Espaclal. or Univer­sity Program of Space Researchand De velopm ent ) grou p.UNA:\1SAT.. U i~ the most recent

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73 Amateur Radio Today • January 1997 53

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T he fre que nc ie s shown inTable 1 define the Mode "J"communica tions capabi lities ofM-O-30 . The following data wasreceived b y Norbert NotthoffDF5DP a few days after launchon the 70 cm downl ink before thesatelli te went silent:

Doppler sh ift is detected be­tween the samples (indicatingrelative me teor speed). the ra ­dar transmit ter will be set for afaster pulse repetition rate fora period o f time . Data that rep­resents meteors traveling abovethe 72 kmlsee speed lim it willbe logged and stored in file s.

The TSFR module

th in quartz crystal coating. The2 meter antenna is on the top,while the 70 cm antennas are at­

ranged around the bottom. The41 MH z antenna is a canteddipole.

micro sat "clone." Th e fir s tmtcrosars were lau nc hed sixyean ago from French Gu iana.They are small cubes. 25 cm ona side. we ighing about 10 kgeach. with five internal stackedmodules. Four of the modulescontain standard systems com­mon to all AMSAT micrusats: afive- channel 2 meter rece iver,battery charge regu lator uni t,computer and 70 ern transmitter.The fifth module in the stack iscalled the TSFR, or 'This SpaceFor Rent." The TSFR in M· D-30contains an intriguing e xperi­ment to identify me teors thathave velocities greater than 72kmlsec.

The five-channel. 2 meter re­ce iver was designed for d igital(I 200 baud FS KAX .25) uplinksfrom users on four simultaneouschanne ls : 145. 8 15 , 145 .835 ,145.855 and 145.875 MHz. Thefi fth channel is the unpublisheduplink for ground-based controlstations. it is used to send so ft ­ware up to the sate lli te andchange onboard o perational pa­rameters. A failure in the com­mand receiver is o ne o f thepossible reasons for M·D-30·ssilence.

The BCR module, or batterycharge regulator, contains notonly the power control circuitry,but also the nickel-cadmium bat­teries that allow the sate llite tooperate during eel ipse periods.

The computer module uses aradi ation-hardened NEC V40microprocessor. Thcreis al'lOa256Kbyte bank of EDAC rrcmory aOOan addit ional 4 Mhyte hank ofSRAM. Total com puter-systempower consumption is und er Iwatt.

The transmitter module con­tains two separate UHFtmltsmit­ters for te lem e try andcommunications downlink. Bothusc BPSK (hi- phase shift keying)modulation at 1200 baud. AX.25protocol. The primary transmit­ter is on 437.206 MHz, and thesecondary transmitter is set to437.138 MHz. Onl y one trans­mitter at a time is act ivated, buteither can be used for all telem­etry and data communicatio npurposes.

The body of the satellite is sur­rounded by high-efficiency gal­lium-arsenide solar cells and a

Number S4 on your FfWdback card

Your Input Welcome Here

HRM TO HRMdisadvantages: You must take ex­Ira care to properly waterproofyouroutside co nnectors (since any inter­nal water wil1 l1o ....' ca....ily throughits mostly air-fi lled innards) but youshould carefully waterproof all out­side connectors anyway. Al so ,991 3 is nor quite as flexible a" RG·213. since the center conductor isa so lid copper cond uctor, Astranded center conductor form of99 13 is available, btUif" a hit moreexpensive ... the cho ice is strictlyup to you.

" For waterproofing those out­door connection.. and connectors.1' \ 'C had very good luck ..... ith aproduct called Ptasr-Dip w . It's afast-curing liquid plastic materialthat's intended primarily for coat­ing tool hand.les. A can ofthe thickliquid costs about 57 at Ilome De­pot™ and other hardware and ho.lffiCcenters, oot it should last you a goodlong while. I usually pot two coatsof it on all of my outdoor connec­tions. Fo r wire conoccr«m!'>, such 30\

separating a coax shield and centerconductor for feeding a dipole an­tcnna. I immobilize the point wherethe shield and center conductorseparate. using hot glue (hot glueguns are great fo r lots of things ).Then I attach solder lugs to the endsof the shield and center conduc­tor-where attachment to the an­tcnna will take place. Finally, I dipthe entire end (including the solderlugs) into the Pla-t-Dip and let itcure. Aft er curing, [ US" a sharphobby knife to trim off the excessPlast-Dip insulation that covcrs theends of the solder lugs. Neal, easyand veT)" waterproof! "

Moda l/lor :5l1ote: Good suxxes·[iOIlS, Phil. lVaterprlwfinRomdoorcoux fi ,tillg5 CUll't be l!l"er.urelled ;allY moi.ullre in el'ell the solill in­sula/ion coax is di,fmtrmH. Thel'hield ofa {"(XL{ mll.\1(Ip/Jear as a.n/lid l."CHldllctor to RF: thll/ is, e(II'hmer/appillg slrand of braid mllsttouch os many of i15 neighborillXSlTlUrd.f (6" possible, seeminx w be (.I.w1id oltter pipe, It /Iter (flUl)" son in­side /lle("tXLfjuete/ .5pOils this shield·illR I[lKllit)" (and)"011can ~ le/l itby DC"Sis/lUree ched:.s alotU>-;t "'.It~t bete.fled ~ilh true RF lesting, looting

for lo.H or 1eaki..IgeJ.Eren a 117ltui llicAin IhRO/./ll. foor cable s jacker must bere-sealed .Phi/ s s/lggestiofH 011 thebest (loon 'sf loSJ} ('able are olsoII ell raken . El"en if)"our l'ntirect.lhlem n can i be of a 101l"-loss mrielY.

From P hil S~la.. ADSX: " I' dsuggest that you con..ider using991 3 coax cahle, instead o f themore popular RG-2 l 3, for yourVIIF/UHF antenna feedlines. 9913ha..ahoul a third less loss th,U1 RG­213 at a gi"en frequency, and ismuch easier to 'con ncctflTi :te' withthe Mandatd PL-259 L'HF connec­tors. l1lc inner insulation is ea... ier10 llirip sinL-e it is mostly air! Theshield is ea.... ier to solder 10 the PL·259 since the in ner d ieleclricdllCsn' t conduci the heat away as itdoes in the RG-2 13 t)'IlC o f cahle!>.Cable X-pens (orden 1-8CXl-828­33·m, lech inf. 1-847-520-3003)sells 99 13 for 42 cenlS per fOOl,whic h is o nly about s ix ce nlSper 1'00 more than RG-21 3. The

Cons iderable cableconsiderations

he eas ily cut with a handsaw, orsimply scored with a utility knife,then cracked over the sharp edgeof a tahle-the ragged edge canthen he either tiled or lightly 'fi re­polished' with a propane torch (goeasy, it dllC !'>n't take much heat).

" The white Plexiglas is then the'perfect ' writing surface for eitherdry marke r pens o r the w atersoluble pens sold in art store.. andomce ..upply outlets. I prefer the'dry markers' myself, 0llC of .....hichis the Expo Markaway 3™ , :-':0.83000, by' Sanford. Black is prob­ably the best color and a chisel­..baped lip works nil-ely for me.

"C leaning the while Plexiglassurface after usc i-. ea...)' tOO, A dryerase spray cleaner is sold specifi ­cally for this purpo-.e, but 1' \'C

found that lacquer thinner. pouredinto a defunct grass window cleanersptay bottle, works jU!'>1 as well andat a fraction of the cosr. The lac­quer thinner dcesn'I seem to ;lUackor soften the while Plexiglas thatI'm using in any way,"

Moderator 's "OIl': tve used asimilar idea in Ill)' oll"n ham .~h(l(-k

lu inX (/ "note j ouer." consisting ofa washable penand plastic-coatedtablet , made f or wall hunging neara kitchentelephone , III this nul', 1.1

damp cloth witl erase everything ,Remembe r those lillIe marker ,11(1/(' .1with a d ear plastic Oil lop.followedby a translucent sheet and elidingwith n Mack 11'fl.\)' surface? Ytm .l' im­ply lifted /11/' tl1 'Otop sheets 10 erasethe whole tablet ... great[un /0 w ea.. I remember.

I

o

hum U~\' id Hym anK DOO:'lri.-: A way to cut down onpaper cos ts in your ham shack:" I've been able to drastically cutdownon the amount o f scratch pa­perthat I usc by assigning the note­taking task to a scrap piece of 1/4"thick. 8 1/2" x I I" chunk of whilePlexiglas" instead. Smooth whilePlexiglas is available from surplusoutlets around the country at veryreasonable prices ... often sold bythe pound (1ook in your YellowPages under 'surplu.H etail'). lt can

Not written in stone

one ortbose 'cloth-tape yardsticks:attached il to the antenna using a'twist-tic,' and now Iknow I' ll haveevery thing needed for adjusting theantenna. You can 'customize' thisbasic idea to fit your own antenna­clement needs,depending upon thepart icular model of adjustable•uucnna that you haw : '

..stoderaior s note: Good idea ,BiII:also ,doll )jcK8et to '·twilt-tie -­th(lf special Allen wrench or an in­expensive small screwdriver 10 the

IJtlcJ.:lI!?e if loosening and tighten­ing set-screws if involved in the ad­j ustment . A small, pla stic" zip -lock " bag wnn a ho lepunched into one comer can holdthese odds and ends. The bag ineljnit! then be secured to the antenna11(1d.:.aKe lI'ith a "twist-tie " or shortle/lxth ofrabte-tacing twine,

o 0

I.

HC-181U crystals

~ ~o0

)--1 : 0

l6-pin~DIP socket 0

0Fi lter ~ -'-capacitor I-

• , •

Adjustable antenna tip

From Willi am T h lm J r .I'Ii IQ\'Q : Bill has been \CI)' sup­portiv e. witha nurnbcrof glll.1lI tip:..-- Iown a portable umcnna that cov­ers several VIIF/UUF ham bands.bUI it must hi: physically adjustedfor each dillerent band. After los­ing the adju..rmc nt instruction sonce. I decided not to let th:u hap­pen again, so I got the tuning in­srruction s from a fr iend . the ntransfe rred them to the antenna'sbase using a customizahlc rubberstamp kit like the ones !'>o ld in manyoffice supply stores. Aco.uofclcarlacquer spray ove r the stam pingsealed it. 'Iomak c sure that l alwayshad a tap..' measure with the antennafor lhose critical ad justments, Imad" a lrip to lhe XYL's hworitesewing supply !'>lore and purchased

With the first issue of the newyear comes a nice variety of "HamTo Ilam"tip!'>. \Iany thanks- to thosewho' ve taken the t in~ to send intheir idea.. (often several) during1996, as well ;l'" to the names thaiweOre seeing for lhe first time. I'malway's looking for more ups. ideas,suggestions and ...boncut.. to keepthe column going and growing, -.0

please don ' t hesitate. The addr'c:s......is above.

FIg , I. K847f £ /W.JU D S ult'll0{1I0,," a foar-crystal kidderfilter might belaid Ollt /lsinX I I stl/lltkml16-I,in DIP Ie .ff J(·tet for IIItJ.lUlting the cr)"stllis.

54 73 Amateur Radio Today • Janua ry 1997

Dave Miller NZ9E7462 Lawler AvenueNiles IL6071 4-31 08

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SEE THE SPACE SHU~:JIDEOAND GET THE ATV BUGMany ATV repeate rs and individuals are rettansmitting SpaceShuttle Video & Audio from their TVRO's tuned to Spacenet 2transponder 9 or weather radar during significant storms, as wellas home camcorder video lrom other hams. If irs being done inyour area on 420· check page 538 In the 95-96 ARRL Repeate rDirectory or call us, ATV repeate rs are springing up allover - allyou need is one of the TVC-4G ATV 420-4SO MHz downconveters.add any TV set to ch 2. 3 or 4 and a 70 CM antenna (you can useyour 435 Oscar antenna). You dont need computers or otherradios , lrs that easy. We also have ATV cownconverters. anten­nas. transmitters and amplifi ers lor the 400, 900 and 1200 MHz

bands. In fact we are your one stop for allyour ATV needs and info.We ship most items with in 24 hours alter you call.Hams , call for our complete 10 page ATV catalogue.

1. Frank Brumbaugh KB4ZGC1W4UD

c/o DcfcndlniP.O. Box 30Salinas PR 00751

David L Hyman KB00NF1455 Edgcumbe RoadS1. Paul MN 55116

So why are cesspools like thatpoisoning our hobby? It seemsto me this is largely the result ofa lack of credible leadershipfrom our one (and really only)national organization. The pa­thetie weakness of our ARRLleadership has left amateur radioin a similar situation to a leader­less country like Somalia. Thisweakness starts right at the top:the ARRL board of directors.which you continue to re-elect .My bumper sticker Never Re­elect Anyone (the NRA for the'90s) should be not just appliedto Congress, to help flush out

Continued on page 56

Phil Salas AD5X1517 Creekside DriveRichardson TX 75081

Note: The ideas and sugges­tions contributed to this columnby its readers have not necessar­ily been tested by the column'smoderator nor by the staff of 73magazine, and thus no guaranteeof operational success is implied.Always use your own best judg­ment before modifying any elec­tronic item fro m the originalequipment manufac turer 's speci­ficat ions . No responsibili ty isimplied by the moderator or 73magaz ine for any equ ipmentdamage or malfunction resultingfrom information supplied in thiscolumn.

Please send all correspondencere la ting to this column to 73magazine's "Ham To Ham" col­umn , clo Da ve Miller NZ9E,7462 Lawler Avenue, Niles, IL60714-3 108, USA. All contribu­tions used in this column will bereimbursed by a contributor' s fccof SID, which includes its exclu­sive use by 73 magazine. We willauempt to respond to all legiti­mate contributo rs' ideas in atimely manner, but be sure to sendall specifi c questions on anyparticular tip to the originator ofthe idea, not to th is column'smoderator nor to 73. fa

NCUER SR¥ OICConltnuedJrom page 33

in with catcalls, carriers, andjamming, but without signingcalls,

If I were an advisor for anycompany wanting to get the useof a ham band for their products,I'd record and edit a few days ofthis kind of crapola as proof thatthere dearly are much betterpublic uses for the billions ofdollars worth of ham spectrumwe've inherited and are laying towaste. Since we claim to be self­regulating, we have no valid ex­cusc for allowing this kind ofsickness 10 go on.

From J, Frank BrumbaughKB-IZGC/W4UD: "When con­structing crystal ladder IF filters,you can save PC board space, sim­plify the layout time and make thecrystals much easier to check orreplace by simply using a standardl6-pin DIP socket to hold the fourcrystals needed. Interestingly, theHC-I8IU style of crystal with wireleads will plug in directly acrossthree pins of a standard DIP ICsocket. A quick look. at folg, 1 willillustrate how a four-crystal filterwould be wired using this scheme.Just clip the HC-1 8IU's leads toabout 114~, then plug in the crys­tals after all of the heat-producingsoldering has been done. If youneed more than four crystals, justadd another DIP socket!"

Moderator's note: Clever idea,Fronk .By the WlI)', Frank 's right ,awire-lead HC-18lU fits perjectlyacross three pins oja normal DIPsocket. I'd recommend using thebest DIPsockets you can affordforthis application . TM ones withround "machined" pins hold theCT)'SloJ nice and righl/y.

Murphy' s Corolla ry: Whenworking out a problem on a spe­cific piece of equipment, try sleep­ing on it... it' s sure to make animpression!

Many thanks to this month'scon­tributors. Without your continuedinput, I'd soon run out of ideas .Please keep them coming.

William Thim. Jr. N IQVQ50 Miller RoadBroad Brook cr 06016-9676

Crystal DIP

everyf oot that you can manage willbe ,hat much beuer.

CIRClE 1Q ON REAOER SERVICE C4IlD

WANT TO LEARN CODE?

think they are important.But they also tend to want to

hide their faces. I went to acostume party when I was a kid.My mother made a Shadow cos­tume for me, complete with ablack vei l. That was the firsttime I'd ever been at a partywhere my face was hidden . andwow. did that feel different. Sud­denly I was very outgoing andthe life o f the part y. A vei l ormask gives one a sense o f secu­rity. And so does a beard 10 hidebehi nd. Think over the beardedpeople you know and see if youthi nk I' m right.

The onl y bearded guy I canthi nk of that this doesn't fit wasSam Harris W8UKSIW1F7J1W lB U, bUI then hc wore his inthe '40s and ' 50s, back whenthat was an outrageous thing todo-which was why he did u.lie didn't j ust wear it , heflaunted it.

vegettzteg

Unless you've chosen 10 beuneducated in the food depart­ment (aka ignorant). you knowthat you re all y should be includ­ing a hefty bunch of veggies toyou r diet. At least if you want tomake it with any grace throughyour 50s and nOI join the stric tlysteak and potatoes group in theirS2.()()()..a-day hospita l wards.Yes, I know, you and Bush arenot broccoli fans. I happen 10like it, but I can almost empa­thize with those who don' t.When I was a kid I hated cauli­flowe r and didn't think I' d everlike it. Now I love il.

Anyway. I' ve found a greatway to not j ust make theseveggies delicious. but to do it inthei r healthiest (for you) form:raw. Here 's the deal. I hope youhave a blender. I throw in a cupeach of raw broccoli and cauli­flower. and a half cup o f raw car­rots. Zizz 'em together untilthey're in pieces sli ghtly smallerthan Grape Nuts.

You 're goi ng to need somesalad dressing for this. I'm usinga couple of tablespoons o f myold coles law recipe. It has twopart s extra virgi n ol ive oil, twopans ap ple cider vinegar. onepart honey, one part mayonna ise.six part s plain yogurt, a teaspoonor two of ce lery seeds, salt andpepper to tas te . Then whip it alltogether. This makes a fabu loussweet-sour dressin g that 's greatfor slaw and as a veggle dip. It'sreasonably low cal and easy to

Ccnrtnued on page 59

Have you ever noticed howmany professors wear beards?Maybe there 's a good psycbologl­C".t.I reason for this. Try on myreasoning and see how it fits.

what has teaching college gOIgoing for it? Short hours. lOIS ofpre stige, tenure (you ca n' t gelfired), paid sabbaticals , and gen­erous retirement be nefi ts. No,you' ll rever make a lot of money,but the security is a trade-off.And the prestige. They sure playthai g ame . Doctor. Profe sso r.Distinguished Professor.

Now. if you were a person withlow self-esteem. also known as aninferiority complex, you wouldtcnd to look for work where pres­tige is flaunted. Low self-esteempeople can't help but do every­thing they can to make others

value and are these days con trib­uting little in return . All you gelis co mplaims-about interfer­ence , bad language, repeater co­ord ination, and so on. Try silti ngin a commissioner's chai r for aminute and see how that fee ls.

If you feel that I'm du mpingon the ARRL about all this. thenplease let me know who you rec­ommend to help sol ve ou r prob­lems? If you really don't be lieveour leaders have no responsi­bility to lead. then what enema­uvedo you suggest? If you don' thave an answer, ask your direc­lor and then let me know what heproposes.

Or should I start work on a book,lIam Radio - In Memoriam?

Professors and Beards

Bob Beck TalksBob explains how he devetoped the blood purifier circuit,

the lengths the Alben Einstein College of Medicine hospital,which discovered and then patented the process, has gone 10 tokeep it secret, its success in treating AIDS and any other virus,fungus. yeast. parasite or mil-rube in the blood. 1-1" talks aboutcolloidal silver, and the unexpected side effects of the bloodpurifier and magnetic pulse unit in weight reduction and re­growing II'IlI le pailI'm baldness hai r. This is one heck of a talk.

Order BR $10

Pbooe 800-274-717l Of 6l)l·92H1OSB. FAX 6Ol-924·1l61 l . Of see ..-..k.'f r......011 pqe 88 for llfdfnn, int........l.....

Wayne 's Submarine Adventures in WWIIThese srories w~ooginal ly~ in the Dnun Nr-o'sk lt"

10~ crew memb..'n10 OOI"D:' 10 the yearly Drvm mu1iln>in ~1obi1e, whm- the Drum ison display in Battleship Park. nexl10 the Alnhoma. If you \lsit the Drum )'OU'U see many of theo.etr\O,~ko:CfS on d"play. Submarine life was boring most of thetime. but suddrnly there was inu=e llI;Iion. You'U read about thetimes wecame very close 10 being Slri;. - and acouple times w~I saved the boat from disas1Cr. You'Ualso read lIw.: inside Wlfy onthe Amelia F.athart spymi~ Says Jim Walter W9AW, "Ijustn:-read your sub alh-mllreS in WWll _ great Sluff - enjoyedevery page!"

OrderSA. S8

by. The only hope I can see forour survival is as a way to helpget kids interested in high-techcareers. the way we did beforethe ARRL virtually sloppedyoungsters from entering thehobby 33 years ago. We haw toprovide some SOil o f visiblepubl ic service if we're going tohold our ham bands. which arewort h tens to hundreds of bil­lion s today. But without leader­ship lr 's o nly a matte r of lime.and I doubt thai we have muchof that.

But how about the FCC­wo n' , t he y protect us? Whyshould they? These days we arenoth ing bUI a royal pain in thebutt and an additional difficul t­to-j ustify expense for an Quintwhose budget is being cut back,year after year. Instead of put­ting the pressure on the ARRL 10so lve our problems we write tothe FCC. demanding help. Whennothing comes of that we writeto ou r Senator or Congressman,as king him to put pressure o nthe FCC to help. And he thensends a copy to the FCC. push­ing for action. And since there islillie the FCC can do. they j ustwant to stop the pain.

What would you do if youwere a politicall y appointedFCC commissioner? You knowlill ie about the history of ama­teu r radio. All you know is thatthere is a di sorganized bunch o fold (very old and largely lowermiddle class) white men who aree njoy ing billio ns o f dollarsworth of the spectrum whichthey inherited when it was of no

,hail. h1.. Ih", d.al<r;. Ih• .-\ RIl I .•'" ....nd ~~,~~

• '-! S.... H Ie\ ~id.n" add ,L12 ,a , ) I,,,(,! ,1 l. !'.O. flo" ~.IIl~, fl.p!. \, ~. ' ."P"" 1It';l<'h.

C \ nllS~ .\.,.... ir~ ~ /. ", ~ /, inch di,l .

that mess, but also to your ARRLboard of director rubber-stampvoting eve ry other year. Keepflushing until we get some youngpeople in there and see signs ofleadership beginning to show.

How will you know? Whenyou see signs that the League isatt acking messes like 14,313,K I MAN's endless ego gratifica­tion , the lack of youngsters com­ing into the hobby, our overalllack of growth <except for no­coders), the disinterest of the no­coders in upgrading , and stufflike that.

Amateur rad io got grandfa­thcrcd into most of our presentham bands as a result of the pio­neering work hams did in the earl i­est days of radio. Then we held onto most o f our bands by providingclearly visible public services.Amateur rad io was often the onlymeans of communicat ing in emer­gencies. And. as I keep mention­ing. 80% of the licensed hamswent into the military for W'VII.providing a priceless contributionto ou r winning the war. in whichradio. rad ar and so nar werecritically imponant.

But today. due to an almost to­tal lack of leadership, we are nolonger the pioneering group weonce were. We no longe r arc o fany value whatever to the mili­tary in C3-~e of a war. Even ourvaunted emerge ncy co mmun ica­tions arc disorgan ized and beingmade irrelevant as other commu­nications serv ices arc passing us

NEUER SRY DIECon Unuedftvm page 55

Morse Tutor Gold from G.G.T.E. is theanswer for beginners and experts alike.

"Gd tbe software the ARRLsellsand usestocreatcpractice and testtapes; and ~Iorsr Tulor (;Old isapproved for VE exams al all levels,

0S-C 1911I7.Gl.oIE "-l'ododnearly 20.000"""'"on4 proo.p«ttw"-no -...llho .....nd lIw<Jo¢ pr<WaO 5llu<turcd '"-'no on4 •~. ofclwto<Ia", "'Cfd on4 _ &-.. SlJ-.hl r.-vdlIICnIII mol;e dv pmoeu Nmpk W fun."ThIo pop_n fe.l\ll.. ...y ....t opeedj.. odf~. ..........chonder dnIIo Mlb dv •........".. }"OII sde<1:, and rou <an ."..,,'"ywrOflll dnIb or IllIplI1la1lib You <an 1)......1»1 )"OU '-Of

c:opy by hond and .... tbc ,...w """ Iinot . 1• _ ~l !heFanlSlOICIfth or ~..otondoId ltk:lhod, o&d tbc Ion< U<qII<n<.l' "",,"Icomfortahlt for}"OII or odoecl your<:ode.peedin lendlS ofa word permlnu'e. For.u oos comp'''''' , ."" are toI...~.. Incommond

('C l1 inrdbv ~lo...~1 u,....GeI,1u<eo )'0"' Inl~m;d . pe.oler

~or",'uoooo..d.And, if""" Ii.'e ..o""d board

({ M..... Tu''''' CoM ' "I'J'Olf> volume"""",01

IS o u'; d &ttmd 1lI,,,I.r and ,h. S", ulcl BI.,te' COll1 l" lLh~1tyf-'"","",,-~l .<>110 ar. lrad.""rk< of C.."ti,. T«hnok v Ltd

56 73 Amateur Radio Today - J anua ry 1997

HOMING IN

Joe Moell P-E. KOOVPO Box 2508Fullerton. CA 92637

A Foxhunting Jamboree

When did you first hear 300ulradio d irect ion find ing (RDF)?Since it has beco me a too l forfi ndin g downed aircraft and sto­le n ca rs. tocay's sc hool k id sprobably get a vague notio n o f itearly on. Sadly. they aren ' t toldthai it l'an also be great fun forthem.

A recent E-mail exchange withTom Stewart K3TS brought backmemories o f my introduct ion toROE Tom wrote a classic art icleabout 2 meter hidden transmitterhunting in New JeTS!." )' for theSeptember 1957 issue of QST. Iwas 10 years old at the time andstudy ing for my ham ticket , fa ith­fully try ing 10 copy WI AW codepract ice e very night o n my drift)'Hallicraftcrs 5-38D receiver. ThatQST issue was one of my firstham radio magazines. Tom's taleso f T-hum trickery gOI me eager10 try the sport .

When my Novice license ar­rived the follo ...... ing spring, I agi­tared al the radio c lub in our to ...... nof I I,()()() souls to gel the grouptll hold some hidden transm itte rhunt s. Even though Novices had2 meie r phone privileges at thelime, ......e were a hundred milesfrom the nearest 2 meter act ivityand there were no re pea ters to

bridge the gap.Finally, the dub sched uled a

hum on 75 meter A\1. ...... here mostmobile c pcrari ng w as don e inthose days. I someho w managed10 lash together a two-tube 75mete r conve rte r ...... it h vibratorpo wer supply and connect it 10 thebroadcast receiver in the family 's

ga s-g uzz ler conv ertib le . O fcourse I had to talk Dad into driv­ing, Bemused by the w hole thing,he agreed.

For an RDF antenna. I used themulti-tum flat loop from the backcove r of a n old table modelbroadcast set . I hadn't lea rnedenough RF theory to do a goodjob of reso nat ing and coupli ng it ,so it wasn' t ve ry sensit ive or di­rect iona l. Dad and I did a lo t of

NumbM 57 0 11 your F~blJd I; lJrd

Radio Direction Finding

riding around just try ing 10 heara signal o ver the ignit ion noise.Fortunately. the hunt boundarieswere small and gas was cheap,

Hu ndreds of Tth unrs late r, I stillthink it is the mo st fun yo u canhave ill ha m radio. I wish everyyoungster could experience it. Butho w ma ny kids no wadays havesupporncc radio clubs and paticrufathers to Elmer them into it'.' 1I0wcan we bring kids and RD F 10­gether? I think "Horning In" read­ers Greg and Gabriella Ow ens(WA6I1 KM and KE6JQS ) han:'found an answer,

Th is c a mpgroundwelcomes foxes

G reg and Gabriella ' s letter ar­rived short ly aftc r Labo r Day.They were in charge o fa commit ­tee Ir om the Simi Set tlers Rad ioClu b thaI woul d be hosung aS eoul Ja mboree -o n-the - Ai r(JOTA ) campout. They ...... anted toknow how to put on a demonstra­lion o f foxhunt ing (also calledradio-orienteering and A Rm ·) aspan o f their JOTA acuvmcs. Whatan opportunny!

JO TA is a worl dwi de ha mevent, held annu ally ill mid-Oc­tobcr for almost 40 ye ars, Hav­ing never been in Scouts , I kne wvery lillie about it . I had no ideaif fo xhu nting had ever been donethere before. (Actually, I' m stillnOI sure.) Either way, I knew thaith is opportun ity couldn't hepa s sed up, so J ca lled themimmediately.

JOTA celebrations run for a 48­hour period beginning Friday af­ternoon. They range fro m simpleto elahomte. In so me tow ns , aham in vite s a troop or two for aham shac k visit. letting Scoutsparticipate in contacts wi th o therJOTA groups , In other places , it 'sa full -h low n Ca m poree wit h

m an y s tations and activiue s.Tha t ' s what the Settle rs we replanning.

" We hope to have stations one" ery al'liv'e HF and VHr band,"Gabrie lla told me. " We ' ll demon ­stra te hOlh Hlice and C W modeson the a ir, Local ATVers w ill se tup IWO stations so the SCOUIScan

Photo It, April WAflOPS helped 1.').1'/ 11 ;11 RVF /0 eager .\'('OU/S heforethey In'lIt Ollt 10 hum, Looking 011 i ,1 longt ime Sall/tillX supporter

Darryl Wit/mill! KF6V I, (Pho hy Jm' Aloell K()O V. }

have televis ion QSOs back and each in sequence, just like they doforth . We will al so haw code os- ill a formal imemalional-rulCl> com-cillator kits for them to solder petition (see "Homing In" for Au -together." gust and September 1996).

The Simi Sett lers ' JOTA si te Greg surveyed to pographica lwould be Lake C asi tas Ren e - maps of the site and suggested aarion Area near scenic Ojai. C ali - hilly area of about one square milefomia. Scouts fro m Ventura. Lo s across IOe pa rk mad rrorn the camp-Angeles and Santa Burbara coun- ing area He even agreed 10 maketics we re invited, Several hun - lots of copies of that map for thed rcd co uld he accommodated . Scouts, " Don' t worry," he to ld me,T he event would offic ial ly begi n "they are prepared for being in theat noon Saturday and continue for woods and will bring compasses2-1 hours , Many Scout s would with the m."Good, all lwouldnecdcamp over Saturday night, whil e for orienteering would he a batchothers would be at the lake sho re of protractors.for just a few hours on one day, For a week before lhe event. IFoxhunt ing at night would be spent each evening tun ing up myun safe, so we had to make it pos- RDF sets and borrowing more. Ons iblc for many Scouts to hunt at Friday afternoon. April and Jwe ntthe same time during our limit ed 10 the sill.' to cbcx-k il out. I quicklyavailable ho urs . realized that my imagination had

Lake Casitas is a drive of over not served me well, The hilly area100 m iles fo r 'l-hutue rs in my was Icnced off. Noncccss ! Oh well,a rea , bu t il is only about 40 m iles it wasn't very shady. In trut h, itfrom Santa Barbara, where there looked like a harrell home for rattle-is a grow ing group o f rad io - snakes. Besides. it was too far awayo rienteering enth usi asts. I own from the campsite ,plenty offox transmitters. hut not We decided 10 hid e the foxesenough RDF gear for dozens o f within the la rge wooded JOTAScours to use, What 's more, April campground, IX)( far from our v-anand I would need knowledgeable ...... here we were sho wing a viocc o fhelpers for one-on-one tra ining internat ional radio-orienteeringof the Scours. I li pped off E-mai l l. Jmpetitions(see l.bolo A). Scoutsto Marvin Johnston KE6HTS of would not have a long hike. Wethe Santa Barbara Amateur Ra- could easily watch and help. As adio Club and he im media te ly side be nef it , the sight of the magreed to hel p. combing the grounds with sniffing

Having no ex per ience w ith gear would attract much more at-fox hunting de monstrations for tcnnon to our demonstration.pre-tee ns. I could o nly try 10 en- The IWO hundred or so Scoutsvision how tt would go. I imago that came to Lake Casitas wereined tha t we would take th e mo stly in el ementary sc hoo l.Scouts in packs or troops of a They may be champs at the latestdozen o r tw o and give the m a video games, hut they had to startquick show- and- te ll o n RD Fing at sq uare one wh en il ca me 10and map plolling. Then we wou ld RDE 1'\0 way l'Ould we simplyhand OUI so me gear and send them slap gear into lhe ir hands and sendinto the wlxxls to Iry to find five Ihem oul. It workcd hestto guidefoxes Iransmitt ing for a minute them along in groups of Iwo or

73 Amateur Radio Today · January 1997 57

the fox batteries fo r more hunts

the ne xt day.

lf there was any doubt that

foxhunring enthralled the Scouts.it was dispelled Sunday mo rn ing .

As we pulled in to the camp­

ground. we were greeted with

young voices shouting, 'The foxpeople arc here!" Before we could

ge t the R D F gear out , were

mobbed. Scouts who had hunted

on Saturday wanted to try again.because the faxes were all in new

locution s. We gave firs t prio rity10 tho se who had not gotten achance 10 hunt Saturday: then welet the res t have a t it again.

Hats off to the Simi Settlers Ra­

d io Club for going beyond the callor d uty in provid ing a special

JOTA experience for the Scouts.Special ku dos to Greg and

Gahrie lla for paving the way forA R DF eve nts , Also tha nk s 10

foxhunt ing enthusiasts from the

S anta Barbara Amate ur RadioCluh fo r hel p ing . In addition toM arv in , they were Ste phenNelso n KD 6 V E X . NercllaReginaro. Reg Reginato KE6ZQY,Br ian Pedd icord Kf6DZK, Mike

Peddico rd KEfi OTM . Scott

Ph ill ip s KF6EDD . H ube rtStamps KC()!\AH , Bib Ummels

KE6WYA. and Pres ide nt Da rry lWidman Kf 6Dl.

Many Scour officials at JOTA-%

expressed interest in future foxhumingdemos and activities for their dens,

troops, and packs. G iven crongh in­expensive equipment and trained

leade rship, radio-orienteering L"t.1lI1d11<-'(."(nne a mainstream Scouting activ­

ity. I have lots of ideas for gear. But

will Scoutingorganizations aLTOSS the

country heable to find crxughThurn­crs to get this program o11" thc ground?

fox. T he ir a rm s wo uld beco mefa tigued in ahou t three minutes

and the beam wou ld sli p down to

shoulder he ight (sec Photo C). O fcourse that adversely a ffected the

bea m's sensitivity a nd direc tivity.

In th e fu ture , I wa nt to ha ve

lighter a ntennas with masts, so

the y can easily be held o ve rhead.

Competit ive foxhu rucrs preferus ing ea rp hones 10 he ar fo x

modulation a nd strength tones in

noi sy surroundings. That 's whymost fo reign-made integ rated re­

ce iver/antennas don 't have speak­

ers. But phones aren' t ideal furone-on-one train ing. M y solution

was to ha ve the trainee wear the m

around the neck instead o f overthe ears. With gain turned up, they

put o ut eno ugh audio for t hetrai ner, the trainee, and observersto hear. As a bonus. th is el im i­

nated the chance of an a udio blast

d irectly in to the cars if the RFgain control was imprope rly set

when the fox came o n the air.

ARDF and kit bu ild ing we re

smash hi ts at o ur JOTA operation.Lots o f Scouts were beeping awayo n the ir newly-built code oscilla­

to rs as they came u p to th efoxhunttng d isplay (see Photo D ).S o me o lder Scouts said they'd

had lots o f HF QSOs in previousyears, so they we re g lad to have

some ne.... act ivi tie s this time.

Most Scouts had an opportu­

nit y to track at leas t o ne fox

Sat urday afternoon. Darkness fe llaround 6 p.m . and it was t ime for

a big spag hett i dinner around thecampfire. T hen we le ft them ror

the night. promising to charge up

More "fox people" needed

Photo D, Who says Morse is dead? Another hit ofJOTA-96 \\'l/,V thiscode oscillator kit project, (Photo hv April "Joel! WA60/'S .)

Better tools needed

othe r was the cle verl y ca mou­

tlaged "stud T' (see " Homing In"

for October 1996). That one al­ways got looks of amazeme nt

when the Scouts flu shed it OUI. As

time a nd equipment permitted,those who did well on co nt inuous

foxes could try to hag the in ter­

mittcnt ones on 146.565 MHz.

To regular users o f VHF-FM,

irs easy 10 ga uge the strength ofincom ing sig nal s by the amount

o f background hiss, o r lack o f it

(q uieting). But 10 a C ob S co utwho has ne ve r hel d a hand ie ­talkie befo re , it's no t obv ious.A rter some prac tice , a fe w of

them did well at getting hearings

with an HT, beam and ac tive at­rcnuator. Others couldn' t seem to

get the hang of it. especially if the

HT didn 't ha ve an S-meter.

O ther types of RDF sets were

much easier for kids to learn. T heSanta Barhara group brought sev­

eral d ual -d ipo le homing se ts(TDGA type) with le ft-right indi­cat ion (mete r or LEDs). Although

TOOA s are more p ron e to

mulr ipath bearing errors and theylack s ignal strength ind icatio n, thek ids found the m easy to learn andhad good results (see Photo 8 ).

ln Europe and Asia, whe re ra­dio-orienteering is a popular sport

in schools, everyone uses s pec ial

a mpl itude-based RDF sets for 2met ers . T he re are ma ny varia ­

tions, but they a ll incorpo rate ayagi or phased a rray antenna anda built-i n recei ver w ith

w ide - range RF ga in con trol.

Signal strength is indicated by apanel me ter, tone pit ch. o r tone

loud ness.I had only two of these fore ign­

made sets along, but I think they

were easiest for Scouts to lea rnto use . All they had to do was turn

the antenna fo r strongest sig nalindication and walk tha t wa y.

Their exci tement grew as signals t ren gth rose and the y had tolo wer the RF gain; it meant they

were dos ing in . Bea rings werenearly alwa ys accurate .

Weight was the biggest disad-Photo C. 7() this Cut: SCOIlI, RDF vantage of the integrated rece iver/

gear seems a hit heavv after a few antennas. It surprised me how dif-minutes offox tracking. Next lime, ficult it was fo r so me grade-

I'll adda mast ,W this Russian-made schoolers to hold a th ree-e lement

set Hili he hl'll! high morl' easilv. 2 me te r yug i o ve rhe ad lo ng

(PhotobvJee Moe/! K(>OV) e nough to hunt down a hidden

58 73 Amateur Radio Today • January 1997

three as the y learned. One Scoutat a time used the RDF set while

the others watched . It wo uld the n

be thei r turn to find the next foxes .

Five cycl ing intermittent trans­

mitters proved to he too con fus­ing during the learning process.

'oNe changed two o f the m to be

cont inuous crmucrs on se paratefrequencies below 146 MHz,just

for first-ti mers. O ne was in a su r­

p lus amm un itio n box whi le the

Photo H. Reg Rt'gi/MIIO KE6ZQY ofSan/a Barbara shows (/Scout how touse his dual-dipole 1UOA RDF set

ill the JOTA-% C11I1/PXrrlUIII!. (PhO/oby April Mod! WAoOPS';

VHF and Above Operation

Number 59 on roor Feedbilcll c.rd

ROOUE & BEYONDArc you " Ho ming ln" readers

wi ll ing to bu ild a nd stockpilesome kid-proof ARDF gear. seekOUi your local Scour leaders, and

put on traini ng sessions? I wantto hear construc tive o pinions a nd

ideas from both Tvnunrcr s and

Scout leaders about th is concept.Le t's prove that we mean il whe nwe say we wa nt mo re young

peo ple invo lved in ha m radio ac­ti vitic s . Se nd E- m a i l to

Hornmginw aot.com o r write to

the address at the beg inning o f

th is column. m

NEUER SRY DIECcnrtnued from porI(' 56

make, If ) '00 use a hal f cup mea­suring unit you"I l use one quartof yogurt a nd e nd up with a bouttwo q uarts o f dressing.

The olive o il is good for ) 'OU.

as a rc the apple cider vinegar.hone y. a nd yogurt . The best partis that th is he lps yo u li ve lo nge rso you can watc h whi le yo ur e n­e m ies d ie of hea n attacks. can­cet, and o the r eat ing diseases .lI e h. he h.

The combo of the raw zizzcdveggtes and slaw dressi ng makeseating health food easy. He y.give it a try. It might he lp keepyou from becom ing a vcggie.

C. l. Ho ughton WB6IGPSan Diego Mic rowave Group6345 Badger Lake AveSan Die go CA 92 119c1hough @aol .com

A 1296 MHz Amplifier/Mixer for Converter Use

With the co ming of the ne w year

and the holidays behind U\ , it '\ lime

10 stan ge ll ing our microwave andother pnljl.'l1.S off the back burnera nd start purring Ihe m together.Winter affects us in varying way's.

with our many states and thei r

vastly different geographical set­tmgs. f or tl~ here o n the west Coast

it means purring o n a heavy shin or

light jacket for the c hilly mornings.or getting prepared for o ur rai ny

season.For other parts o f the country

with much harsher ....'cat hcr condi­

nou-, th is is tru ly the ti me fo r

e vening workbench projec ts . Lastmo nth we covered several older 2meier multi mode rigs , showing

their use in SSB and narrowbandF\-t operation as a lo wer-frequl"nC)'

IF system, This If system is the

heart of this RFconverter. reedingonly a mixer. ti ller and local oSl,-il­l. uor as add itions fo r constructio n

of a 12% Mil l con verter.

Construction

This rig: was quite easy to con­

struct. While it i ~ a pea nut whistle(low power: + IOdBm), n is a com­

plete rig. needing only a loca l oscil­lator for oper at ion. Tbc beauty ofthi s approach was that al l the am­

plifiers arc p;.U1 of existing circu itrythilt is readi ly available. This c ir­

cui try requircv only assembly into

a shielded OOX to house the mixer.

a mpl ifier PC boa rds a nd re la y

switc hing circ uitry.This project was started ....'hen I

tried to pu t toge ther PC boar ds us­

ing ~IMIC am plifiers like the l\I ARseries. This mcant thru l would ha ve­

to come up with a PC board layout

and select a mpl ifiers to perform the

receive and transmit functions of alow power RFcontroller; It was also

intended to drive the transverterwith a 2 meter multimode rig a__ the

IF syste m in this project.

After several curs at breadboard­

ing Ihis project I discov ered that I

did nul need to construct amplifierc hai ns as they were already at hand.

T he a mplj fier v eamc from

Quulcomm surplus IF amplifier PCboanl\ that I had available. Tbcv

were o riginal ly a receiv e IF ampli­fier a nd a trans mit IF amplifier us­

ing multistage MMIC amplifiers.T hei r small sill". high ga in and out ­put power capability ( + I0 da rn o n

trunsrnit] made them a ve ry goodcandidate.The fi rst breadboard rescircuit was buih using these IF PCboards. wuh a fe-w other parts tossed

in. Tbese we re vimple RF relays,swuchmg a mixer fur convertingfreq uency and a simple power sup­ply regulato r. Having a111hc mate­

rial at hand and in modest q uant ity,

allowing for others to U\C it. made

this approach a natura l for repeat­

ability. Fi rst I had 10 construc t aworking mod el to prove thai mi ll­

iaturc inexpe nsi ve relays would

function at Il Yo 1\111/ . thus el imi­

nating expensive coaxial relays forlo w power swuchtng.

I wanted used smal l surplus min­iarure S POT re lays removed from

junk PC boanj-, 10 switch the OC

control voltages and the input andoutput RF switching: a' well. I was

hoping that the- RF losses would not

Gcvemmem Control

SMAIn/Out

CoaxOut

--"."

Re la y

B@

_-;::;"". Common

TX· SMA

RX ,/

--I

"C"

7810

' TX DC

RX DC

-I

RJ( BOARD

TXBOARD

' 10VDC

r:l----~~:;_-----;:;:t---:~=~:;: + 1 2vDC,. to switch from

RX to TX

RX

CoaxOut

Coax +10DCOut

"A"

SMA • TX

Com~""-.t.,;=-

SMAIn/Out

Fj~ . I . L(/yout , fiaXfall1 of Ihe amplifier ( 'O fll 'f'fl l'r Ullil .

T he rel ig io us fe rvor overabortion. pro a nd con. seems toha ve blinded both s ides to the re­alizat io n thut once they ge t thegovernme nt involved in relig ion.they have started o n the slipperyslope toward the governmentdominat ion and control o f re li­gion. I-> that real ly what the ywant '! The old camel's nose inthe tent sy ndrome?

The pro- lifers want to use thegovernment to fo rce the ir beliefso n e ve ryo ne. backed by our so­ca lled "correct io nal sy~tcm'"

T he prc-chotce rs want 10 forcetheir be liefs o n e veryone. viagovernme nt co ntrol. II" ei the rs ide wins. we allIosc .

T he sa me holds for sc hoolprayer, The damned j udgesshould ~ IOP try ing 10 get in­volvcd with rel ig io n vv. mego vernmcnt. Hec k. I sat th roughscbool prayers for years withoutbeing impacted one whit. II "' a so nt: of tho ",e ritual-> '" hich we didwi lhout th in king. like sa lutingthe n ag , which we lI ~eu 10 do

/e \'e ry day. You kno w. th.ll " O ne

COTlllTlued 01\ flage 8 /

73 Amate ur Radio Today· Ja nuary 1997 59

J J

+10 VDC45mA

J Preamp Gain25 to 30 dB

J; 800 MHz to 1000 MHz

IF Out

2SC4094

J

J;J;2SC40942SC4094

RF In

Fig . 2. Schemtltk d iagram II! the receive amplifier.

be excessive in these relays for I~ relay by mounling it directly at12% MHz. The only way 10 prove the coax connector location.this was to leave the theoretical en- what l have constructed is a rea-virc nmcur and actually build the sonablc layout that can be easilycircuit as originally proposed. reprod uced with the materials I will

The relays I selected were min- make available. However you arciaturc metal-enclosed '1'0 -5 relays free 10 experiment and change themanufactured by Teledyne. These layoul and application using therelays arc quite small and the exact same compo nents to suit your par-size of a modest power transistor ucular design requ irements. In this(Tf )- 5 me tal-cased power trans is- case the uld axiom applies: "Ifyoulor ). I did nOI try the small 12 mit change lhe recipe you mtghtchan gcrelil)'" ntfcred by Radio Shack (275- the product : ' Giv e it a 111' if you~-l l ) hut 1believe they should ....o rk like and watch forcirruit layoet aoJin a similar fashion. The thing that amplifier instabilities. Use similaris important arout using any dev ice PC board material of .062 double-at these frequenl,:ic!> i!> 10 make all !> kk.'d copper to shield ~'our circuitlead...as short as possjble. especiall y and connect the side plate with athe common ground leads. It is OK veum o f solder making a so lidto make the RF ampl ifier leads grou nded enclosure. I soldered thelonger. side plates 10 each other and the

I !>u£!!.eMmounting the relay up- bottom plate on the inside. connect-side down on a piece of copper cir- ing all copper foil surfaces togethercuit PC hoard blank. The entire ttl form a shield.copper Ioil of the PC hoard will Similarly a lop cover is also cutserv e as the ground shield and out of PC hoard rnatcnal to corn-mount for all components. I used pletc yom RF-tight enclosure. Seethe position 0 11 the side wall for the .·i~ . I for the dimensions of thecoax connector in/out SMA eon- enclosure thai I constructed. Di-nectar to he exactly at the pin of menstons do nul have to be strictlythe relay fo r the transfer contact . adhered to; just follow somethingThis gave minimum lead length to similar if you plan 10 use the IF

60 73 Amateur Radio Icaev » January 1997

amplifier boards that J will mak eavailable for this project.

T he IF ampli fiers that I usedwere surplus units remo ved fromQunlcomr n transceivers thai weconverted Lo 10 G lb operation.The specification on the receiveRF amplifier is about 2HIII 30 dBo f gain and 2 d B noi se figu remaking a very sensitive hig h gainRF front end. T he transmil IF. orin our case RF amplifier. has lessgain measuring 2-l d B hut il willprovide a higher po wer RF o ut­put of nearly + lO dBm. While th isis a peanut whisrle (12 mW) it isstill quire effective. Ex ternal switch­ing. and a poweramplifier will makethis converter a formidable 1296~1I1z transverter.

What I atte mpted 10 do i, 10pro vide ) O U with the bui ldingblocks o f c ircuitry to construc tthiv co nvener. T he thing thatmakes these amplifie rs au rncuvcis that they fit into this npplica­tionli kc a glove. Their smal l size( I " x 3"). high gain and ready toplace and play type o f circuitrymake them easy 10 use with + 12volt battery applications for horneor portable rigs.

As I staled earlier. I will providea mini kit of both the R:\ and TxPC boards with a 2lKJO Mil l. PCsurface mount mixer and a shortsect ion of waveguide to constructan evanescent mode fil ter (sec theend ofthis column for details). Theonly thing you will have to mid is alocal oscillator at 1152 MHz 10co mplete the transceiv er. ThaI j , ifyO(l also choose to usc a 144 ~1II 1

transceiver for your 1(-;" system. TheL a frequency would change if youchange the IF frequency you usc.If you used -l32 ~t Hl a.s the IF SyS­rem frequency then the La required

would be 86-l \ IH1..

Considering the 11 52 there arcseveral options o n the LO. includ­ing a % \1Hz crystal oscillator fol­lowed by a times-three multiplierand double to 576 "'1Il /~ followedby a single dou bler to 11 52 MH/..An alternative would be 10 phase­lock up an old CATV front end on11 52 MHt- for a very economicallocal oscillator. Ihave covered thesefur ATV projects and assume thatwith some modification the y couldadapt 10 this usc a, well. I used adifferent lac" with a synthesizer thatI had on hand,

This surplus synthesizer from

Qualcomm is in small quantityand not easily available at prese nt

in the model that wi ll gene rate

115 2 Mllz. \Ve do have modelsthat will lock up to 2304 MHzand, allo wing. for the onboard d i­

vide-by-two's reducing the LO to

1152 1\1Hc; we might be able 10tap off that line and use it in this

applicat ion. I will have to Iry tofind some time to try this modifi­

cation and see if it is practical ;

more on this later. Th e ac tual syn­

thesizer thar I used is in the lestbed area of my shack and I am in

the process of docu menting it.While it is an excellent choke, we

do have a q uanti ty of them and

have not fully developed details for

others to follo w our conversion at

this time. Also, this un it will prove

to he cost ly because it co mes

equipped with a high quality 10MHz TCXO on the PC hoard, this

in addition to the 3036 synthesizer

circuitry.In the prototype convers ion we

were able to not on ly ge nerate therequired 115 2 MH z for the

conve rter's use a t 1296 ~1 11z

transverter use, but also to use all

additional oscillator port to drive a

3 .7 to 4.2 sate llite LNA bybroadhanding its strip line ctrcuitry

to serve a harmonic amplifie r. This

LNA feeds a simple PC board a n­

tenna feed of tnband proportions,mak ing harmonics avai la b le for

2304 Mllz, and 3456 ~1Hz and

higher harmon ics available for call­

bmtion at other amateur frequen­

cies. These frequencies are di rect

multiples of 1152 MHz.

I have tried both the CATVtuner's local oscillators and had

some trouble increasing frequency

higherto make it run at 1152 Ml tz.Normally the CATV tuner 's uppe r

frequency li mits are near 1050

MHz and require modification to gohig her. While the 3036-based syn­

thesizer is much more complex . itis also the best local oscillator I have

tried. Howe ver. it's somewhat ex­pensive considering it comes wit h

a 10 \1Hz high stability TC XO ref­erence . Whatever local oscillator

you se lect , this RF amplifier/mixer

arrangement should prove quite

easy to set up fo r a simple 1296

MHz converter.T he Ij-: a mpl ifiers provide gain

over a 800 to 1700 MH z range.

THe receiver IF ampl ifier pro­

vides so me 30dB gain and exhib­its a 2 dB noise figure, making a

very good fro nt e nd for a receiverconverte r. T he transmit IF ampli­

fie r is a lso well su ited for lo w

power applicat ions. or as a first

driving a mpl ifier. As it stands it

provides +10 d B output powe rwhe n driven fro m the mixer. Nor­

mally it has 25 d B gain but will

o nly provide + I0 maximum satu­rated all! power in transmit. As

both uni ts run from a regulated

+ 10 volts they are easy to usc as

they o nly require a n in put a nd

o utput RF connection in addition tothe +10 volts a nd ground.

In my application I mounted the

amplifiers on the PC board with the

receive amp faci ng forward or len

to right. and the transmitting ampreversed with the receive amp. In

this way I could use only one input

and output RF connector and mountthem on the side wa ll, whic h is

about 3/4"' high ,U1d constructed out

of PC board material cut to length.All four sides are 3/4" high and sol ­

dered togethe r. Another scrap of PCboard material will se rve at the top

cover plate.I mounted the two miniature

TO-5 m iniat ure relays as dose to

the coaxial connector for mini­mum lead length. I also soldered

the re lay coil with m inimum lead

length to ground. P lace a rect ifier

diode across the relay coil fo r DCsuppression. Pos itio n the o ther

contacts as best you can to the

input and output of the ampl ifiera t their respect ive ends of the

compart ment. Sec Fi~, I for mypart ic ular layout. Exact replica­

tion of my layo ut is not necessary

as long as your lead le ngth is asminimum as you can ma ke it.

Remember that you a rc working

at 1296 ~1Hl and short leads are

necessa ry.TIle amplifiers both have input

and output pads, making easy con­

nection to thei r PC hoard ci rcuitry.No adjustment or modificat ion is

necessary (() their circuits; they can

he used as they come. I soldered the

PC hoard ground foi l to the bo tto mcircuit, mak ing the amplifiers' PC

hoard ground common and direc t

to the mounting bouom c ircuit

board foil. I also mounted a th irdrelay to switch the + I0 volt OC line

to eit her the Rx or Tx amplifier.Mai n DC input to the unit is 12 voltsno minal and I used a 78 10 volt age

regulator mounted inside the case

for the regulated DC su pply.This relay coil for the DC switch

dist ribution is fed to an ex ternal keylead, making both the input andoutput CO,,'lX (m iniature T0-5 relays)

switch when the DC control relay

is also switched from this commonkey lead. In the non ke y condit ion

DC po we r is supplied to the receive

amplifie r. When thc key lead is en­ergized the rccet ve amp goes open

and DC power is supplied 10 the

transmitti ng amp and switching

relay coi ls to energ ize them Intooperation.

T his keying sequence ca n bechanged to g round depending on

your particular switching condi­tions. You don ' t have to fo llow my

condit ions; if yours arc d iffere ntmake in ternal changes-don't

modify your other equipment. If

your keying conditions su pply

ground, tic the switching relay 10

+ 12 volts and run the open end tothe switching lead . Bypass this lead

wi th a feedt hrough capacitor and

ground to the transmit switch on

this lead.

1 1 1 1 1+10 VDC45mA

TXIF Out

1 1

1 1

TXIFIn

uPC-1659Fig. 3. Schematic diagrum ofThe Transmit amplifier.

73 Amateur Radio Today · January 1997 61

DON'T MISS THIS ONE!

Photo A. Completed converter unit. lower lef t corner ofRF housing.Mixer mounted to upper part of converter case and waveguide fil ter(jar 1296 MHz complete low level transverter system) to rear left ofphoto (requires LO at 1152for complete package).

to use? Well. it doesn't mattermuch as both the iron core par­ticles and the black conductivefoam present a very high imped­ance or resistance to RF from cou­pling bet ween the input andoutput of the amplifier.

If you use broken ferrite corematerial, glue the small brokenpieces to theunderneath side of thecover plate. This also will help toplace a lossy substance in the pathofthe oscillation, thereby reducingthe case's susceptibility to aidingoscillation. If you can figure outwhere an amplifier is getting itscoupling from input to output youcan stop the oscillation using oneofthese tricks Ijust mentioned. It'snot hardbutitdoes take some smallamount of time to make a verysta ble amplifier system whenplaced into metal containers. Theyall act like waveguide and coupleso be careful and test each andeveryone you build to preventunwanted oscillations.

Next month I will get into sev­eral dish antenna feeds that can beconstructed, and cover several thatwere obtained from surplus.

Concerning the 800 to 1700MHz amplifiers used in thismonth's project I will make themavailable in a kit containing boththe Rx and Tx amplifiers with a2000 MHz surface-mount mixerand a short section of waveguide17 toconstruct the evanescent modefilter. for $20 postpaid.

Well, that's it for this month.Next month I will covermicrowavestriplinc tuning methods. 73 ChuckWB6IGP. IllI

Photo B , Full view of transverter package for 1296 MHz converter.Additional PC board on bottom right is RF relay switching for 144MHz IF changeover.

The best answer to preventingthis effect is to bypass the powerand switc hin g leads with afeedthrough capacitor. Use smallrelays for coaxial switching, makeground connec tions as short aspossible and use as direct wiringas possible. In some stubborncases it might be necessary toconstruct some small case-highinternal shields constructed out ofsmall PC board scrap pieces andsolder them to the common bot­tom ground surface to serve agrounded separator.

The cover plate can also be asource of trouble when it is at­tached. Let' s suppose that youhave just finished the amplifierlmixer unit and all tested out OK.It sounds just fine and you are sat­isfied with this amplifier and havetested switching and all is stillOK. However, when you put thecover on the noise in your re­ceiver increases or some othereffect is in apparent. like the pres­ence of "birdies in your receiver."What' s up?

Well, chances are the containeris acting like a short section ofwaveguide with an input and out­put connector serving as the con­nectors to a waveguide to coaxialtransition, and we have resurfacedthe old alligator trick again (whenthe cover is placed on the ampli­fier)! TIle solution is to remove thecover plate and place some blackconductive foam and glue it to theinside of the cover plate. Othermaterial can be used, even someiron particles from a smashed irontoroid core. What type of material

crosstalking?Well,anotherterrn forthis is the venerable alligatoreffectknown as oscillation. The only dif­ference between an oscillator andan amplifier is that a good func­tional amplifier will not oscillate.However. if you give this amplifiera chance by coupling between theinputand outputcircuits it will takeoff and f1 as a oscillator.

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The only important part of con­struction on this RF amplifier is torun leads to the input and outputswitching miniature relays in asshort as possible a path to reduceloss and prevent unwanted stray ef­fects like lead crosstalking, whichis undesirable. What is lead

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Preventing trouble

62 73 Amateur Radio Today. January 1997

Assembly

lie s main ly in the choice of ICs

used . Instead o f the 40 I I, a 4093

is used. A 4013 re places the 4027

used in the D Y I kcycr. Also , th is

keyer has an onboard I kHz ke y­ing monitor. It will drive o ne o f

th ose piczo unit s. I' m not sure Iwould like to use o ne o f those fo rstcerone mo nito ring!

Note that this ke yer is laid outso il is very narrow and only one

inch wide. It wo uld fit alo ng thebacks ide ofjust about any QRP rig.

The re lay T X o utpu t will ensure

total ke ying compatihility.

makes the kcyer much smaller than

theoriginal verskmon its single-sided

PC board. And, there was enough

room to add anextra transistor and a

reed relay.Thi s relay allows the keyer10 key transmitters using emitterkey­

ing. Uyour QRP tran.smitter requiresthe emitter ofthe oscillator transistor

to be pulled to ground. a transistorswitch may not do the j o b ad­

equately. The results are usually abag of unwanted chirps and tweets.

Because the C MOS chips willoperate OIl a wide range of power

supplies. Ididex usc any intire regu­lators. I ....ould steal power from a

regulated SOUfl'C from your rig. TheCMOS will be happy with anything:bcrween S und 16 volts. Current de­

mand for either of the kcycrs in this

trio is just about zip. Only the relaydemands a stiff amount of current.

T he relay I used in the DYI Plusis an off-the- wall ite m at Radi o

Shack. It comes in two di ffe ren tvo ltages: 5 volts and 12 volts. If

you run your D Y I Plus from a 12volt source, guess w hat re lay you

should use '! The re lays ha ve the

following Rad io Shack numbers:for 5 volts, 27 5-232; for 12 vol ts,

275-233. M ouser electronics also

se lls these re lays.W hen I d id this version of the

keyer, I added a header to the cir­cuit b oard on , I00 centers. M y idea

is to lise those cute shortingjump­

crs and a header to select between

G3BIK's keyer

relay keying and solid-s tate key­

ing. There is no reason why you

can' t use a cl ipped resistor lead

instead of the shorting j umpers.A nd, there is enough current from

the 4027 to drive both transistors.Th is way, you could ha ve two o ut­

puts, although why is beyond me,

S peaking of headers, I a l so

laid ou t the hoard to acce pt .100"

heade rs for the speed po t and a ll

the l i a s. I just ha te seeing aproject with a zill ion wires sol­

dered i n p lace . The use o f the

p lug - i n headers ma kes for a

much cleaner insta llat ion. If youcan train yourself to use a stan­

dard heade r, you co u ld switch

out o ne keyer project fo r anothe r.

No rocket science stu ff here . Ifyou have assembled a fe w kits now

an d the n, you should be able to get

al l three of these to work.

T he o nly cautions arc to handlethe C MOS chips carefully; the y're

subject to damage caused by static.

T he ICs m ust also be in sta lled

correctly, Re verse o ne an d it's al­

most a sure bet it's ro ast. I'd usc IC

sockets, especially on the dou ble­

sided PC boards. The prototypes I

lnade had plated through foles.Hyou

deci de to make your own double­

sided boards, be sure to solder the

connections on both sides of the

board.I'd usc a 9 volt battery to test

out these keyers. There's no needfor large high-capacity ge lled bat ­

teries. In fact. just in case you have

something o ut o f wh ack. you'll do

link damage with the 9 volt hat­

tery. On the other hand, yo u can

easily bu m off copper traces with

a gel cell.I've b u il t t he D Y I Plus kcycr

and the Curtis keye r board.

T he y work j ust f in e . I ha ve no t

as semb led the G3BIK kcycr.Again, I'll ha ve all the files up­

loaded to the Q R P section o nCompuxerve. And, of course, the

QR P sectio n is hid ing inside

HAM NET. If I come up with any

changes to either the boards o r theschematics, I' ll ha ve the updatesin those libraries.

If there is enough interest, per­

haps a small run of double-sided

PC hoards with plated through

holes will be made for the DYI

111e last keyer in ou r trio is by Plus keyer.

G 3B1K, and comes from the Oct. Next mo nth f'lI have some more

1994 issue ofRadioCommunicanon. odds and ends fo r various ci rcuits

Th e circuit is very similar to that you can usc fo r your latest Q R P

of the DYI kcycr. The di ffe re nce projects. Fa73 Amateur Radio Today · January 1997 63

www.mouser.com.

You can also obtain the Curtischip from Jade Products at I-sm·523-3776 . The ir web s i te is:

w ww .ha mpstea d .k I2 .nh .us/-djade/index.html. Jade Prod ucts

also se lls a C urtis keycr kit a t

$46.20 PP. It is not the same onepresented here , however.

Rig h t no w, I' m no t su re PCboards will be available. It' s pos­

sible I may be able to tal k FAR

Ci rcuits into making some of thesingle-s ided boards. I w ill let you

know if any of the boards will bemade.

Low Power Operation

Number 63 on your FeOObac lt. CI/rd

Although many versions of the

C urtis ke ye r have appeared, this

version has most o f the feature s,withou t making an overly complex

project. Also, this ve rsion does notrequire a double-sided PC board.

Assembly is very basic. There 'snothing reall y special to WOITy

about. I would suggest, however,

tltat you use a socket for the Curt is

chip. The ch ip is a hit pricey:

As you can see in the overlayfor the PC' board, many of the con­

trols for speed, sidetone volume

and so o n are mounted d irectly tothe PC board. I would mount the

speed co ntrol off from the board

so you can easily change its set­ting. Aside from the speed control,

leave the others as shown.

Yo ur loc a l Rad io S hack"should be a ble to supp ly you with

almost everyth ing you will need .

Rad io Shack also carries a n ice

selectonof project boxes 10 put thekeyer in. The PC board is a bit large

to fit inside some of the QR P rigs

o ut today. Th is ke yer would be ae xce llen t choice for a benc htop

unit.Rad io S hac k won' t have the

trim mers nor the C urtis kcycr chip .

Yo u can get the trimmers and theC urtis kcycr chip from MouserElectron ics. l - 8 00· 99 2~994 3 .

Po int your browse r at thei r Wo rldW ide Weh address a t

The DYI Plus keyer

This is an old favorite of mine.

111is time around , l've changed the

layo ut a nd put the c ircuit o n adou ble -sided PC hoa rd. T hi s

QRP

The days in January are alwaysgray and col d in Ohio, so let' s be­gin the new year with three con­struction projects.The projects aresimple to build and they are use­ful. too. They ' re electronic keycrs.

To make it easier for you tobuild these keyers. all the artwork

has been laid out in Circad w fo r­mal. You can get a copy of Circadfrom any ofthe larger tclcom sup­pliers. 1know CompuServehas thelatest version. AOL more thanlikely docs as well. The demo ver­

sion is usable, but some featuresarc locked out. You ca n edit andprint out these files wi th the demo

version.

I wi ll post al l o f the file s for th iscolumn. except fo r Circad, in the

IIAMNET forum. InsideHA~INET, the files will be in theQR P li b rary section. All threeprojects will be in the libra ry, and

one file will have all three projects

together. So. you can downloadone, two or three files by the m­

selves, or one fil e with all threep roj ec ts . All files wi ll be in

Z IPPED format. You 'll need

PKUNZI P o r another unzippingprogram to view the fi les.

Because Iwanted as many ham"as possible to give the se kcycrs atry, subminiature parts ami super­small PC boards were not used . In­

stead , the layouts are large enoughso even a no vice in home-brewin g

can have a very good chance of

building a worki ng project.

Two of the kcyers were laid outby Ja y Graswell WB0V NE. Iworked on the last o ne , the DY I

Plus keyer. One of the keycrs is

built on single-sided PC board; tworeq uire a double-sided PC board.

Michael Bryce WB8VG E2225 Mayflower NWMassillon OH 44646

T he fi rst keyer is a classic.Based on the Curt is keyer on a chipIC, the original project was done

by Pa ul Page N IFH and Bo bShriner WA0UZO. The wo rk ap­

peared in the Dece mbe r 198 3

issue o f QST magazine.

The Curtis keyer

Number 64 on your Feedback clJrd

f\adiO\-\a{l\

fUn

Communications Simplified,Part 13

Peter A. Stark K20AWP,O. Box 209

Mt. Kisco NY 10549

Characteristic impedance

Fig. J. A Jimp/(' series f"irn/i, .

64 73 Amateur Radio Today · January 1997

. ta voltage across resistorreS1S nee = .current through It

So . if we had a voltmete r and ammo­tcr connec ted at the sw itc h, we couldsec 10 volts and 0. 1 ampere entering theline as soon as the swi tch doses. A half­second later. that voltage and currentreac h the middle of the line: one seco ndlater they fi nally reach the resistor.

T he problem is that 10 volts and 0.1ampere are all wrong for a lu-ohm rc­sistor. By Ohm's law. if there is 10

vo lts. there should be I ampere: iI' therei... only 0.1 ampere. then there should heonly I vo lt. The resistor therefo re looksat the voltage and current reaching it.and ...ays "No. no . ne-e-something iswrong-there is either too little current.or too much voltage-c-or perhaps both!"

The resi stor therefore short circuit..some of the applied voltage to bringit clo..er in line with what sho uld hethere. considering the amount of c ur­rent. This temporary short circuit causesan additional current to llow throughthe resistor as " ·eIL

the wire has no resistance. hu t it docshave a characteristic impedance ~ ofperhaps 100 ohms. What is the currentjust aft er we close the switch'!

Since it takes light one second totrave l the distance from the resistor tothe ...witch and bailer)'. eve n if the bat­tery had a high-power tel escope so itcou ld "sec" the res istor a t the far end. itco uld still not know precisely what is a tthe end of the wire a t the instant the..witch closes- it could only sec whatwas there one second earlier. So. as be­fore. the current it sends o ut dependsnot o n the resistor. hut on the cha racter­istic impedance of the line. The curren tis there fore :

JO volts1= 100 ohms = 0.1 ampere

Now look at Fig. 1. Here we sec as imple circuit. consisting o f a 10-\'01tbattery. a swi tch. and a to-ohm resi stor.all connected in se ries. Righi now. theswitch is sho wn open. and so there is nocurrent. Once we close the swi tch. cur­rent starts to n ow. The va lue is given byOhm's law as V = IIR ; thi ... works OUI to

10 volts/ !0 ohms. or I ampere.BUllet's complicate the issue a bit by

making the wires between the switchand the resistor I 86.0m miles long . Tosimplify thi ngs a bit. le t's assume that

Reflect ions

current Ohm's law wants. In this case.however. that test current just keeps gu­ing forever (at a lmost the speed oflight). searching for a resi stor that isn' tthere. The ohmmeter doesn't kno w thatthis test current never reached a res istor:it happily mea...urcs the current and vol t­age. and displays a val ue of res istanceanyway.

The amount of current that flo ws de­pends o n the kind o f cable . Actually, itsresi stance has fairly little 10 do with it:irs the capacitance between the twowires and the inductance of the wiresthat mainly determi ne how much cur­rent fl ows down the cable. The resis­tance the meter measures thereforedepends on the type o f cable: we call itZw or the characteristic impedance ofthe cable.

Diffe rent cables have differe nt char­acteristic impedances- the TV twi n­lead is 300 ohms. the coaxial ca ble usedfor TV antennas is 75 oh ms. while thecoax generally used for transmitting an­ten nas is 50 ohms, And the twisted-paircable generally used fo r audio and tele­phone ci rcuits would measure 600ohms.

)

100-- IOV

Let's review what we said about char­acteristic impedance earlier in this sc­ries. Think for a moment about how anohmmeter works. Ins ide every ohnunc­ter is a small battery. When yo u connectthe ohmmete r across a resistor. themeter connects that battery aero..s theresistor. C urrent starts to no w throughthe resi stor. the meter measures ho wmuch current there is, and co mputes theresistance from Ohm 's law:

Now. imagine that yo u have an in fi ­nite ly long leng th of some cable. suc has the n at tw in-leal! cable used for TVantennas. and yo u connect the ohmme­ter between the two wires at your end .What will yo u measure"

Connecting the ohmmeter to the endo f your cublc con nec ts its battery acrossthe two wires, The ohmmeter. o f course.doesn ' t kno w whether there is an inch. afoot. or a mi le of wire there. so it sendssome current out its test leads. hopingeventually to reach a res istor at the end.Normally. the current would reach a re­sistor aft er going through j ust a few feetof wi re. and scnlc down to whatever

It'S time to look at the transmissionIinc~ that cn nnect. the antenna to areceiver or transmitter.

Fig . 2. Time -domain ref tectometry,

Reflections in digital circuits

Fla. 2 shows a simple test ci rcuitwhich we can rig up in the lab. At the

oo -Zo 00- 10 00

r = oo+ZO= oo + IO = ~= + 1

That's because the infinity on the topand bottom arc so big that we might aswell ignore the ~. So. with the outputope n. the reflec tion coefficient is +I. and100% of the ou tgoing signal is re­flected.

Case 2: If. on the other hand. the end o fthe cable is shorted. then Zl is ze ro. andthe eq uation becomes:

left we have a pulse ge ne rator; the pulsege nerator acts sort of like a battery andswitch, except that it closes the switcho nly for a ver y short time (sometimes assho rt as j u..t a few billionths o f a sec­ond ). In other words. it connects a vo lt­age to the line for a tiny instant. andthen immediatel y disconnects it again.The pulse generator feeds a length o ftransmission line (we usc 100 feet o fRG-58 coax cable in o ur lab experi­ment ). whose far end is shown ope n. Afast oscilloscope is connected across thepul se genera tor to show us the signal.Fi~. 3 shows the result . T he fairly

sharp pulse at the left is the signal com­ing ou t of the pulse generator. It appearsas a narrow pulse, o n for j ust a veryshort time. The slightly smaller pul se atthe right is what comes bad from theend o f the line-this is the re flec t ion. Itis slightly smaller, because there isabout a 10% loss of voltage in goingdo wn the cable and hack (th is is. aft erall. a practical cable , not a theo retical,loss-free o ne). Note also (hat the return­ing pu lse is slightly wider and notnearly as nice and square. T his is causedby the various parts o f the pulse travel­ing down the cable at slightly differentspeeds. which results in the pulsespreading slightly.

h om this picture. we could calculat ethe signal loss in the cable; m uch mo reinteresti ng , though. is to calculate howfa st the signal travels. In this picture.the scope sweep was set to 0 .05 micro­seconds pe r divis ion; since the spacingbetween the two pulses is abo ut six di ­vis ions. the delay between the o utgo ingand returning pulses is abou t 0.3 micro­seco nds. In that time. the pulse trave led200 feet ( 100 feet fro m the generator tothe end. and ano the r 100 feet to return ).The signal velocity is therefore:

6.67 x 108 feet/sec

Since there arc 5.280 feet in a mile ,thi s works out to about 126.000 milespe r seco nd . Note that this is slower thanthe speed o f light. which is usuallygive n as 186.000 miles per second; thisla tter fig ure is o nly tru e for light in avacuum anyway. no t for light in ai r.g la..s, or other materials .

73 Amateur Radio Today . January 1997 65

velod = di~tance = 200 feet =ty ume 0.3 usee

r = 0 - Zo = 0 - 10 = -10 = -1O+ ZO 0 + 10 + 10

In this case, the reflection coeffi cient is- I. and so - J(Xl% of the ourgoi ng vo ltageis reflected. 1113t is. it is all reflected. hutthe polari ty changes (that's what the mi­nus sign means). Thai makes sense, sincethe voltage at a short circuit must he zer o;the only way to get this is if the outgoingvoltage and the returning voltage exactlycancel each other our.

Case 3: Suppose, on the other hand.(hat the load resistance Zl is exact ly equalto ~'? In that case. the numerator of theequation becomes z., -z." which is zero.The reflection coe fficient is thereforeZCTO. and nothing is refl ected at all.

So we sec that the only way to get noreflection is to load the end of (he li newith a resistance exactly equal to the char­acteristic impedance o f the line itself

Let 's sec how reflections in cablescan cause problems.

Pul",

Generator

What this means is that 8 1.8% (a fmc­tion 01' 0 .8 18. or 8. 18 volts) of the outgo­ing 10 volts will reflec t off the I-o hmresistor. The voltage across the resistorwill then be 10 - 8. 18 = 1.82 volts. Kno w­ing how much voltage will actually reflectis nice. of course. but it's more interes tingto look at three special cases.

Case 1: There is no load resistor atthe end o f the cable at all-the output isopen. In this case. ~ is infinity, an d theequation becomes :

ZL - Zor=ZL + Zo

This si tuation. howe ver. leads to acontradiction. At the resistor. the vo lt­age is now lower than 10 volts wh ile thecurrent is slightly higher than the origi­nal 0.1 ampere . Ho wever. ,I short dis­tance hack from the resistor the linevoltage ami current arc still 10 vo lts and0.1 amperes. But this can' t he ! In a par­allel circuit. the voltage must he thesame everywhere. while in a series ci r­cuit the current should he the sa meas well . And so the drop in voltageand increase of current must start totrave l back along the line . eventuallymaking the voltage ami c urrent thesame every where.

One way to look at this is to think ofan outgoing signal ( 10 volts and 0.1 am­peres) trave ling fro m the batte ry to theresistor. and a second. returning signal.traveling back: from the resistor to wardthe battery. The returning signal adds to(or subtracts fm m) the outgoing signal.changing the total voltag e and currentalong the wire. In technical te rms. wesay that the returning signal is a reflec­tion - part o f the outgoing voltage an dcurrent have been reflected fro m theload. and travel hack along the line.

T he refl ection will e ventuall y reachthe butte ry, whic h willlook at the lowervoltage. and do everything it can toboost it back to the required 10 vo lts. Inthe process, it will send ou t a hurst ofmore voltage and current (hut still thewrong va lues). T hese will go hack tothe res istor, cause yet another rcf'lcc­tion, ami so on. Eventually. the voltageand current will stabili ze at the to voltsand 1 ampe re that DC c ircuit theorysays we sho uld have.

We can calculate how much voltage isre flected fro m the reflection coefficient,represented by the capital Greek lettergamma:

r = ZL - ZQ =ZL + Zo

100-1090100 + 10 = 110 = 0.818

where Zl is the va lue o f the load res istor( 100 ohms in th is case). while Zo is thecharacteristic impedance (which is 10ohms in our example). So in th is case,the reflection coefficient is :

The ve locity factor b th us:

Jj

Why the careful impedance match-ing? Because reflections can cause de-lays. If ..o rne of a received TV sig nalwent direc tly to the TV set. while asmall portion o f it was reflected fromthe se t back to the antenna. and then re-fleeted a seco nd time from the antennaback to the se t. the TV set would get aweak signa l short ly after the main .strong o ne . T his would cause a ghostimage to appear to the right o f the mainimage. (If yo u get ghosts in your TV im-age. don' t immediately blame the an-tcnna installat ion. Ghosts are also oftencaused hy reflections from nearbybuildings. hill s . or other large o bjccts. )

But there is a seco nd way to look atreflections o f analog s ignals. Let's sup-pose that the s ignal entering the coaxline in Fig. 5 is not a pu lse. but a sinewave . The reflection will then also be asi ne wave. rather than a pulse . Depend-ing on the length of the line. that rcflec-tion could arr ive at the beginning of theline at va rious times. So let's examine afew spcciul cases.

Case 1: SUpJXl"C that the line is ex -act ly one-quarter o r a wavelength long.and its far e nd is open-circuited . We ear-lic r defined a wavelcneth as the dis-cranee a signal travels in the time o r o necycle. The equa tion for the wave lengthlambda was:

A = velocityJrequency

For the velocity. of CUUTSC. we nowhave In take the velocity in the cable. andwe have already learned that this veloci tyis smaller than the speed of light in avac uum; it is the ..peed of ligh t times thevelocity factor for the particular cable.

Let 's put some numbers on this . Sup-po se we usc an RG-58 cable wi th a ve-locity factor of abou t 0 .65. and a

L

~dIon.:l from

•I -•

IFiN. -I. Ne Iection ;-0111 {/ had /0(1(/ .

Reflecti ons in a nalog circuits

connected to a load resistor at the end ;sometimes the resistor will be inside thecomputer interface card. other times itmay be mounted externally, hut it willalways be somewhere . And since thesignals in these cables can travel ineither direction . there will be a termina­tion resistor <:I t eac h end of every cable.

Incidentally, putt ing a proper load re­s istor at the end of the cable is no tenough- ho w yo u connect it is impor­tant too. If that resistor is right at theend of the cable. wi th short lead s. all isfine . But Fi~. '* sho ws what happe ns ifthat resistor is connected with foot-longcl ip-leads. There is still a small reflec­tion; in fact. there are now (wo small re·flect ions. At point A is a small positivereflection. cuuscd by the cl ip-leads . Thetwo cl ip-leads make a small tran smis­sion line. but its characteristic imped­ance is higher tha n that o f the coaxcab le. So we gel a po sitive reflection atthis poi nt. A foot later. the terminationresistor has a lower resistance than thecl ip-lead impedance. and so we get asmall negative reflection at point B.Thi s points out that this type o f test.called lime-domain reflectometry (orTOR ) because it measures the refl ec­tions and the time they occur. lets usanalyze the loc atio ns of shorts andopens, as wel l as the locatio ns of badconnections. Commercial TOR instru­ments are thus very use ful for fi nd ingproblems in buried or hidden cables .

Analog signals can be reflected fro mthe ends of cables just as digi tal onescan. For example, consider the antennalead from a TV antenna to the TV set.To prevent reflections. the characteristicim pedance o f the cable usually matchesthe impedance o f the an tenna. and theimpedance o f the l Vset's antenna in­put. Since there arc two kinds o f com­mon antenna leads in usc- the nat"twin-lead" cable which has a Zuo f 300ohms. and T V coax with a Zo of 75ohms-many TV sets have two separateinputs as well. TV antennas usuallyhave a 300-ohm connection. but \Io'C of­ten use a 75· to 300-ohm tran ..former tomatch it to coax cable. (There 's a 'iCC­

ond reason , too-c-tbe 300-ohm twin­lead is a balanced lead. whereas thecoax is unbalanced. so slightly di ffe rentconnectio ns are needed.)

I,I

•Fig , J Reflection from (11/ open Cl f( 'IIIt.

66 73 Amateur Radio Today · January 1997

In our electrical case. the speed of thesignal in the cable is only about 67% ofthe speed of light; we call this number thevelocity factor of the cable. and usuallywrite it as 0.67 rather than 67Ck. (Rcmcm-

----.;cr that our measurement is only an ap­proximarion: the actual published velocityfactor for RG-58 cable is slightly less. butthe delay time is hard for us to read fromthe scope. and so 0.67 is about 'L'i close aswe're goi ng to gct.)

Now imagine that the pulse in Fi~. 3is just one of many pulses be ing sent ina cable. perhaps as pari o f a computerlocal area network. If the end of thecable is open , then the pulses reflectedfrom the end will get mixed in with theoutgoing pulses and cause major errorsin the system . So rcf' lcc tions can be abig problem.Fi~. 3 dealt with a line whose far end

was ope n. If the fa r end had beenshorted. there would still be a re flec tion.but the refl ected signal would be ncgu­tive instead of positive.

From o ur previous discussion. we cannow see that the on ly way 10 prevent rc­flections is to make sure thai the end o fthe cable is properly terminated- wemust place a resistor at the end of theline. and make sure that its resistance isequal to the characteri stic impedance ofthe line. If the resistance is slightly off,there will be a rcffection. but it mightnot he large enough to mailer. In gen­eral. a resistance larger than the charac­teristic impedance will provide apositive reflection ; a resi stance smallerthan the characteristic impedance willprovide a negative relleetion. Thus thecables in local area networks are always

.' _ actual speedvelocity factor - speed o f light

Sine-wavegeneratorl~;;~JfT~=========±lr No

connectionat end

frequency of 1.6 MHz. One wavelengthis then:

A = 186,000 miles per second x 0.651,600,OOOHz

Oscillo­scope f-

25125 = 0.2

c

75 - 5075 + 50

short

Fig. 6, each part a quarter of a wa ve­

length. Since the right end of part C isopen, the left end of it looks like a short.Part 8 is therefore shorted at the right,so its left end looks open. Finally, part Asees an open at its right end, so its leftend looks li ke a short. So a 3/4~wave­

length line which is open at the far endlooks like a short at its input.

We can extend this reasoning to any linewhose length is some multiple of a quarter­wavelength, and which is either shorted oropen at its end. But what about other lines?

More complicate..-d cases

In most cases. transmission lines willnot be an exact multiple of a quarter­wavelength, and they will not have anexact short or open at their end. Whatthen?

The mathematical analysis of suchcases is fairly difficult, and most profes­sionals wi ll use a special kind of graphcalled a Smith Chart to figure out whathappens. But even without the SmithChart, we can still get a general idea ofwhat is going on. So let' s consider thecase in Ffg. 7 , where we see a transmit­ter feeding a 75~ohm load (most likelyan antenna) through a 50-ohm transmis­sion line that is 1.68 wavelengths long.

Because the load resistance IS notequal to the line's characteristic imped­ance. there will he a reflection . Thereflection coefficient is:

73 Ama teur Radio toasv » January 1997 67

nopen

~--------3/4 wavelength--------~

A

short

The signal takes a quarter of a cycleto reach the short. Because the rcflcc­tion coefficient I" at a short is equal to ­I, the positive half of the sine wave iscompletely reflected, but the minus signmeans that it becomes negative ratherthan rernammg positive. Thi s signalnow takes another quarter of a cycle toarrive hack at the signal generator, ar­riving exactly a half of a cycle after itleft.

Let's stand hack and think about thisfor a moment. The positive half of acycle left the generator. was inverted atthe reflection. and returns just as the gen­erator is outputting the fo llowing negativehalf of the cycle. The generator is nowtrying to output a negative voltage, hutthere is already a negati ve voltage on theline. So the generator doesn' t really haveto do anythi ng to make the voltage nega­tive. Hence it docs not output any current.How can that be'! The only possible ex­planation is that the transmission line be­haves like an open circu it. There IS avoltage. but no current.

We can summarize this as follows: Aquarter-wavelength transmiss ion linewhich is short-circuited at the far end be­haves like (If/ open circuit at its input.This, too. may be a bit hard to believe. butit is true. Given the right test equipment.you can prove it for yourself.

We can extend this idea to other lengthsof cables. For example, the cable in Fig. 6is 314~wavelength long. What do we see ifwe look into the input?

Let's imagine that the line is split intothe three parts labeled A , 8 , and C in

Fig. 5. Refl ection of« sine Inn'e .

Fig. 6. A 314-1I"(1l"elCllgth line,

= 0.0756 mile

which is about 399 feel. A quarter­wavelength is then about 100 feet.

So let 's take 100 feet of RG-58 cable,leave the far end open-circuited. and senda 1.6 MHz signal into it. The signal willtake exaclly one quarter of a cycle totravel down to the end. Since the end isopen, the reflect ion coefficient I" is +1.and so the signal is completely reflected.It now takes a quarter of a cycle to travelhack to the beginning of the li ne, arrivingexactly one-half of a cycle after it started.Assuming a low-loss line. the signal com­ing back will be almost exactly the samesize as the outgoing signal.

The only problem is that the returningsignal is now exactly one-half of a cyclehehind the outgoing signal. In otherwords. the positive half-cycle of the sinewavearrives just as the signal generator isproduc ing the negative half-cycle. And sothe positive and negative half-cycles ex­actly cancel, producing 0 volts at the in­put into the line. The oscilloscope will seenothing .

Let's think about this for a moment.The signal generator in Fig. 5 is generat­ing a voltage (we didn't specify how big)hut the actual voltage measured by thescope at the input into the line is 0 volts.How can that be? The only possible ex­planation is that the transmission li ne be­haves like a short circu it. There is current.but no voltage.

We can summarize this as follows: Aquarter-wavetengm transmission linewhich. is open-circuited at the far end be­haves like a short circuit at its input. Itmay be a bit hard to believe, but it is true.

One more thing: The generator, thi nk­ing it is feeding a short circuit. is out­putting more than its normal current,trying to overcome that short. So the in­put to the line is a point of zero voltage.but higher than normal current.

Case 2: Let 's now take a similar case,but instead of leaving the far end of theline open-circuited, let's short it and seewhat happens as the positive half-cyclepart of a sine wave leaves the signalgenerator.

Z o - 50.

73 is accepting manuscripts forthe June 1997 Field Day Issue.

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Help

the kids learn about the won­derful world of ham radio.Then wc' Il have the engineers-we' ll need for the next centuryhere in the USA .

so 20% o f the o utgoing volt age is rc­Fl eeted back to the tran smitter. Let ' sassume that the transmi tter is putt ing(Jut 10 volts o f RF; the reflected volt­age is the n 2 volts . T hi s is o bviouslynOI good, because tbe load is nOI get­ling as much power as it sho uld .As the reflected sig na l goes bac k tothe trans mitter. the re will be pointsalong the cab le where the re flectedvol tage will add to the outgoi ng \"01t ­age. giving us more than 10 volt s.Th is vol tage is ca lled V an d is_.eq ua l to :

Vmax = Vforward + Vreflected

In our example. this vo ltage is 10 + 2 =12 volts.

At the same time. there will he otherplaces alo ng the line where the twovoltages are opposite. and so theysubtract to g ive:

Vmin = Vforward + Vreflected

In our example. this voltage is 10 - 2 = 8vol ts .

Ideally. if the load was perfectlymatched 10 the line, the re would he nore tlected voltage, and so V and V

rna:< mInwo uld he equal-the vo ltage would bethe same 10 volts everywhere, and therewould he no maximum or minimum.But that seldom happens exactl y.

Th e presence o f ma xima an dm inima me ans that we can take mea ­surements a lo ng the line. and fi ndthe se po ints of max imum and m ini ­mum . Thi s is not part icul arly practicalwi th coax cable . hut it can he donewi th open-wire balanced line s.whe re you can eas ily get to the wires10 take voltage readings betweenthem It is also so met imes done with

microwaves; microwave signals (i.e..s ignals with a very high frequency onthe order of gigahertz) are usuall y car­ried in waveguides (more on theselater), II 's possible to CUI a slot into awavegu ide and insert a ...mall probe tota ke vol tage readings in ...ide it. T his canhe used 10 measure the VS W R, bUI itcan also be used to find the freq ue ncy,Because the d istan ce from a maximumto a minimum point is a quarter-wave­length (and the distance between twominima is therefore a half-wavelength ).this can be used to measure the wave­length of a signal. If you know thespeed of the signal in the waveguide.you can then calculate the frequency.

We say that these min ima andmax ima indicate the presence o f stand­inK II'{/l't'.\' along the line, and then de­fi ne .1 standing um 'e ratio (also called avoltage standing ware rat io because wemeasure the voltage ). abbreviated asSW R or VSW R:

YSWR = Y JIl?X = V fQrward + Y rel]ectedvmin Vforward - Vreflccted

In our case, this is 12/8 o r 1.5.In the best case , if V and V..... 11Io'.

we re eq ual. the VS W R would he I;many people read th is as " I to I " o r1: I.

In the wo rs t c ase , when everyth ingis re flected , V,_ - V = 0 and

" f'I>--. rd r~J1"" .d

the denominator is zero , so the VSWRis in fin ite , So measur ing the VS W R isa co mmo n way of chec ki ng whethera n antenna is well matched to thetransmitt er and its feedline . ( It is not aperfec t measure , because a resistorload equal to the tra nsmission line 'scharacteristic impedance would pro­duce no re flect ions. yet obviouslyrad iate no signal into the ai r!) ra

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68 73 Amateur Radio Today· January 1997

Fig , 7, A more /ypinJ/ example,

73 W3.I:tts your. feedback •• ~wc ' ve been impro vin g 73 fo r the pastmonths wl.th Ill o~e :~rtlcles. easier readi ng type. etc. And honestly, we need yourfeedhac,k (in dCI.Il I) If you ha ve any critique eithe r for or against the sub tle cha ngesthat we vc made. We know we can"t please everyone e very time, hut if you te ll uswhat you wan t 73 to he , we ' ll at least try 10 head in the direction fo r further"improvements" that might he most appeal ing to you. Thanks.

Number 69 011 y our Ft!(ldback card

Build a Well-RegulatedPower Adapter

Add some stability to your plug-in wall transformer.

James Tarchinski NBPTG3135 Primrose Drive

Rochester Hills MI 48307

As you flip through the pages of73, or any other source of elec­tronics circuit information,

you'll fi nd that many of the circuits e i­the r incorporate or need to be pow­cred ex te rn ally by a posi tive 5-voltDC power supp ly. Five-va ll sup­plies a re by far the most co mmons upp ly val ue used for today 's elec­tronics. Kn owing this, one wo uldassume tha t th ere mus t be doze ns of5-v01l regu lated DC power ada pterson the marke t, right?

Wro ng . The free e nte rprise sys temhas missed the ma rk on this one ­regulated 5-vol t adap ters are nearlyno nexistent, so e lec tronic s hobby­ists ofte n e nd up incorporati ng sup­pli es in to their project des ig ns . Infact. th ey ten d (0 design and buildthese supp lies over, and over, andover aga in . But you don't have tokeep re peat ing yo urself-there is abette r way .

Wall adapters can provide a con­ve nien t way of powering yo ur elec­tronic s projec ts; you j ust need tomodify th em so they have the co r­rec t o utput charac te ristics for j ustabout any regulat ed vo ltage that yo uwill eve r need ! Beca use everyonehas a diffe re nt app lica tion with dif­fere nt des ign criteria, howeve r, wedo not go thro ugh one particu lar de­sign . Rat her we wil l d iscuss how tomodify wa ll adap ters in gene ra l.

concentra ti ng parti cularl y on how to wi ll a ll produce produ cts that ut il izemodify a n adapte r e lectrica lly wi th- a standard fo rmat for sorne th ing.out reworki ng th e basic packaging This type o f a rrangeme nt allowsof th e unit' s electro nics. co mpa nies to save money by joi nt ly

develop ing a new technology, hu tA hit of h isto r y

ye t they can eac h mak e mone y byThe cons umer e lec tronics ind us- se ll ing the ir ow n unique products .

try as we know it today wo uld no t For examp le. before a ny co mpanyexist if i, we re no t fo r " ind ustry sold a co mpac t disc (C O) player, a llst andards ." Ind ustr y standards a rc the major a udio manu facturers ofessent ia lly gentlemen's agree me nts the wo rld agreed on the spccif'ica-among compa nies sta ting tha t the y tio ns for the d isc fo rmat. Fro m the

#Labeled True

% ErrorVoltage Voltage

1 +5 5.10 2.0%

2 +5 9.65 93%

3 +6 7.94 32%

4 +6 8.42 40%

5 +9 10.34 15%

6 +12 12.38 3.2%

Table I . "Don't believe everything you read." The true output voltage can differ from therated voltage ill II random stlmpling of DC adopters , Adapter #2 was the wont unit tested,with all Oil/pill nearly double the voltage listed on its case .

73 Amateur Radio tcaey » January 1997 69

3 == Regulated Voltage Output

2 == Ground t Input &. Output

1 == voltage Input

, 3

oFn>n1 View

Fig . J . Pinout of the 78.u serie s of l'o/taKt'regulators,

F ig. 1 is the schemati c fo r a verysimple AC -to-DC conve rte r. whi leP lg, 2 is the associated hoard lay­out. As you can sec. the ci rcuit con­tains nothi ng more than a standardfull -wave diode bridge rec tifier anda s ingle filter capac itor. While th isdesi gn is cheap. the voltage outpu tis not very stable and there foreprobabl y not suitable for any ofyo ur projects that use integratedcircuit s ,

The circuit can be easil y modifiedto incorporate a regulato r. however.It is the job o f the regulato r to stabi­li ze the ad ap ter 's DC voltage over awide range of inpu t vo ltages andoutpu t curre nts.

One o f the mo st commonly usedtypes of vo ltage regu la tors is the7l'lxx series. Lo w cost an d the avail­ahil ity of se veral regula tio n vol t­ages arc amon g the reasons for thepopularity of thi s line , Tuhle 2 is alist o f regulato rs incl uded in the78xx se ries.Fi~ . 3 is the pi no ut of a 78xx

regulator in a TO-22 0 case . Whenviewed from the fro nt, the leftmostpi n (pin I ) is the inp ut voltage line,which must be supp lied with an in­put voltage that is at least 3 vo ltsgreate r than the device ' s spec ifi edou tp ut voltage . Pin 2 of the de .... ice

The var iabi lity of a poweradapter ' s output is the main ob­stacl e to using it to run circ uits con­taining integrated circuits. One ofthe simplest ways o f ov ercom ingthi s obstacle is to inst al l a voltageregulator on the DC out pu t side ofthe adapter.

T he electrica l design

/i"'- C1

DHIDiode Bridge

even sizes of plugs c urrently usedwit h these devi ces . And finally ,there are plugs on the market thatare wired with either polarity-withthe tip be ing pos itive and the rin gbeing negative, or vice versa .

Another problem with plug-i nAC-to-DC supplies is that theydon ' t always outpu t the vo ltage in­d icated o n their cases! To ill ustratethi s point , I surveyed six differe ntsupplies. each made by a differentma nu fac turer. while in the best casethe ac tual outp ut voltage was within2% of the rat ed voltage , the wo rst­case su pply was off by a whopp ing93 % (see Ta ble 1).

There arc a num be r of reaso nswhy the ac tua l o utp ut voltages ofsupplies arc so d ifferent fro m thei rspecified values, hut by far the mostcommon is cos t. In orde r to mak ethe sup ply as cheap as possib le.most do not have so lid-s tate regu la­tors incorpora ted in their des ign. sotheir output varies directly with theli ne vo ltage supp lied by the powercompany. Also as a cost -cutti ngmeasure, very li beral to lera nces areused in the manu fac ture of thesedevice s, and there is gene ra lly alot of unit -to-uni t variability inperfo rmance .

The load bei ng driven by the sup­ply is also an important fac tor in de ­termini ng its net ou tput voltage . Forthe data presented in Table I, all thesupplies were tested in their o pen­ci rcuit configuration. But when anadap ter is supplying its rated cur­re nt the o utp ut voltage wilt almostalways drop below its ope n-c ircuitvo ltage. Other than b)' testing theudaptcr under different loading con­ditions , there is no way to predic thow far the outp ut voltage will fall .

JI

AC Plug

CI 1>1 U2 IJ.l t l4"",,,"'

L----~T,.Jmnsfol~Ili<":rrt=== _

Fig . 1. The basic tvpe of J'fJ"'t'r adapter. The lack of any semiconductor regulator deviceshelps 10 keep the adapter 's cos t down , but it also keeps the unit 's usefulness down,

Fig. 1 . 1" spite of the limited number ofcomponents _~ fljfJed into the endo:utre uf anuff-tht' .shelfpower adapter. there is /lot gen­naif" milch ~pace available f(' r expansion.

70 73 Amateur Radio Today · January 1997

consumcrs poin t of \lICW the endresult was that you can now listen to

the same CD on eq uipme nt madeby RC A . Sony. Tandy. or any otherof several dozen diffe rent man ufac­turers, W hen you bought yourequ ip ment yo u d idn' t have tochoo se betwee n a RCA player anddisc for mat or a So ny player anddi sc formal. We were not so luckywhen it ca me to other areas of homee lectronics .

Of cou rse . VCRs come 10 mind .When these dev ices Fi rst hit themar ke t they came in IwO Fl avors :VHS and Beta . Afte r years of bat ­tli ng. V HS finall y wo n and the Beta

, format wen t thc way of eight-trackplayers. Those peop le who hackedthe Beta forma l were the h ig losers.as they en ded li p wi th mach ines thatno lon ge r have tapes uvui lublc forthem.

Another area that still suffe rsfrom a serio us lack of stnndardi za­tion is thai of the AC-IO -DC powersupplies thai arc used wi th con­sumer elec tro nics equip ment . Thesesup plies can be fou nd in an )' volt agethat is a mult iple o f 1.5 vu lts. fro m1.5 to 13.5 volt s , Furth ermore, thereare numerous di ffe rent styles and

Fig , 4 _ The mosf straightforward method of integmling f1 \'OI/(lxe regulator into CI basicpower adopter circuit,

Nn

VIRegulatorVI o VO

vr-, C I

T he packa ging d esign : Option # 1

Dnn ' f blow a fuse!

In most cases you will ha ve 10

fo rgo a ny type o f heal sink on thereg ula to r if yo u choose 10 ret urn theadapt er to its o ri g ina l e nclos ure,Beca use o f th is , the maxim um c ur­re nt a va i la ble fro m a 78 xx device inth is ap plica tion sho uld he cons id­e red 10 he only a bout 25% to 50% o fthe de vice 's max im um rated c ur­rent . This is a pri ce yo u pay fo rhu vi ng a wa ll ada pte r with a we ll­reg ula ted o ut put voltage .

Besid e!"> the reg ulator a nd e xt racaps, yo u might conside r placingano ther it em insi de the poweradapter 's e nclosure- a fuse . By fus­ing the in put side of the regulatoryo u will protect the reg ulator, aswe ll as yo ur project , from an ove r­c urre n t sit uatio n. Ke ep in mind .ho we ver, that th is fuse will mostlike ly be placed inside the ada pter 'se ncl o sure , so to change the fuseyo u ' ll need to take the e ncl os ureapart . Th is mi ght no t he a n eas ytas k.

Packagin g addi t io nal e lectron icsinto a n ex isti ng po wer adapte r is thekey to a well -regulated sup ply thatst ill looks pro fessional. T his iso fte n a n uph ill ba il ie . becauseman ufac ture rs sa ve money by mini­mi zin g the a mou nt o f wasted {i.e .a va ilable) spac e inside e nclosures .

Howe ver, ope ning the powe radapte r witho ut damaging the e n­c losure is ge nerall y the harde st parto f an y modi fica tion project. Too pe n most adapters you ' l! need tousc a sha rp, thin kni fe or ra zorblade 10 cu t a lo ng the sea m betweenthe face pla te (the part with the tcr­min a ls that pl ug into the outlet) a ndthe re st o f the enclosure (the square

bo wl) . If you ha ve yet 10 purchase73 Amateur Radio Today · January 1997 71

JI

AC Plug

is the co mmo n (gro und ) line sharedbetween the inpu t and outp ut pins .Finall y, pin 3 is the output l ine ,whi c h distributes the regulatedvoltage .

II is it simp le matter 10 inco rpo­rare a 78xx se ries reg ulator in to thebasi c power adapte r design j ust de­sc ribed . creating a wa ll adapte r witha well regufured ou tput Fi2 .,• . • AC signa l changes di rec tion.inputsho ws how th is is done . The smaller caps arc used 10 fil ler

The power adapter you sian with out high -freque ncy noise , since theywill need 10 ha ve a n outp ut volt age . tend 10 look like short to ground tobefore mod ific atio n. of a bou t J to 5 high-freque ncy signals .vo lts h igher than the regula ted vo ll -age you ' ll lik e to achie ve. This rc - Don "t lose yo ur coo l!qui rcm ent IS imposed hy the78-se rie s regu lato rs, whi ch need 10 While it is easy to desi gn a 78xx

sec the higher vo ltage in o rder to de vice into a n adapter c irc uit. he re 's

regulate properl y. If you refer aga in a stro ng word of cau tio n abou t th e

10 Tahle I you ' ll see th ai th is amount o f curre nt the se regul ators

should not be a prob lem. as most can supply : T be c urre n t va lue s

adapters output a highe r vo ltage listed in Ta b le 2 repre sent the ma xi-

tha n spec ified o n the ir la bel s. mum amount of CUTTe nt that can be

Besides the regulator itself, only a suppl ied whe n the y a rc mou nted so

few addi tional capacitors are needed to that the y have adequate cool ing. In

fil ter both the input and output voltages. o rder to obtain "adeq uate coo ling,"

The large caps arc used to "smooth out" you must gene rall y usc some fo rm

the voltage produced by the full-wave of heat si nk 10 hel p d issi pate the

rectifier. storing energy for when the heat ge nerated by the regulator.

Output OutputPart Number Package Style

Voltage Cur rent

+5 100mA 78L05 TO·92

+5 1A 7805 TO·220

+6 1A 7806 TO-220

+8 100mA 78L08 TO·92

+8 1A 7808 TO-220

+12 100mA 78L12 TO-92

+12 1A 7812 TO·220

+15 100mA 78L1 5 TO·92

+15 1A 7815 TO-220

+18 1A 7818 TO-220

+24 1A 7824 TO·220Table 2. COII/IIIOIl volues of the 78-.I"uie .l" of voltage regulators , The "Uutpnt Current " CO/-mllll lis ts the maximum cllrrelll for a device mounted on a l lljJiciem/y s;:.ec/ hem sink. UsableCllrrem for the application described ill the test is significamtv less ,

Fig. 5. One way to pa ckage a regulator and extra filler capacitors into a power adapter 'senclosure.

dropped onto a hard floor.Once you modify an adapter, run

it for a while with the en closure justtaped together, not permanentlysealed. Every 15 to 20 minutes ofoperation under full load , open theenc los ure just to make certa in youdon 't have the overheating problemmentioned above .

When you 've finished your modi ­fi cations and tests , reseal the enclo­sure using Super Gl uet or someother form of adhesive that workswcll on plasti cs .

Never modify an adapter ratcd foroutdoor use , even if you plan to useit only indoors. It 's too hard to re ­seal the en closure in a way that isguaranteed to keep moisture out.Besides , if an yone else were to usethe adapter they might see that it'slabeled for outdoor applications ,and use it as such.

The packaging design: Option #2

There is another packaging option ifyou are unable to modify an existingadapter case as described above-youcan purchase a new case. Many elec­tronics supply companies sell appropri­ate small enclosures. Some even selldedicated "wall transformer enclo­sures." These are small cases with elec­trical terminals protruding through themthat can plug into any standard 120Vwall outlet. On the inside of the enclo­sure, you can generally solder to the ter­minals, making connection to thisproject's PC board easy.

If you arc interested in this option,check your mail-order parts supplier fordifferent enclosure designs and sizesbefore you begin the project. Most such­cases arc very inexpensive, and youmight find them a bargain if you findit difficult to open an existing walltransformer case. m

CaseD4

Top View

Outputci OJ 02 0 3

AdhJCap

AdhJRegulator

an adapter for modificati on , try toget one that is held together byscrews. Keep in mind that thescrews ma y not be visible ; they maybe covered by the manufacturer 'slabel , requirin g you to hunt for themby lightl y runn ing your fingernailover the label.

Packing a regulator and additionalcomponents into an encl os ure ismore of an art than a sci ence, sothere is no single reci pe for success,but here are some sugg estio ns : Forthe additi onal compo nents you needto add into a circuit, try to place asmany as possible di rectly on theadap ter ' s printed circuit board(PCB). Th is fo rm of mounting tendsto increase the circui t's reliability.

In some cases, space permitting,you may be able to moun t somecompo nents o n the bottom of thePCB. This is especiall y true ofsmaller items, like filter caps .

Somet imes there arc small metalplates mounted inside adapters forvarious reasons . You can often usethi s metal plate as a heat sink forthe voltage reg ulator. This will in­crease the amount of cur rent youcan safely draw from the devi ce.Make sure the plate is not elec tri­cally connected to other parts of thecirc uit.

Be sure to use heat-shrink tubin gor tightly-wrapped tape around anycomponent leads inside the enclo­sure . The leads may not be in dan­ger of short ing together now, butcomponents might shift around con­siderably the fir st tim e the unit is

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Number 74 on your~bKIc u rd

A Hamfest ComputerShopping Guide

You can computerize your ham shack f or pennies on the dollar ifyouknow how to shop the hamfests .

Alex Piechocki N3JSU15 Locust Avenue

Towanda PA 18848

Wlh hamfests and computer­fests merging. they're gellingto be great places to shop for

computers. Today there is so much qualitycomputing equipment available at suchcheap prices that no one bas the excuse notto have several computers in the shad. ln­deed. today's bamfests often ha..e morecomputer than ham equipment exhibitors.

IBM and compatibles with up to a 286processor are available for under SI00.complete and working. And that's with acolor monitor. keyboard. disk drives. andup to a 20Mh hard drive. There is a tTC­mcndous supply of these machines. andlittle demand, so they' re cheap. Theymake great packet stations. and will runsatellite tracking software and do wordprecessing: they' re a great learning tool.Businesses sell their old computers for al­most nothing to avoid hazardous wastedisposal fees. as demanded by the EPA.Some of them are kaput. but many arc justolder. slower models which have had to bereplaced.

What to look ror

First. you want a monitor without aburned-in screen. Next, look at the coolingfan. If it is humed out or wadded up withfi lth. stay away! Keyboards should also beclean. right down to between the keys. Aquick cleanup to cover up years of abusewon't usually get between the keys. Also.the case itself should he reasonahly clean.Look for telltale signs of neglect fromdamp, unheated storage- like rust!

Open up the case and take a look in­side. 'Ibc motherboard (the largest primed

74 73 Amateur Radio Today · January 1997

circuit board you can see) should be clean.with no dirt buildup or corrosion. Checkthe battery. If it ha... leaked and corrodedthe surrounding chips and wire traces. youdon't want the misery.

Check the cards plugged into themotherboard. The connectors should con­form to the ISA (Industry Standard Archi­tecture). That means you should have a62-pin connector next to the back of thecomputer for connecting 10 the 8-hit bus.

"The dealer has already madehis profit, so any money hegets from the sale of theseused drives is pure gravy."

Next to the 62-pin connector should be a36-pin connector. This connector. alongwith the 62·pin one. arc used to attachcards (0 (he l6-bit bus. Some manufac tur­en; used custom connectors so their cus­tomers would have to buy their customcanis. Avoid these computers.

The AT&T-6300 has the l6-bit bus onthe other side of the motherboard! IBMPS/2 models 50 and higher have a custombus referred to as MCA, or microcharmel .Parts for these guys are few and far be­tween, and thus arc expensive relative tostandard ISA boards. The IBM PC Junioris in a class by itself. as are all Apples. Theinstalled canis tell you a lot about whatyou are getting. Typically on these low­end machines you will have a minimum ofthree cards. One for the monitor. one forthe disk drives. and one for input and

output. If thcrc are more. you might be get­ting a memory upgrade or a turbo proces­sor. All of the chip" have their date ofmanufacture on them. typically the yearand week. This can indicate if some of (hecanis were added later or if everything isoriginal.

Memory is important. The PC and XTcomputers. with the 808018086 micropro­cessors, could only handle 6-IOK ofmemory. The 286 machines could addressup to 16Mb. It is very easy to tell howmueh memory you have by checking thechips on the motherboard. Fi nd a sectionof identical chips; the older machines hadtwo banks of eight chips each of the 256K(total of SI2K) and two bank s of 64Kchip.. (128K). After the manufacturersidentification number there will be a 64.256 or 1028, followed by a da..h and thenthe speed that these chips can handlc. Allyou need to do to the speed number is toadd a zero and you have the speed in nano­seconds. For example. a -15 is 150 ns: a-7is 70 ns. Speed is important because thefa..tcr the motherboard clock's speed, the

Jaster the memory needs to be. If you arerunning an 8086 at a typical 4.77 MHz.your memory needs to be at lea..t 2m ns.For a 50 MHz system the speed of thememory increases to 40 ns. You also willsec that the 64K and 256K chips have 16pins on them, the 1Mb (1024K) will have18.

The 286 machines started to usememory called SIPs (Single In-line Pack­age). This memory had the chips solderedon a small printed circuit hoard that had 30small in-line pins. The chips used on these

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technologies; as soon as Super VGA be- ,came available, the installed VGA moni­tors became obsolete. Also, manycompanies lease computers, and at theend of the lease there is a lot of outdatedequipment to be dumped. RefurbishedVGA monitors can be bought for around$ 100 and come in several sizes. I' ve seena 12" go for under $75, and the IS" go for$ 130. Try to purchase brands that you willbe able to repair. Schematics on somemonitors are harder than others to find.Some schematics arc included with thedeal, whi le others might cost you over$50! With any monitor you need a com­patible interface card to run it. CGA andEGA cards can be bought for under $ 15.VGAs, on the other hand, start where theless expensive canis leave off. There's alot of snob appeal in these cards, so brandnames like Orchid and Cirrus (end to in­crease the a<;king price as well a'i the

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copy! Unfortunately, to make good use ofthe version 5.0. you need a lor of memoryand at least a 386 processor.

Documentation is helpful when itcomes to setting some of themotherboard's j umpers. If you arc plan­ning on doing a lot of tinkering and wouldlike 10 modify the motherboard, there ishope. Some of the larger libraries have, intheir technical section, a book copy oreven a CD-ROM of The Micro House En­cyclopedia of Main Boards. This refer­ence book dctails all of the switches andjumpers on most of the motherboards youwill find.

Upgrades and parts for your PC

Because used computers bring suchlow prices, many dealers run chop-shopoperations. TIley disassemble hundreds ofPCs and bring the parts to flea markets inhopes of making a larger profit. You canget an idea of pricing by checki ng thecJassifieds in some o f the compu termagazmes.

The first monitors were black and whi te(or orange or green) and used an internalMDA (Monochrome Display Adaptcr)card. TIley were only good. for text. Thenext monitors were called CGAs, after theinternal p lug-in card (Color GraphicsAdapter) . This improved somewhat withthe next generation called EGA (En­hanced). the color monitors truly made animportant transition when they went toVGA (Video Graphic Array). Hospita lsand some ind ustries keep up on the latest

memory boards can be easily removedwith some solder wick and a small solder­ing iron. They can then he transformedinto SIMMs (Sing le In-line MemoryModule), which most new computers usetoday. A vendor might be se llingrnotherboanis for $3 each, untested withmemory chips still installed; these boardsarc worth buying just for the memory! Ionce bought 486 motherboards for $10each just for the parts. On each board was256K in cache memory in sockets, whichmade it easy to remove them. Cachememory, and video memory, are differentanimals than regular computer memory.

1bc computer 's mai n memory is re­ferred to a DRAM, dynamic random ac­cess. This memory is nothing more thantransistor and capacitor pairs. 1bcy aredynamic in the sense that the capacitor al­ways wants 10discharge, so the computerhas to ensure they get charged back upmillions of times per second . SRAM(static RAM) or VRAM (video RAM) orSCRAM (static cache RAM ) arc all thesame idea. They arc set to d igital ones andzeros and stay at this value until exter­nally changed. They are very fast, largelydue to more transistors inside for themegabytes they contain, and more expen­sive, hence you will not sec manycomputers using these for main memory.

Software and documentation are an im­portant part of the deal. "No software"can mean having a computer that can' t doanything. All computers have a smallsoftware progmurn bu ill into them. Theprogram executes whenever you tum onyour computer. It is referred to ali thePOST (Powcr On Self Test) . This se lf di ­agnostic will ind icate any nu mber ofproblems, from a stuc k key on the key­board to bad memory. But after this themost important software to have is theOOS (Disk O perating System). Fortu­nately, if your computer is really barebones, down the isle is probably someonewho will sell you an obsolete copy for acouple of dollars. PC: OOS or MS DOSarc the same softwarc-one was writtenfor mM, and the other was written formM compatibles . Both were written byMicrosoft. TIle program has undergoneseveral revisions, with the current one upto version 6.2. Tbe older computers can­not even usc the newest version, so thecopy of version 3.2 for one or two dollarsisn't too bad a deal . Version 5.0, which isvery close (0 the latest and greatest fornewer machines, can he had for $5 a

quali ty of documentation and thcquantity of memory, Since VGA cardscan still he bought new for under $50.it pays to keep up with the latest ads .The latest and thc greatest is to heable to plug your video card into thehigh-speed computer bus. Th is onlyexists on 486 and newer compute rs. Itis referred to as the Local Bus, YESAlocal bus. ami PCI bus. T his is whatyou eventually wou ld want to gradu­ate to if you have the latest fast-actionvideo games to play. If you like a lotof color resolution. selec t a video cardwi th ur least I megabyte of videoRAM . The one really neal thing aboutall of these cards is that they are alldownward co mpatible: in otherwords. the software that runs on your~DA system will display correctly onCGA. EGA and YGA systems!

Disk dri ves come in several flavors.The Iloppy drive on the PC was only ca­pable of storing 360K worth of data,The XT had a version with two Floppies:one was a 360K and the other a 1.2Mh,The crazy thing about these was that themagnetic media on the disks were d if­ferent for each of the disks. That madefor easy mistakes in using them in thewrong drive. Therefore you could endup with read or write errors. eventhough the disk drive was working fine.These large 5.25" dri ves gave way 10

the 3.5" 720 Ks. which arc basically usc­less today. The standard 3.5", which ison all new machines, prov ides 1.44Mb.The small 360K drives are available

new for $1 . so you don' t repair these.you just throw them out whenever theyfail! The large 1.2Mhs arc available for$20 used. and the small I.+tMbs youcan buy for under $30. Most floppydrives plug in via a flat cable to thesame driver card as the hard drive. Thenumber one wire is painted red, so makesure it plugs into the number one pin onthe drive. If you arc running only onedrive. the end of the line plug is used. Itis the one with the twisted piece ofcable next to the connector. This "end"piece is the A drive when you have twofloppy drives installed.

Hard drives arc a lot of fun. There aremany wacky ones out there waiting foryou! The earlier ones included on thePC were of the MFM (Modified Fre­qucncy Modulation ) type. Followingthese were the RLL and the ESDI. bothimprovements to the MFM techni que.76 73 Amateur Radio Today . January 1997

Tbcse dri ves require special formattingto use so removing an MFf\.1 drive froma PC and installing it into an AT re­quires a comple te new format! We'retalking machine code here. which is not apleasant task for a novice. Stay away fromthese old outdated formats unless [hedrive is exactly the same as the one youhave and you've grown attached to irsquirks.

The latest and greatest today is SCSI(Small Computer System Interface) andIDE (Integrated Disk Electronics). Theyboth are about the same speed. One sendsits data in parallel and can support up toseven devices (SCSI). while the other(IDE) sends its data in serial and can sup­port two devices with the same interfacecard. I recommend going with IDE, ; theyinstall more easily than MFMs and RLLs.They plug into the IDE interface card.which is also plentiful and chcup-c-typi­cally one or two dollars. New ones can hebought for under $20. IDE drives of

"A vendor might be sellingmotherboards for $3 each ,

untested, with memory chipsstill installed; these boards

are worth buyingjust for thememory!"

40Mb can he bought for 520 from dealerswho upgrade computers. The dealer hasalready made his profit. so any money hegets from the 5.11e of these used drives ispure gravy. Hard drives are hermeticallyscaled and designed for so.om or morehours of use before failure; however,sbock. vibration and heat can lower tbar.But there should still be many hours leftfor you to play with.

Accessories such a" CD ROMs. soundcards and such are available us people up­grade. Single-speed CD ROMs with 8-bilplug-in cards are available new for $25.There's no demand for these when thestate of the art is already selling CDROMs at 8X speeds. People are condi­tioned 10 think that single-spin is too slow.Believe mc-a single-spin CD player willstill locate that callsign for you faster thanusing the hook. and you have the addedbenefit of playing your favorite musicalCDs too. Sound cards arc available aspeople upgrade to the latest and greatestin multiple voice polyphony. After years

of listening to single sideband, an 8­hit sound card will sound heavenly.But don' t "top here-16 bits is thestandard, and again, if you shoparound you can find these at bargainbasement prices.

Ruilding your own computer

Over $ 10 billion in hardware is outthere gelling obsolete. Some of it willlind its way to your local hamfests forpennies on the dollar. What a tempta­tion to build a system that is reallyunique. teaches you a new ...kill. anddocs something useful for you aroundthe house or shack.

Remember , with computers runningin the RF runge you need good ground­ing. If your enclosure has sturdygrounding fi ngers. along with liberalamounts of stainless steel \.\.'001 on theedges, thcn when you trunxnut your RFwill not get into the computer and con­fuse it or shut it down. This will alsokeep the computer from messing upyour rcccrvers.

Tbc best way to build your own is tostart out with a cheap system. The 286computers came with good power sup­plies. Be very wary of the high volumecomputers such a." IBM, Del l. Compaq.and AT&T, since only large companiescan afford to build nonstandard. one-of­a-kind parts. Almost all of thc othercomputers usc generic parts.

Most power supplies arc identical.They arc all switching supplies, andeven the connectors to the motherboard

arc the same. Just remember to put thefour black ground wires in the middle ifyour supply has IWO plugs.

Tbc one thing to pay attention (0 iswalls. The very early computers weresmall; only g5 walls. Try for somethingup in the 250-wall or more runge. Ac­cessorie... take IOl<; of power. Once youhave a computer with a good powersupply. case and disk drives. all youneed is 10 replace the motherboard andyou can say you bu ilt your 0\\0'0.

Motherboards are relati vely incxpcn­sivc. even if you buy a new one. Newmotherboards are rested and warruntied .

and go for $50 or less for a .t~ type.You can buy these l10anls minus theprocessor chip, which is the big money.Look around at the . fcsrs for processors.Since many people upgrade. you canfind 486-SX 25 fl.IH J.: processors for

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game port, and fax modem cards in. Thereis a good chance that the computer is try­ing to talk to two or more cards at once.Computers may be fast. but they still needto communicate to the input and outputone at a time.

This has been a whirlwind tour of com­puters, by no means complete. Even ifyou are planning to purchase new. goingto the dealer with some basic knowledgeof computers and the prices of the variouscomponents can help you drive a betterbargain. I hope I will be seeing you at theflea markets, having as much fun as Ido, recycling computers and kccpi~

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the motherboard for these chips, dividethe chip frequency by its multiplyingnumber. The DXl4-IOO is run at 25 MHz;the DXI2-66 at 33 MHl.. After everythingis put together it is amazing how thesesystems start right up.

Digital electronics does not have all ofthe tweaking that analog docs, but therewi ll be some small details to attend to be­fore you will be on your way. Allmotherboards have some fonn of setup.The earlier boards used jumpers. Thisevolved to software disks. to the pointnow where the setup is part of thesystem's BIOS (Basic Input Output Sys­tem). Remember those POST error sig­nals (beeps son of like Morse code, or anon-screen message to tell you your error)?

When you start up you have the oppor­tunity to go into the computer's CMOSsetup. This is a couple of chips that uscvery little power and have the on-boardbattery feeding them when you tum offthe computer. When you go into the setupyou tell the computer what you have at­tached to it. You type in the size diskdrives that you installed, the amount ofmemory on the board, what functions youwant the motherboard to use, such asclock speed, cache controller, etc. You canusually wing it, bUI having some docu­mentation on what and how sure makeyou feel IOOre comfortable as you arctyping.

Sometimes your system may appear tobe dead on startup. The boards you in­stalled might be set 10 the same address orinterrupt (IRQ). Simply remove all of thecards, with the exception of the video one,and gradually start putting them back untilyou find the conflict. This type of problemdoesn't usually happen until you put theCD- ROM, sound card, mouse driver card,

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73 Amateur Radio Today - January 1997 n

$20 10 $30. That is the bargain way tostart. You can always upgrade with thefaster DX-2s, 3s and 4s later.

First, you should be aware of how theseprocessor chips are different. All Intel 486chips are made the same. It is in the lest­ing that they are given their labels. TheSX label is for 486s (hat had defectivemath coprocessors, which are for floatingpoint math. Tbe only programs (hat use itarc engineering work stations, computerassisted design (CAD), and some spread­sheet programs. Most games don' t usethis processor since they don't need theprecision or the resulting slower execu­tion speed. To upgrade the SX with a mathcoprocessor you have to buy a 487 chip.This chip is a OX chip with an extra pinon it to disable the SX chip (pretty sneaky,eh?). 1be 486.'1 are warmed up and run at ahigh clock speed at the factory; the onesthat pass error-free get the highest ratings.lbc ones thai fai l are re-tested at a slowerspeed. Thus you have your DX-SO MHt:,DX-33 MHz, DX-25 MHz, etc. The sameholds for SX too.

Some motherboards let you changetheir clock speed with little jumpers, somewith software, and some need to have theon-board clock chip replaced. Make sureyour motherboard can run at the speed ofyour chip. If you only run your computerfor a short time, or slap a big heat sink andfan on the chip, you canjuice up the clockspeed and run faster than the numberspainted on the chip. I've run my 25 MHzchips at 33 MHz with no errors. Just pUIyour fi nger on the chip under load ... if itfeels hoi you will shorten its life , but if itis cool 10 the [Ouch you shouldn't haveany problems. The DX12 series plug intothe same socket as the other 486.'1. It isworth it to pay a few dollars extra for aZIF (Zero Insertion Perce) socket. Tbenyou can change your processor with no ef­fort in seconds. l ust remember, there is analignment dot that needs to be followed.Sometimes it is a squared off comer, sofollow it to ensure you put the processorin the right way.

The OX12 and !3 and /4 all have fre­quency doubling, tripling, or quadruplingcircuits in them. The reason it makes yoursystem faster is that when an instruction issent to the processor, the processor cantake many clock cycles to decode and acton the command. But it only takes onecycle to bring in instructions from themotherboard. So, to set the frequency on

Number 78 " " y,",r FHdDM:1r. card

A Retiree's HF Mobile InstallationThis style of hamming ain 't exactly hard to take .

Bert Simon K2FZ2110 NW 45th Ave.

Coconut Creek FL 33066

Afte r having lived on boats for15 years, the concept o f a mo­bile HF installation was so em­

bedded in my failing brai n that whenthe lime came to give up boats and be­come a land lubber, I knew that thedreaded ham virus would force me toacquire a good HF mobile station. Sell ­ing my boat pUI me in a position tochoose. within reason (my wife said itwas OK), the vehicle, the radio and theantenna .

The vehicle

I env isio ned a ve hicle that would con­tain a small desk for writing. readingand hamming , A comfortable place torecl ine wou ld he kind of nice, for rest­ing the eyes when the need arose (whichhappens rather frequently as o ne nearsthe QCWA second cluster category). I

PholtJ A . Inside the \"{In.

78 73 Amaleur Radio Today -January 1997

chose a "high-top conversion" type vanwhich came complete with fourcapta in's chairs and a bench seal thatfolds down 10 bec ome a bed at the nipo f a switch. A sturdy desk was installed

"The marine channels mightcome in handy if I'm ever

maroolled by a rising tide."

behind the driver's posit ion and voila! Avery comfortable vehicle where every daycan he a "Field Day." Three additionalbatteries. of the gel cell persuasion, wereinstalled. along with battery safety/dis­connect circuit breakers.A digital voltmc­ter is being constructed to provide closevoltage measurements. important in mak­ing a battery's life long and prosperous.Additionally. a through-the-ceiling fan

was installed and is generally in operationwhen the van is parked. I haven 't found itnec essary 10 charge the batteries afterIhTl'C hours of hamming and ventilating,hut then again. so far I haven't operatedmorc than three hours at a stretch.

T he radio

The latest breakthrough in HF com­mun ications appears to he DSP (digita lsignal processing) in which, due to thewonders of science, the gcrshmcckdasignals go through an amorphous trunsl­tion into a dig ital cong lomeration co m­plctcl y alien to humans. It is thenmagica lly transformed back into sup­posedly intellig ible signa ls. Consider­ing that thi s radio might I1c my last bigham purchase before being recalledfrom this planet. I decided I might be re­miss if I didn 't become a DSPer. O therconsiderations involved money as wellas the weight o f the rad io (some o f thevery sophistic a ted radios weigh in at3(}..plus pounds and get into the three­plus kilobuck category). I decided itwould be best 10 keep the "radio foot­print" to a minimum and so decided o na remotely-operated ri g.

T he radio which met my criteria wasthe SG 20m with Po wcrtalk head (DSP,that is ), made by SGC of Bellevue,Washington . The price was under threekilobucks and the rad io weighed 12po unds. which d idn 't make any differ­ence since the remote head, which wasthe device to be table-mounted. wasonly about two pounds. This radio has

"If I didn 't require a stool to stand on, I could probably installthe antenna in less than a minute."

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73 Amateur Radio Today· January 1997 79

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I have found Don Johnson's book onHF mobile installations to be a wealthof information. Additionally, valuablemobile an tenna comparisons are con­tained in QST and Worldradio issues.The "HF Mobile Shoot-Out" describedby Worldradio compares the relative ra­diation of 17 HF antennas rangi ng fromthose having center-loading coils withand without top hats to the SOC·QMS(20 dB advantage) bottom- loaded an­tenna. The high Q center-loaded typewon hands down, with those having tophat devices showing a 2 or 3 dB advan­tage over the less grotesque center load­ers . The worst antenna was the onewhich was advertised as "the 20 dB ad­vantage." It measured about to dB lessthan the typical center-loader. QuotingGilbert and Sullivan: "Things arc sel­dom as they seem." My advice: Bewareof extravagant claims.

I had decided that an antenna thatcould be remotely tuned to continuouslycover the entire 80 through 10 meterspectru m and have a high Q center­loaded coil would be my choice. I in­vestigated two of the se veral companiesproduc ing such antennas : T.J. AntennaCo. of Hermiston, Oregon, and High

The antenna

Now, with all my criticism regardingthe SOC 2000, one might think that Idon't like it. Au contraire, mon ami. Theradio, in spite of its faults, does have itscharm, although I do believe that it,along with SGC's QMS mobile antennaand its "20 dB advantage," wou ld bebest su ited for a non-technical/non-hamparamilitary-type operator.

per hour. In fact, in my degenerativeconditio n I find it some what exasper­ating to locate the necessary buttons(let alone execute them) before thetelltale sound of the beeper announcesthat the fou r-seco nd period is up and Im ust start over again. (Perhaps a ncu­ron transducer can be added to ac tiovate my sale operat ing brain neuron ,which might enable it to move fastenough to avoid the dreaded four-secondannouncement.)

requirements. But heed these words ofcaution: This radio is not for every hamand there are those who may find someof the operating features are less thanideal for typical amateur opera tion-ifone allows four seconds to go by with­out using the main frequency dial it isthen necessary to press the "FREQ"button, sometimes more than twice.When this button is pressed, the radiobeeps to announce that the butto n hasbeen pressed and the tuning knob isnow operational; it' s not exactly a "con­test" radio . As for CW, I have found itunusable due to the delay of the AGCresponse. I have di scussed th is problemwith SGC and am awaiting their recom­mendations. For now, I am able to usethe radio on CW by providing an MFJkeyer with an audio tone, and then feed­ing the tone signal plus an additionalpair of leads to a big old-fashio nedswitch. Both sets of leads are wired to aseparate microphone connec tor. Theother item which takes a bit of gettingused to is the CW DSP operation. Theapparent bandwidth in this mode is verysharp and in order to be able to switchthe DSPer fro m the broad mode to thesharp mode it is important to receive theCW tone at approximate ly 1000 cps . Ifind that I'm not always able to selectthe lone accurately enough to fall withinthe passband of the fi Iter. Again, it' s notexactly a contest radio.

There are approximately 30 push­butto n funct ions to this radio and theDSP version has an addi tional eightpush-buttons plus some added knobs.I ad mit it would take a beuer man thanI to operate this radio and st ill survivebebopping down the road at 65 mi les

nice features, such as over 600 marinechannels programmed into its memory.I figured this might come in handy ifI'm ever marooned by a rising tide-c-Ican always call the Coast Guard. Theradio also comes with over 60 ham fre­quencies programmed, which mainlyrepresents the band edges as well asother convenient frequencies used forham mobile/marine operations . Addi­tionally, 60 other frequencies may beprogrammed in according to individual

next to the condo, as compared to thecondo base sta tion. A good indicationof the mobile's performance is theamount of returns I get from callsmade; it ' s much better than that of mybase station. The antenna tuning is re­mote ly controlled by an up/downswitch conveniently installed near theradio and the buil t-i n SWR indicationof the SO 2000 works well, althoughit docs require the pressing of twobuttons to activate the SWR function.The "SHfT FUNC" button must bepressed before you can press the"FWD-SWR" button. I wouldn ' t rec­ommend tuning the an tenna whiledriving-however, the usable band­width on 20 meters is quite adequate,about 200 kHz without requiring re­tuning . I attri bute the success of mymobile insta llation mainly to the qual ­ity of the High Sierra Antenna and thesage advice in Don Johnson 's book. Imust also give credit to SOC becauseI have frequently been told that I haveexcellent audio quali ty.

Life is good. II

The end result

I was able to mount the anten nawithout drilling any holes in the vanby using U-bolts to fasten the a lumi ­num structure to the spare tire sup­ports. I recommend using proper HFpractice and making certain that thereare good grounds between the sup­porting structure and the vehicle, butthen again, just follow Don Johnson 'sadvice and you' ll have a good instal­la tion. Truthfully, I am not absolutelycertain how my signal would be af­fected without the proper grounds, butI' ll put it in the same category as thetest for pearls: "Place the pearl in acontainer of vinegar and if it dissolvesit was real. " T he only holes 1drilled inthe van were the ones to provide theDC voltage and the coax feed to theantenna; I thought it looked betterthan having wires dangling in thewind whenever the antenna was not inplace.

One other advantage of this rad ioand antenna combination is its abilityto tune in all kinds of other HF act ivi­ties- SWL broadcasts, marine stuff,etc. Having a continu-ously tunable high Q an­tenna coveri ng all thefrequencies from 80through 10 meters reallymakes for excellentreception .

I am thrilled with theentire mobile operation. Icompare it to my basesta tion, which is anICOM 735 using anICOM AH-2 remotely­operated an tenna tuner.This particular setup ismy condo HF station andemploys about 17 feet ofwire as the antenna plusabout five radials, in­stalled under the carpetof the ham shack, whichrange fro m five to 10fee t-not a very good in­stallation but at least it'shidden from the eyes ofthe condo commandos . Ifind that I am able to re­ceive more signals andmore OX from my mo­bile when parked right Photo B. K2FZ's van, with the antenna attached.

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tenna Co. of Hermiston, Oregon, andHigh Sierra Antennas of Nevada City,California. They appeared to havesimilar products, all based on the DonJohnson design. I chose High Sierrabecause they had available a type ofmount which allowed the antenna tobe readily removed. In fact, 1 can re­move and/or install the antenna in lessthan three minutes, but if! were as tallas a basketball player and didn' t re­qu ire a stool to stand on, 1 probablycould do it in less than a minute .

High Sierra makes several types ofmounts and they can also manufacturejust about any mount to suit individualrequirements. Their mounts arc ofheavy-gauge steel construction and areattractively painted black, whichclosely matches the type of rcctangularalu minum extrusions used in condo"screened-in constructions." I decidedto use High Sierra's mount and join it toa two- by three-inch aluminum extru­sion (readi ly available at large hardwarestores). 1joined the aluminum extrusionand the "Universal Mount" from HighSierra with #14 SS self-tapping screwsand star washers which provided rigid­ity and good electrical bonding.

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The largest organ in our bodies is ourlungs, and they' re there 10 bring oxygen intoour systems. We bum oxygen for fuel. Plus,more oxygen in our blood hel ps kill off mi­crobes and viruses. Now do you suppose thatthere's any connection between the droppingpercentage of oxygen in our air and the re­cent increase in all kinds of illnesses? Itmight even tie in with the increase in gut­lessness and lack of creativity shown by ouryounger generat ion since oxygen is criticalto the brain's operation.

How much oxyge n have we lost so far? Acouple hundred years ago our air had 38%oxygen. In the 1950s it was do wn to 21%,and now it's down to just over 19%! Worse ,in the cities it's as low as 9%, due to the ex­tensive heating of buildings by burning fos­sil fuels, the thousands of cars and trucks,and even mill ions of people breathing.

One of the benefits of jogging is thai itforces us to breathe more heavily and bringin more oxygen. Dr. Douglass, of SecondOpinion, has a great book out on how to pre­vent aging . In it he recommends breathingpure oxygen every day while exercising as away to reverse the aging process. Adding

Continued on page 82

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nation, under God" stuff. Hmm, now that Ithink about it, that "Under God" pari gotadded later. OUf pledge of allegiance when Iwent to school never mentioned any dei ty.

For that mat ter; the pledge never meantanything either. If the United Slates wasviewed as good we'd support it. Consideringthe problems we face today, it is gettingmore and more di fficult to feel anythingstrong about our country. The main thing ithas going for it is that , as te rrih le as thingsare, they seem 10 he worse most other places.But that' s not something I'd will ingly laymy life down for. If you don 't chew gum,spit on the street, spray- paint cars, or pee inelevators, Singapore has a 101going for it.

During WWII I had no problem in volun­teering for the most dangerous duty therewas because I rea lly didn' t care muchwhether I lived or died. Recent research hasshown, as I've mentioned, that th is was theresult of the child hood beatings by my fa­ther. Thi s is one of the major causes fo r tee nsuicides. Luckily I underwent some brain re­pairs when I was 28 which got rid o f all thatcrud and changed my life.

Please, let's stop zealots from tryi ng 10 usethe government (and our fede ral judges) tofurther their religious goals. I'd also like toget the government out of social engineeringtoo. Not one program has worked, but that's

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The Value of College

If you've read anything aboutbreathing you know that just as wegradually lose the flexibility of oureyes from focusing them at onedistance or direction so much ofthe time---reading, computering,TV watching- we also lose agreat deal of our lungs' capacity tobring oxygen into our bodies byshallow breathing. Every so oftenexhale completely and then suckin as much air as you can into yourlungs and hold it for a few sec­onds. Then completely exhaleagain. Use more of your lung ca­pacity whenever you think of it.And hyperventilate 10 make up forall that oxygen thai's no longer inyour air,

I see where in Beijing there is aflourishing business in sellingoxygen. They have booths whereyou can breathe 50% oxygen for$6 an hour. That's somethingwhich could do well in our morepolluted cities such as L.A.,Denver, and New York

NEUER SRY DIEContinued from page 81

oxygen to our bodies seems 10help beef up our immune systems.which in tum can help reversearthritis, cancers, and otherannoying breakdowns of the body,

It seems to me thar if you caneven remember every now andmen 10 hyperventilate, that's going10 being more oxygen into yoursystem. But I know how difficuhit is to remember to breathe,

When we gel tense our ten­dency is to hold our breath, mak­ing it even worse. There are fewheadaches mat can't be cleared upby hyperventilating-gellingmore oxygen into your system,where it first goes to your brain,and then to the rest of your body.The brain uses a surprisingamount of oxygen, so when wecut down the brain is one of thefirst parts to malfunction,

TIle decreasing oxygen percent­age in the air means a higher per­centage of nitrogen (and a muchhigher percentage of CO

2) , lead­

ing 10 an increase in nitrogen nar-cosis, the "rapture of the deep" it's A recently released studycalled when you're diving. It' s a showed that the $40,000 invest-gradual loss of reality, but one mem for a college education re-which is not noticeable by the in- suits, on the average, in an 10-

dividual involved. Maybe you've crease in lifetime earnings ofnonced a lot of that going around. $300,000. Hey, that's almost a

82 73 Amateur Radio Today. Janua ry 1997

to-times gain on your investment!No wonder parents are so anxiousto get their kids into college, Yeah,except for one little tiny thing. Ifyou take that same $40,000 andinvest it in something safe that re­turns 6% you'll end up with$550,000.

Big corporations put a gooddeal of stock in your college de­gree when they're hiring, but fewsmall companies give a hoot. Theywant to know what you can do forthem, not where you went toschool. And working for a largecompany is one way to pretty wellassure that you are never going tomake any serious money. I keepmentioning the Inc. magazine sur­vey which showed that virtuallyall of our more successful entre­preneurs either skipped collegeentirely or dropped out in Irusrra­non after a year or IWO . Collegedoes help the unmotivated tomake more in dead end jobs. butseems to be a wassrc of time andmoney for anyone with the deter­mination to succeed. So much forthe election oratory about how ev­eryone should be able to go to col­lege. For what? Just to keep themout of the labor market for fourmore years at public expense andfurther dumb them down anddemotivate them?

I tried hiring RPI graduates formy company and was appalled attheir lack of skills or even any in­terest in acquiring skills. I went tothe university and interviewedgraduates, looking for the mostpromising. Most were incredibleduds and not worth even trying,The few I ended up giving a trywere unmotivatable.

When I started 73 I used to hirecollege dropout hams and leachthem the publishing business, andthey were eager to learn. Somehave gone on to excellent careersas a result, doing very well forthemselves.

Just as anyone with the righthelp can learn 10 read and write ina hundred hours (according to thetop prize-winning New York Stateand New York City teacher JohnGatto), anything of value one canlearn from going to college can belearned in a tiny fraction of thetime by reading books by theworld's top experts (who beat theheck out of the professors mostcolleges provide). Our colleges,like our grammar and highschools, are a mess.

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the change they' d ge t back fro m$3 after buying a 60¢ bowl ofsoup and a $1 .95 sandwich. Par­ents are spending fonunes onfour years of expensive baby-sit­ting, and we' re all forced by lawto support this mess. Or else goto prison.

American students rank. #1 inthe world in how good they feelabout their math skills, but a1992 international study by theEducational Testing Serviceshowed us ranking last in mathachievement (well behindSlovenia). In 1972 28% of col­lege-bound seniors had an A orB high school average . By 1993,83% had an A or B average,while at the same time theirSAT scores .....ere plu mmetin g.No..... the educati onal establish­me nt, to cover its dirty tracks,is planning to "re-norm" theSATs, s ince they've gone downpermanently.

The students with the lowestSAT scores become educationmajors. Students who earn edu­cation degrees have lo wer scoreson al l the accepted tests than anyother major than social work.They don' t read, and few can.....rite a coherent leiter. On theaverage, our teachers read onebook a year, and that's a fictionbook.

More money isn ' t going tocure this mess. Paying dumbed­down teachers more isn' t goingto make them better. Creati ngeven more administrative layersisn't going to help our kids.

Why did you have a kid any­way? Your kids are probably theonly mark you're going to leaveon the world to record your hav ­ing been he re . Why are youteaching them to eat garbage anddrink sewage? Why are you put­ting them into our cesspoolpublic sc hools?

Maybe you've read that para.chial schools cost about a thi rdas much as our public schoolspe r student, and teach them farmore. Probably not.

So what can you do about th ismess? Stan at the heart of it:your government. Get out thereand vote, mak ing sure that youNever Re-elect Anyone (NRA).And get your fami ly and friendsout there to do likewise . Let 'sflu sh that Congressional toiletwe' ve allowed to stop up andstink. Step two is to get some hamfri ends to ron for your state legis­lature and re-elect the heck out ofthem. Let' s infi lt ra te the sys­tern a nd sta rt h ack ing bac k

Continued on page 85

your nose in what a mess you'velet our schools get in . It's badenough that you' re screwing upyou r life with that garbageyou've been eating and se wageyou've been drinking, but in ad­dition to teaching you r childrento eat and drink the same de­structive stuff, you' ve also al­lowed o ur school system to dis­integrate so they are be ing men­tally poisoned and stunted. Hey,don't look around for someoneelse to blame. And none o f thisgee, what can little me do aboutbig problems like that?

Now let's look at so me factsof what you' ve sheepily let hap­pen, and most of it has beendone with the money our be­loved government has taken outof your pocket and spent for you .You can 't name one single jobthe government is doi ng thatcan't be done far better and atless than half the cost.

The government loans for stu­dents have helped zoom collegeCOSIS. $24 billion today, andheaded for $36 billion in fiveyears. All not just a total waste,but a poisoning of the educa­tional wel l. I won't repeat againmy simple plan which wouldcompletely eliminate college tu ­ition and at the same lime cnor­mously improve what stude ntsare learning, making it infinitelymore pract ical and useful in thereal world.

In the past 15 years, while theConsumer Price Index has risen74%, college tuition has risen anaverage of 234%. In 1979 thecost of a college education (301·ready inflated> equaled 2 1% ofthe average family 's income. It ' snow 39%. Ten ured professorsearn an average of 560,000 an­nually for 18 hours a week ofwork, 30 weeks a year.

From 1975 to 1985, while stu­dent enrollment grew 10%, thenon-teaching staff ( like deans)grew by 60%. And in the last 30years the academic year shrankfrom 191 days 101 56.

AI a majority of the top 50colleges listed in US News andWorld Report stude nts cangraduate without taking a singlecourse in math, science, English,history or literature . The HudsonInstitute reports that Americanschools are now awarding moredegrees in home economics thanmath and more in protect ive ser­vices than in all of the physicalsciences.

A fede ral study showed that56.3% of the graduates of four­year colleges cou ldn' t calculate

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Priced at $ 1.074. the OX ­70TH can he used as an all­mode (SSB. C Wo FM . AM , andDala l radio in mobile/base/per­table envi ronme nts. A mobilemount ing bracket is incl uded .and many other accessories a reavailable. See your deale r formo re in fo rm ati o n or w ri teA linco. 4 38 Amapolu Ave.. Stc.130. Torrance CA 9050 I. Phone(3 10) 618-86 16 or FAX (310)

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The new OX-70TH was cre­ated for hams who've enjoyedthe fea tures of Alinco's popularline o f amateur equipme nt, huthave wanted more . Wel l. he re 'smore ! The new model maintainsall the features of the OX-70T

Palomar EngiJ rt1 S announces anew field strength meter, Model

PfS-1, for serious arnerma vl.1lrk. IIfeatures adctcctor linearover rr;.-Iya 30dB range, an accurate step er­tcnueror with 30dB mnge, a 25 dBRF amplifier. high Q rurcd circuits

to suppress out-of-band local sig­nals and a panel meter read able to.1dB.

Theneterco vers 1.8 to 150 M II/.and is powered by 9- or 12-voll hat­teries. Antenna CCJl1In.1ion isun so­239jockon tre rearof!he aluminumcabinet. All this, and the PFS-I is

peced a only S195 ~ For further in­formalim contact Palomar r:.ngi­r'ICCJS. PO. Box461111.Esc"OO.1idoCA 92().U): Ptl)llC (619)747-33-13:FA X (6 19) 747-3346: E-mail75353.2175@rompu.·;c:ne.com

Field Strength Meter

fee t). and is priced a t $ 110 plusshipping and ha ndling. For moreinformation, co ntact Dyn amicElectronics . Inc.. P.O . Box 896,Hartse lle AL 35640: (205) 773 ­2758; FAX (205) 773-7295 orch ec k i t OU I a t IlTT P :/ /www.bs v.ris.nct/cdc i.

and lighting before you tran s­m il . then sho ws yo u your videoso you can fi ne -tu ne.

It ' s compact, rugged . an dsu rp ris ing ly inex pen sive , a t$329 (Includi ng shi ppi ng in thecontiguous USA). If you ' re aIlcensed ham. COniaC I PC E1ee­tronics hy pho ne. snai lmail o rE-m ai l fo r det ails at 2522Paxson Ln.• Arcadia C A 9 1007.Phone (8 18) .w7·4565 ; E-mai ltomsmb @aol .com.

The ne w Contact East catalogsuppleme nt is 48 gorgeous full­color pages of test equipment .tool s and supplies for engineers,hobbyists. managers and tcchni­d ans. All the brands yo u trust.all products fully guarant eed,a nd Co ntact East promi se ssame-day shipping on ordersplaced by 4P~1. To gel your freecopy. ca ll (508) 682-1000: FAX(50S) 688-7819 : write Co ntactEast. Inc .. 335 Willo w Stree t.North Andover ~A OI 845 .

wide handw idth on each band andcan handle maximum po wer, andit is $ 129 plu s $6 shipping andhandling (US and Canada) . Al soavailable is the DP-2, whi ch cov­ers 40, 30, 20. 17, 15, 12.11, 10.6, ami 2 me ters . T he OP-2 is only65 fee l long (maxi mum width 2

New Multiband Dipole Antenna

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If you 've p lay ed with theFCC part 15 "rabbi ts" you 'llfind thai this new ATY tra ns­m iller fro m PC Electronics willallow much greater scope andrel iab ili ty. T he new T X33- 1h3J~'m band (902-928 :\lHz) 1wall transmitter is sturdy. ac­c ep t s v ide o from mostcamcorders. ca meras or VC Rs.and has an I I- mile snow-freeline of sight DX. A video moni­lor jack lets you set up focu s

More Fun Than Rabbits

Dynamic Electronics Inc. an­nounces the ir new multiband an­tenna for HF and VHF. The DP- I

covers 80, 75 , 40, 30. 20 . 17. 15.11, I I, 10. 6. and 1 meters . It' s125 feet long and has a max i­mum width of 2 feet. This X-di ­pole clement truplcss antenna has

84 73 Amateur Radio Today . January 1997

Need Answers ?

It's Free!

several companies for fo rm ingpart s.

In the earl)' days of testing theeq ui pment one technician d idn' twant to bother se ll ing up a spe­cia l j ig , so he just held the pan tobe fo rmed in his hand and le tloose the magnetic btast . Hishand got a se ve re bum tha tshould have taken ut least s ixmont hs to hea l. A few days laterit was healed, T hey tried 10 inter­est people in the medica l field,but got nowhere.

One o f their people got hisankle shattered while skiing inXcvada. Gangrene set in so heW;IS flown to a hospital in SanFranc isco , ....'he re they wanted toamputate. Friends brought himto the magne tic unit and twodays late r the gangrene was fad,ing away. When the doctorswent to o perate the ankle hadhea led . The medica l communityrefu sed to 1001.. at what they ' dfou nd.

If you've read any o f thehooks I' \"C recommended o n themedica l indust ry this will notsurprise you.

n foelcc trfucat ion

fo r S1.00. These arc T 1·3/4 yellowLEDs, water clear, 2,1 volt at 20mA. Each prod uces 550 mcd lightlevel. much brighter than the diodesspecitied in the anic le. Use fiveLEO,29s in series .... ith a 120-ohmII-I\\" resistor for a far brighter lightsource." ... J . Frank Brumbaugh

ConUm lt'd on page 8 7

Reader Baluch in Ohio wrote10 say that he had taken a sbon ­cut with the b ioclcctn fie r, lieused IwO dimes. a 27V batte ry[ three 9 Vs) and a microammcrerand d id n't bother s....uchmg po ­la rity. He j ust ta r red the currenton and o ff. l ie said that hestarted losing weight imrncdi­atcly and is now down tu his nor­mal weight , his memory hasimproved (he's 72), and he'slooking fo r some hai r 10 sianregro wing next.

We l l. Bo b Reck gre w a ne whead o f hai r, so who knows ?A nd t he n rheres th at c hapwho w as struck by lig htn inga nd gre w ne ...... hair a nd a newset o f tee th. FlJ

"After my article descended imothe depths of the magazine's com,purer S}'stCIIl, I discovered a sourceof brigh ter yellow LEOs: All Elec­tronics. Po . Box 567. Van Nuys CA9 1-108-0567: Cal. #LED-29: four

Numbllr 85 on your FeedblfCk card

:\ Iagnt'lic lIt'a lin~?

NEUER S RY DIEConrilllwdJrom page 8 3

I' ve read a good dea l aboutthe power o f magnets to help thebody heal. I've even reviewed acouple o f books on the subject,and I have a good fr iend I mel atthe Global Sciences Conferencein Tampa earlie r this year whois an expert on the subjec t. SoI wasn ' t complete ly surprisedwhen I got a le iter fro m a reade rwho was ac tive in the ea rlylinear accelerator days.

Il l' ex pla ined that the re ­searchers for General Atomic,working on the linear acceleratorfor Lawrence L ivermore inSan Francisco , were surpr isedwhen thei r magnet ic doughn ut­shaped co ils coll apsed thecopper tube s the coi ls werewound around when the ca­pacitors were d ischa rged intothe coils. T hey didn't knowtha t nonmagnetic material ssuch as copper, brass and alu­min um co uld be fo rmed bya high e nergy impulse mag­ne t ic wave . Once they d isco v­ered this they so ld units to

the fo rest of rotten law s we ' veallowed Congress 10 usc to stealour money and spend it on stuffthat is ru ining what could be oneheck o f a count ry.

If you just nod and sit there ,nothing is going to change forthe be tter. but we know fromhistory that it is going 10 keepge ll ing worse. and o ur kids arcso poorly educated and strippedof creat ivity and guts by ourschools that they're going to ac­cepr whatever comes a long, thesame way you have.

Sermon o ver. Oh yes, thanksto Wal ter Williams and DonFeder fo r the stat ist ics I stolefro m their columns.

Handbook on CD-ROM

UPDRTES

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antennas. fee dh ncs. etc .Gel both.

The bad issues o f QST a reno w ava il able o n C D, from

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T he A R RI. has announcedVo lume 5 o f the i r Antenn a

Compendium series. II includes-I I articles and a disk I IB.\I for­mal ) with da ta for use with an­

tenna plou iug a nd mod eli ngprograms. $20.

CST on CO!

Frank speaks... a far, far brighter thing I do ...

This co mes from J. fran kRJlJJlDaughcoecemmghis :-O;ovemher'96 uncle, "A Low Current Light":

--...._..........-RadioShack.

---ANSWERSR

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Anyone in terested in radioc un ge t t h is ha ndy li llie(5-1/2 x 4- 1/4 inches) guide bysending name , address, and twofi rst class stamps to : RADIOC LUB G UIDE, P.O. Box 103,La rgo FL 33779 -0103.

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73 Amateur Radio tcaev » January 1997 85

JAN 26

ORLANDO, FL The O rlandoHamCation Show and ComputerSh ow, A R RL North Flo rid aConvention will be held atc entre! Florida Fairgrounds, AI.50, 3 mi. west 011-4. Sponsoredby OARC 01Or lando. Setup Fri.9 AM- 5 PM. Open to the publicFri. 5 PM-9 PM , swap tablesonly. Sat. 9 AM- 5 PM; Su n. 9AM-4 PM. Largest tailgate areain Flo rida . RV ovemne parking$16. Advance tickets $6 , $9 atI he gale . Free parking . Swaplables $25fTa ilgate $15 all 3days. Forums: NASA Asl ronaut,Slide/Photo Exh ibil of LightningStorms, ARRL, AP RS Demo byBob Brun inga , WX Downloads,W X Equip . lo r th e Home ,Sho rtwave Li stening by BobGrove, Pub t. Monitoring Times,Bu ild a V HF SW R Meter,Grou nd ing lo r Li ght ning,Antenn a Workshop , Ra d ioTest ing , OX Speaker AIHernan dez and Ladies 'Prog rams . Fo r Into and adv.tickets, contact OrlandoHamCation , P.O. Box 5478 11 ,Orlan do FL 32 8 54 . E-ma il :kd4jqrOao/.eom. Web Pa g ewww.cycat. conlus8rs!oare.

ODENTON, MO A Post HolidaySwapfest and Flea Markel willbe held by Ihe Mary landMobileers ARC 8 AM-2 PM atThe Odenton Vol. Fi re Dept .Hall , 1425 Annapolis Rd. (Roule175) . Free VE exams, pre-reg .with Je rry Gavin NU3D, (410)76 1- 1423. Talk-in on 146.205/.805. Don ation $3 . Tables inadvance $7 (tab le an d on eoperator) . Contact Bill ZieglerKA6TYY, 1307 Ashburton Dr.,Millersville MD 2 1108. Te l. (410)987- 2384 eves.

FEB 14

JAN 28

DOVER, OH The Tu sco ARCHamtest will be held at the OhioNat'!. Guard Armory, 2800 N.wooster Ave ., slarting at 8 AM.Serup starts at 6 AM.Admission $2donation at the door. Tables are $8each. For info and tables , contactTuseo ARC, c/o Howard BlindKD8KF, 6288 Echo Lake Rd. NE,New Philadelphia OH 44663.Please bring your own extensioncords. 120 volts Is aveuebre . Sendreservation orders by Jan. 12th toT usco ARC, clo Howard BlindKDBKF. Talk-in on 146.730(-)

RICHMOND, VA The RichmondAmaleurTelecommunications. Soc.will hold "Prcsttest 97- at theShowplace, 3000 MechanicsvilleTpk,e. I-95, exit 75 to I~ East, thenexit 192 (At. 360 Eas1), go 1/2 mi.on left. Hours 8:30 AM-3:3O PM.Indoor dealers' flea market, forums.Wheelcha ir accessible. Talk-in146.88128.Admission $5. Dealers'tables $35, flea market tables $15(must RSVP by Jan. 4Ih). ContactCraig Spain, (804) 526-9838 eves.,or writa Richmond Frostfest '97,P.O. Box 932. Chester VA 23831.For general info, call (804) 739­2269, ax!. FEST. Intemet at http://trostfest.rars.ner.

YONKERS, NY A Giani ElectronicFlea Markel will be held by theMetro 70Cm Network 9 AM-3 PMat Lincoln H.S., KneeiandAve., Tel.(914) 969-1053. Doors open 7 AMfor vendors, 9 AM for buyers. Newand used equtpm ent for CB,amateur radio, commercial two­way, compute rs. stereo bu ffs ,electronics parts and kits , plusmuch more, wil l be on sa le .Donation $6, kids under 12 free .Tl\ble semp at 7 AM. VE Exams 9AM--11 AM. Contact Dno SuplisldWB2SLO, (9 14) 969-1053. Talk-inon 449.425 PL 156.7; 223.760 PL67.0, 146.910 Hz, and 443.350MHz PL 156.7. Ma~ reservalions toMetro 70 CM Network, 53 HaywardSt. , Yonkers NY 10704.

JAN 19

BROADWAY, OH A Winter HamAado Fair wiI be lijXlnSOfed by ItleUnion County ARC 8 AM-3 PM, onStale Hwy. 347three tenths ofa "'"weslofStale FbJIe31.Free parking.Toels $2 at the door; no advancesales.Age 16 and under free. 8-foottables $10 lor futl lengltl, $5 lor hat!.Reservation s are encouraged .Please forward payment with anSASE 10 Union County ARC, 0"0

Gene Moore N8YRF, 2446 1Claibourne Rd., MarySVille OH43040. Tel. (93n 246-5943.

exh ibito rs and f lea markel allIndoors. Free parking . Admissionby pre-reg. is $2 each or 3 for$5; at Ihe door, $3 each or 2 for$5. Pre·reg. requests receivedaller Jan. 8th w ill be held a tthe door. Swap ta b les $9each fo r the f irs t two tables .Commercial exhibilors welcome;write lor oetene to NorthwestMissouri Winter Ham /es t, c/oGay len Pearson WB0 W, 12 10Midy ett Rd .. St. Joseph MO64506.

ST. JOSEPH, MO The MissouriValley ARC, Green-Hills ARCand Ray- Clay ARC will sponsorthe 7th annual NorthwestMissouri Winter Hamfest, 9 AM­4 PM at the Ramada Inn. Themotet Is located at 1-29 andFrederick Ave. (exit 47 on 1-29),and is offering special rates lorhamlest partic ipants . Major

JAN 18

6 AM. The ev ent Is bei ngsponsored by the Amateur RadioCouncil ofArizona. Free admission,parking $2, lailgaters $5. Talk-Inon 154.43- 146. 52 . ContactMark KC7BXS, (602) 931 -1204;or Ralph weDNO, (602) 582­8208.

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LOVELAND, CO The NorthernColo ra do ARC will ho s ttheir Winter Superfest 9 AM-3PM al Ihe Larimer Co untyFairgrounds, 700 Railroad Ave.VE Exams, commercial exhibits,computer and radio goodies ,more . Reserve tables fromJeanene Gage NOYHY (970)351-7327. For general inlo, call(970) 352-53 04 . Tal k- In on145.1 15(-) 100 Hz.

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PHOEN IX, AZ The ThunderBirdARC will nest tne weetreer­West Va lley Hamfest a lGlendale Community College ,North l ot , 6000 W , Olive(Dunlap & 59th Ave.), slarting at

JAN 11

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Listings are free of charge as space permits. Please send usyour Specjal Event two months in advance of the issue youwant it to appear in. For example. if you want it to appear inthe April issue. we should receive it by January 31. Provide aclesr, concise summary of the essential details about yourSpecial Event.

86 73 Amateur Radio Today · January 1997

WESTERN UNITED STATES TO:

. EASTERN UNITED STATES TO:

For f:ltItl a n' ,"""," '

13--518" posoos 01 318"............... 1J.Ibrog (....."""""

, 3" p-. at 318".............. fubongl_- ,12-518" posoos 01 318"....."nn"'" lUtHng (ft'""''-01")

'2_318' _ 01 318'alu"..num ' ub,,'Ifl (~

"' ''''''01")

2 · 114 " p,_ 01 318' 00a luminurn ,u ~,ng

1 0 " 0 20" poeoe 01 I '~... aIumnJm_.~

t

,

,

signal take-off) and horizontalpolarization for receiving anten­nas (less noise ) on 160 meters.

When using the "T ime. Band.Country" chart: Where 10 metersis shown, also check 12 meters :where 15 meters is show n. alsoch eck 12 mete r s; w he re 20mete rs is s ho wn , a lso check17 me ters ; whe re 40 me te rsis shown, also check 30 meters.T he ionosp here is not cons istentu t a ll t imes a nd loc at ion s :hence the band s shown are alsoinconsistent . FaUPDRTESConfiTIuedjrom PUUf! 85

Vagi update

If a pan s list see ms a bit toosmall, it j ust may be.

Here is the lisl that was omit­ted from the October issue 's '"440Vagi Link Ant ennas" :

JANUARY 1997SUN MON TUE WED THU FAI SAT

1 F 2 F 3 F·P 4 P

5 P-VP 6 VP-P 7 P-F 8 F 9 F 10 F ll F

12 F 13 F,G 14G 15 G·F 16 F 17 F-P 18 P-V

19 VP-P 20 P-F 2IF 22 F 23 F 24 F"G 25 G-F

26F 27 F 28 F 29 F 30 F-G 31 G

DX toward Europe in Ihe lateafternoon and evening on Good(G ) days until midnight. and thentoward the O rient in the earlysunrise hours . Poss ible long-pathDX in the morn ing and also shortskip most days out to a thousandmiles or more, and farther in theevening.

20 meters

40 meters

30 meters

DX to most areas o f the worldduring daylight hours. peak ing afew hours after su nrise and againduring the early afternoon. Al­though the band usually closessoon after sunset, you may findoccasional o pe ning!' 10 Sou thAmeric a and A nta rc tic a u nt ilmidnight . Day light short skipfrom several hundred to 2,000mi le s o r so po ssib le o n mostGood (G) or Pair (F) days.

OX tow ard Europe and Africain late afternoon hours, towardS o ut h a nd Centra l A mericaaround sunse t. and good open­ings to the West and South Pa­cif ic peaking around sunrise onGood (0) da ys. Expect daytimeshort skip to 1,000 miles. and2,000 miles at night.

80-160 meters3/8 ' by 3·1 rJ. " p'<IC<O 01 minalumi num _et . loe+< (10'

Both arc exce llent bands for lIamma .......len!\be>

DX durin g hours of darkne ss, 7J8" by 2 · 1I2' p-. 0I #>ina~num loe+< ( lor

peaking at midnight and just be- SQ..2 39 .

fore dawn. Dayt ime skip on 160 II fftI by' " _K.'""prog___ ..,.... (lor

is nonex istent . NJI on SO it can """"''''11'' PH"" ISO far)

be up to 500 mile s, and over 2 U by 3llJ" """"',, _""'" ..... - ...., (lor2.000 miles at night. O n 160. IJI'Ir"W"IISltaPl

short ski p can reach from I.()()O.. 1 3-112" _ at ~~ toe.WIl l> 0UlGI .,.,..., """ _

2.500 miles at nigh t. Experts pre- .....-..d (~l

fer vert ica l po larizat ion for 1 U damp (101" rnounh"ll

transmitting antennas (low-angle boom 10 "",.1> m73 Amateur Radio Today . Janua ry 1997 87

10-12 metersA few po ssible daytime F2

layer ope nings 10 Sou th and Ce n­tral Am erica 011 the Good (G ldays.

15-17 meters

Fair OX openings on Good(G) days between noon and sun­set. and short-ski p openings dur­ing the daylight hours. The bam!dies at sunset.

weekends also. Geophysical up­sets may be expected betweenthe 5th and 7th as wel l.

GMT: 00 '" " 06 06 tc ta " te te 20 22ALASKA 20 20ARGENTINA 20 4' ., ., 00 00 20 15 15

AUSTRALIA 20 20 ., 4' 20 20 15 15

CANAL ZONE 15 20 20 ., ., 20 20 15 15 15 15

ENGLAND 20 ., BO ., ., 20 20 20 20 20 20HAWAII 20 20 ., ., OJ 20 15 15

INDIA 20 20 ., 20 tsJAPAN 20 20 20 20MEXICO 15 20 20 ., ., 20 20 15 15 15 15

PHILIPPINES 20PUERlO AICO 15 20 ., 20 " rs rsSOUTH AFRICA 15 20 20U.S.S,R. e .,

EST OAST

ALASKA

ARGENTINA 20 4' 4' eo 15 15

AUSTRALIA 15 ., 20 20 20 15

CANAL ZONE 20 00 ., ., ., ., 20 20 15 15 15 20

ENGlAND., ., ., BO 20 15 20 .,

HAWAII 15 20 ., ., ., 15 15

INOlA 15 20 20 " 20 20

JAPN< BO " 20

MEXICO 20 BO .," " " 20 20 te 15 15 20

PHILIPPINES 20

PUEATO RICO 20 BO ., .," " 20 20 15 15 15 20

SOUTH AFRICA 20 ., 15 15 20 20

U,S,S,R ., ., ., 20 20

ALASKA 15 20 .,"

., ., ., 20

ARGENTINA 15 20 40 ., ., ., 40 15 15 15

AUSTRALIA 15 20 20 ., 00 ., 15 15 15

CANAL ZON E 20 20 ., eo " 20 15 15 15

ENGlAND BO ., 20 20

HAWAII 15 15 20 20 20 20 15

INDIA 20

JAPAN 15 20 .,"

., ., ., 20

MEXJCO 20 20 ".,

" 20 15 15 15

PHILIPPINES 15 20 "., 20 20

PUERlORICO 20 20 ., ., ., 20 15 15 15

SOUTH AFRICA 20 ., ., 15 15 20

U.S.S.A.., ., ., ., 20 20

EAST COAST BO 00 ., eo ., 20 20 20

Seasonal lows in so lar nu xvalues, combined with the co n­sistently lo w flux values (60s andlow 70s) al the end of Cycle 22and the beginning of Cycle 23will 110/ bring smi les to the f ,Il' CS

o f DXcrs this month. Conditionsare ex pected 10 be Fair (F) ortrending around Fair for manydays of the month, b ut t herewi ll be [ew Good (G ) daysand mCIIlY Poor (P) or Very Poor( V P) days... unfortunately, o n

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UE21011K- Ea..",' \'on Antmml It md huok by [}J.\'C lngra mK.tnn AllI f the rccocd di"rrensiuns for a full r.ulge of easy 10 bu ik! and erect "skywires." $9.95WGP87034 AUAbout Cuhic-d1 Quad Antennas hy william Orrand Stuart

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jaJ"icnnas. 1..10.00t"·GP87107 ADAbout Vertical Antmna'i by Wllli:un Orr. Coropetensivefo'·cr.tge ofamacur l1.lITlJTlJnicaion\.. $13.95iWGP87{).1:! Beam Antenna HandhlMlk. by WiUiam Orr ard Stu;U1 Cow1\1\.

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HEATH COMPANY is selting photo­ccces of most Heafhkil manuals. CAyauIhonzed sooo:e lorcopyright marulIs.Phone: (6 16) 925-5899. 8-4 ET.........TIRED OF IRONING? ss PCB seoee.No $ se lup, rree sca rv llng available.RRST PROTO. 4201 Univel"3lly Drive.' 102, Ourl1am NC 27707. (9 19) 403­8243. BNB5005

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-Tlnl you" old ham and computer gear into cash now. Sure. you can _ I lor ahamlesl to try and dump it. but you know you" gel a far more realistic: price If youhave it out where 100,000 aetiYe ham potentiall:luyefs can see ~ lhan the lewtw.Jndred local hams who oome by a nea mar1lel table 0JeclI. your anc, garage.cellar and closet shelves and get cash lor your ham and computer gear betore it's100old to sell. You know you're not going to use il again. so why leave it for yourwidOw 10 ltlrow our? That stuff isn't gening any younger!The 73 Flea Markel, Ba rter 'n' Buy. costs you peenuta (almost)-romes 10 35centsa word fo r ind iVidual (noncomme rcial) ads and $1,00 a word for comrreroet ads.Don', plan on telling a long story, Use erorevarcns. cram it in. But be honest.There are plenty of hams who love 10 fix things. so il it doesn't work, say so,Make you r list. count the words, including your call, address and phone number,Include a check or your Credit card number and eqnrauon. II you're placing a com­mercial ad, include an addi tional phone number, separate from your ad.This is a monthly magac:ine. not a daily newspaper, SO lig.Jre a COl4lIe monthsbefore the action s tans: then be prepared. If you get 100 many calls, you priced "klw. II you donl get many calls. 100 high.So gel busy. Blow the WSI oft. check everything out, maIIE! sure it stil WOfts ngtltand maybe you can~ make a ham sure it Sbl 'M)l1<.$ ri{11t and maybe you canhelp make a ham ne¥I'COI'I'let" or retired old tmerhappy with that rig you're nee USingnow. Or you rriglI get busy on your~ef and puII loge!her a list of smaI gear!

parts to send to those interested? -- 0;;;;;;;;;;;;;,.""",,,, ,~;;;Cm,,-.;n..,JSend your ads and payment to: 73 MagazJne, Barter 'n' Buy, 70 Rt 202N.Peterborough NH 03458 and get set fer the phOne calls. The deadline forthe March 1997 classified ad section is January 12th, 1997,

CABLE DESCRAMBLER KIT · Enjoy all WANTED: Sdlematic diagram or manualpremiumaro pay-per-viewchannels. Easy lor Dumont 1062 Oscilloscope. Alsoassembly. Ofl ly $13,95. Call Johnny Boy need schematic for Knight Ocean Hop·Distribution. HlOO·564-6707. BNB6051 per Re ceiver. Ed AA SCI , 24 W.

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88 73 Amateur Radio toaev » Ja nuary 1997

IT'S BACK! The retum olthe HW-a Hand­000k! Second printing,ModlflCalions for1heHeafh CAP rigs. Flrsl class mail $11. OXadd $4 lor air maii shij:ping. Mike BryceWB8VGE, 2225 Mayl\lwer NW.M3rSsiIonOH 44647. BNB404

MAHLON LOOMIS, INVENTOR OF RA­DIO: by Thomas Appleby, (Copyrighl1967). Second printing available fromJ OHAN K. V. SVA NHO LM N3RF,SVANHOLM RESEARCH LABORATO·RIES. P.O , Box 81. Washinglon DC20044. Please send S25.00 donationWith S5.00 for S&H. BNB420

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