Ham Radio Magazine 1990

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Food for thought. 127.3 3A , 167 9 h% l(rn.0 I% 131.8 3R 173.8 hA Our ncw Universal Tone Encoder lends its versatility 103.5 1A 136.5 4% 179 9 6B 82.5 Y% 141 34A 186.2 72 to all tastes. The nicnu includes all CTCSS. its well H5.4 YA 110.921. 146 ? 48 192.R 7A ;IS Rilnt Tones. Touch Tones, anti Test Tones. No HU 5 YB 114.8 ?A IS1 4 5% 203.5 MI countcr or test cqilip~ncntrequired to set frequency - Frequency ;~ccuracv.+ .I Hz maximum - 4OT to + 85°C just dial it in. While traveling. use it on your Amatcur Frcqucncies to 250 Hz availnhlc on peci:ll order tr;rnsccivcr to access tonc opcriited systems. or in Continuous tonc \.our wrvicc v;rn to check out your customers' rc- Group R ------pCi1tcrs; also. us ir piccc of test cquipn~cntto modulate r..TFFT-TONES: TOUCH-TONES: BURST TONES lour Service Monitor or signal generator. It can even 697 I?lW 1fd)O 1850 2150 2400 770 l33h 1650 luM 2200 2450 opcratc off an internal nine volt hattcry. and is av;~ilahlc 852 1477 17(X) 1950 2250 2.W i'or onc clay delivery, hitckeil hy our one year warranty. WI lh33 1750 ?O(M) ?\(XI 2550 IR(W) 2Iou 2350 Frequency accuracy. + I Hz maximum - 40°C to + 85°C till tone\ in Group A ;in11 Group R arc incluiled. Tone length ;~ppro.rtimately3(H) mh. May he lengthened. Ourptit level 1131 to within 1.5Jh over entire range sclcctctl. shorttnetl or cliniinated hy chxnging value of resibtor Scpi~ratclevel adju\t pots ;lntl c>utputconnections for each Model TE-64 $79.95 tonc ( iroup. Ininiunc to RF a Powereil h-30vtlc. unre~ulatcclat X rna. 6 F= COMMUNICATIONS SPECIALISTS [.ow inipctlancc. low tlistortion. aii,just;rhlc sincwave 426 Wc\t Taft Avcnuc. Orange, C"ilifornra 92hh7 ourput. 5v pak-to-peak (X(W)) X54-0547/ Cal~forn~a:(714) 998-302 1 In\tar~t\t;trt-up. Oft' po\itinn ti)r no tonc output. Reverse polarity protcctic>n huill-in.

HAM RADIO N4TM1, page 44 W7CSD, page 59

- -- GROUND-MOUNTED VERTICAL ANTENNAS 11 JUNE 1990 W.J. Byron. W7DHD, andF.S. Chess. K3BN Volume 23, Number 6 Microwaves: MICROWAVE BASICS 22 BobAtkms, KA 7 GT Publisher & Editor-in-Chief: T.H. TENNEY, JR.. WlNLB The Weekender: PHASOMETER Joel Eschrnann, KSMLD, and Tom Rehrn. K9PIQ EDITORIAL STAFF Editor: INEXPENSIVE SSB FOR 10 METERS TERRY NORTHUP KAISTC Phil Salas. A D5X Consulting Technical Editors: Marty Durham, NBlH Ham Radio Techniques: WARC 1992 Dav~dMcLanahan, WAlFHB B11lOrr, W6SAI Alfred W~lson,W6NIF Robert D. Wilson. WA1TKH VARACTOR DIODES FROM RECTIFIERS Associate Editors: Hugh Wells, W6WTU Peter Bert~n~.KlZJH Tom McMullen. WlSL Joseph J. Schroeder, W9JUV The Weekender: PRECISION CRYSTAL FREQUENCY CHECKER 44 Michael A Covington, N4 TMI Production Editor: Susan Shorrock Copy Editor: Peggy Tenney, KAIQDG Practically Speaking: SAFETY STANDDOWN Editorial Assistant: Beth McCormack FOR THOSE WHO SERVICE HAM GEAR Editorial Review Board: Joseph J. Carr. K41PV Forrest Gehrke. K2BT M~chaelGruchalla. P.E. THE SERIES SECTION TRANSFORMER Hunter Harris. WlSl Charles J Michaels. W7XC Bob Lews, W2EBS Mason Logan. K4MT Vern Riportella, WA2LQQ The Weekender: ANTENNA TUNER WITH A NEW TWIST . 59 Ed Wetherhold. W3NQN Bob Baird, W7CSD

PUBLISHING STAFF Elmer's Notebook: ELEMENTARY ELECTRONICS-WRAPPING Assistant Publisher: UP AC THEORY J. CRAIG CLARK, JR., NX1G Tom McMullen. WlSL Advertising Manager: Marty Durham, NBlH DIVERSITY RECEPTION ON HF DIGITAL COMMUNICATION 67 Advertising Production Manager: Stephen Hall, WM6P Dorothy Sargent, KAlZK Circulation Manager: Susan Shorrock Circulation: Marlon Tuttle Traffic Manager: Phil Alix, NlFPX Book Store: Pr~sclllaGauvin PUBLISHER'S LOG 4 DX FORECASTER 73 Cover photo: Michael A. Covington, N4TMI. BACKSCATTER 9 FLEA MARKET 76 COMMENTS 10 NEW PRODUCTS 8 1 HAM NOTEBOOK 57 ADVERTISERS INDEX 82 READERS SERVICE 82

HAM RADlOMagazine(lSSN0148-5989) ispubl~shedmonthly by CommunicationsTechnology,Inc. Main Street. Greenville. New Hampsh~re030484498 Telephone: 603-878-1441 FAX: 603-878-1951. Subaerlptlon Rates: Unlted States: one year. $22.95; two years. $3895. three years. $4995. Canada and Mexlco one year, $31 00 hM,years.$5500 threeyears.Sl4 00 Anolhercounines onevear $35 00vlasurlace mall only All subscrlptlonorders payable~nU S tunds vla lnternattonal postalmoneyorderorcheck drain on U S bank Internetlonal Subscrlptlon Agents. page 77 M~crot~lmcop~esareava~lablefrom Buckmaster PubllshlngMlneral.Vlrglnla23117 CassenetapesofselectedanlCleSfrOm HAM RADIO areavallabletothe bltndand physically handcapped trom Recorded Per~odicals.919Walnut Street. Phlladelphla.Pann- sylvanla 19107 Copyr~ght1990 by Communicat~onsTechnology, Inc T~tleregistered at U S Patent Ofllce Secondclass poslagepa~datGreenv~lle. New Hampshlre03048-0498andat addlt~onalma~l~ngoffices Sendchangeofaddress ro HAM RADIO. Gmnvilie, New Hampshm 03048-0498 A New Direction

I have just returned from what turned out to be my most difficult trip ever to the Dayton HamVentionTM.During the course of the weekend we announced that Ham Radio Magazine had been sold to the publishers of CQ Magazine. It was no fun to meet with many hundreds of you and pass on the news that we would no longer be sending our magazine along each month. But it was a very rewarding experience to listen as you told us just how much Ham Radio has meant to you. It's been an extremely productive twenty-two years and I like to think that Ham Radio has met most of the goals that the late Jim Fisk, WlHR, and I set for ourselves as we embarked or1 our new venture back in 1968. As Jim pointed out in his first editorial, there is a very real danger in just publishing state-of-the-artmaterial rf you first don't give your readers a clear grasp of the current technology upon which the new ideas are based. We have worked very hard over the years to ensure that a Ham Radio reader would be offered this carefully planned balance of information. This will be your last issue of Ham Radio, the last of 268 consecutive regular issues of the finest technical journal ever published for the Amateur. Beginning next month you'll receive CQ Magazine, with the addition of a good measure of the very material for which Ham Radio was so well known-the most competent technical articles and projects the Amateur will find anywhere. Why the change? I began to think pretty seriously about th~sidea a short while ago when Dick Ross, KZMGA, publisher of CQ Magazine, asked if we would be interested in being acquired by his organization. By combin- ing the strengths of each publication, Ham Radio and CQ, the Amateur community stands to gain. Although we both serve the same audience, our two publications have really been complementary rather than competi- tive as far as the reader was concerned. One was heavily involved with the technical side of Amateur Radio, while the other was directed mostly to the operator. Both organizations have their strengths. CQ has more of the support services, such as typesetting and in- house subscription fulfillment, that help a publisher lower costs. Ham Radio has a very strong marketing and direct mail operation that can be used to add to the strength of the whole operation. The HAM RADIO Book- store is unequaled in our industry. It can play an even greater part if it serves the readers of not one but the two strongest independent Amateur magazines, as well as three other CQ Communications monthlies. I would like to thank the many people who have contributed to the succ:ess of Ham Radio over the last two decades. I hesitate to start naming names because there are so many, ;and I don't want to leave anyone out. Certainly, we all owe a tremendous debt to Jim Fisk. He set standards for the entire Amateur Radio publishing industry, standards all of us must continue to work very hard to meet. The Amateur Radio industry has been very good to us. Without advertising support right from the start, there never could have been a Ham Radio magazine. Just as important ha:; been the industry's encouragement to continue our task of keeping Amateurs at the forefront of modern telecommunications. Last, but not least, have been all of you-our readers. You have done your job superbly. Your letters and phone calls have kept us on our toes and have ensured that we never strayed far from the original ideals that we set for ourselves. What's ahead for the Ham Radio readel? A very exciting future. Although I will not be at the helm, I think that I am not out of place to say that you can expect to see the best of what is good in the magazine you already know molded into an even better product. The expanded CQ will incorporate the best efforts of two of the most experienced publishing staffs anywhere in the Amateur world. Terry, KAISTC, and Craig, NXlG, will still be here doing their usual excellent job along with a number of other members of the Ham Radio team who have contributed so much to our efforts. But now they will have the resources of the CQ organization to further their efforts even more. The results should be outstanding.

Skip Tenney, W1NLB

PS. CQ Publisher Dick Ross, K2MGA, said he would love to hear any of your suggestions or comments about all that is happening and how he might best meet your needs in the future.

4 Ham Radio/June 7990 pullt-;? Q'' m,\ow.h . 31Ul t - -(?nI\ : Illclv- Per>dent transm~tand I recelve f requen- cie s, mode, f~lterdata. auto-tuner data 1 CTCSS frequent!1.

? new TS-y>vsu I!s the firs t r/ ,48d.? ';n"qI'-p3+jb7c.q. Built-in ~nter- ateur Radio trans ceiver to1 utilize fac e for comput~r cor itrol Program- ital Signal Processing (DS PI, a .. . - .. a*... 3 ma Dle tone encoder ^ Built-ln heavy 4 h voltage final ampmer, a1 .I R I rauc tube digital displ;3y and dut y AC power supply and spez digi r with a peak-holel functior PACIjustable VFO tunlnq torque ..-':n". ultiple scanning functions C-43s hand microphone SUVFIIICU I ne I S-YDU~Dcan recelve two rre- Qn?ion:*',?r.c:v:.ioa ~fi !ncles s~multaneously * DSP 10 Dlqital S~qnalPI rocessor * 3tnr' 9 '-+' ' r*!+,-.I Synchrlonized SO-2 TCXC) * VS-2 VC)ice syntht * .. . - - wittI SSB IF slope tun~ng,the dl(jital AF * YK-88C-1 500 HZCW f~lterfor 8.83 MHz IF* ftlte r prov~dessharp ct ;tics for "YG-455C-1 500 Hz CW filter for 455 kHz IF* opti mum f~lterrespon: YK-RRCN-1 270 H7 CW filter for 8 83 MHz IF OYG-455CN-1 250 455 *. \' ~az f , Hz CW f~lterfor kHz IF* YK-88SN-1 1.8 kHz SSB filter for 8.83 MHz IF -.\ I~I 131. -. 50 /power trans~stors rrte YG-455s-12.4 kHz SSR filter for 455 ktlz IF* fina I s~ct~on,result~ng in mlnimtJm dis- *SP-950 External soeaker wlAF fil ter tort1Ion and higher eff~c~ency.FuIt-power -SM-230 Station monltor wlpan di: ;play -down t~meexceeds one hou r. "SW-2100 SWRfpower meter >&*, 'i,?''--1 rm ---,->rnfoqqC b r 'TL-922A L~nearamplifier (not for tuner. * Ru~lt-~nfor the TS-9fiOSD !le t Opl~onalfor the TS-950s -. *jv:t\r. KENWOOD U.S.A.CORl ,.:*:..:+. . COMMUNICATIONS RTEST ~'OUIFM~NI LTI. r\tzllwvuu.s uy~~d-lv~~xIIIYII so11 . - ii)Y ??7A5, ??01 f [)qn P: r!irect rnlxlnq system provldes II r UIgh 0 ,cp IC f:'L or? +)u 1:-1rr lnnc1 Peach. CA or)ROl-57.15 ible performance from 100 kHz 1 KEbJWOOD ELECTRONICS CANPLDA INC 30 P Select v: 2r combir latlons fron dHz The lntermodulat~ond) -,., ,- Llr>, ,i(: JX l!l?f,, 'lf,'I Cinn.7 CQI the front panel tor LW, LDO-- and 500 h7 ., irt le 1s 105 t 2 4 kHz for SSB and 6 kHz for AM.FI Issnuqa. Onlnrln. Cannd,n LdT AC? .mnlrc ''6 qt~rferenIce selections can L)e stored In memory .<,- OI~C~I ;B Slope 7uning, . . ... * hAult'-Drive Pqnd Pass Filter (BPI VET (Var~a~let~anaw~ath -ru ~ning), CW AF tune. IF notch filter, dual. circur'ry. F~fteer~band oass filters ar Radio vois;e blanker w~thlevel control. a- ? in the 'rc ) enhancc RF: ~ttenuator(10,20, or 30 dB), sw~tch- ance. able? AGC circuit, and all-mode sauelch. n". . RGEST HAM OUTLET IN THE WORLD

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-10AR $9'' MFJ-1078 1 Huge 518 inch bold LCD digits let you MFJ-9490 IS the world's '34" MFJ-1701 $2195 MFJ-17028 see thc tlme from anywhere In your MFJ-949D most popular 300 watt PEF, S~~~~TFJ.I~O~Shack choose from the dual clock that $149'' tuner. It covers 1.8-30 MHz, Select any of several antennas from your operating desk with these MFJ has separate UTCllocal time display or the ives you a new peak and average read~ng Coax Sw~tches.They feature mountin holes and automatlc grounding of slngle 24 hour ham clock. !ross-Needle SWRIWattmeter, built-ln unused lerrn~nals.They come with MIJ'S one year uncondlt~onalguarantee. Mounted in a brushed aluminum frame. dummy load. 6 posltlon antenna sw~tch MFJ-1701, $34.95. Six position antenna swltch. SO-239 connectors. 50-75 Easy to set. The world's most popular and 4:l balun -- In a compact 10 x 3 x i7 ohm loads. 2 KW PEP. 1 KW CW. Black alum. cabinet 10x3x11/z Inches. ham clocks for accurate logs. MFJ-1OBB inch cabinet. Meter lamp uses 12 VDC or MFJ-1702B. $21.95. 2 positions plus new Center Ground. 2.5 KW PEP, 1 KW 4Mxlx2,MFJ-1070 2!/4xlx2 in. 110 VAC wlth MFJ-1312. $12.95. CW. lnsert~onloss below .2 dB. 50 dB isolat~onat 450 MHz. 50 ohm. 3x2~2~n. MFJ-81513 Antenna Bridge MFJ-1704. $59.95 4 position cavlty switch with l~ghteninglsurgeprotection '16995 :;"FaI devlce. Center ground. 2.5 KW PEP. 1 KW CW. Low SWR. Isolation better SWRIWattmeter Now you can quickly than 50 dB at 500 MHz. Negligible loss. 50 ohm. 6l/4~41/4~11/4in. .- -. optlm~zeyour antenna for MFJ Cross- peak performance wlth this "Dry" Dummy Loads for HFIVHFIUHF Needle SWRI , portable, totally self- Wattmeter has contamed antenna bridge. a new peak I No other equipment - I readlng func- tion1 It shows you SViR fonvard arid needed -- take ~t to your MFJ-NIB antenna site. Determine if reflected power In 20001500 and 700/50 $2895 . . .. 1 your antenna IS too long or watt ranoes- 9.- Covers---- 8-20--- MHz- too short, measure its MFJ has a full llne Of dummy loads lo sult your needs. Use a dummy load Mechanical zero adlusts for movement. resonate frequency and for tuning to reduce needless (and ~llegal)QRM and save your f~nals 50-239 connectors. Lamp uses 12 VDC antenna resistance to 500 MFJ-2600, $28.95. VHFIHF. Alr cooled, non-~nductive50 ohm res~stor.SO-239 or 110 VAC with MFJ-1312, $12.95. ohms. It's the easiest, most connector. Handles 300 Watts. Run full load for 30 seconds, derat~ngcurve to convenient way to determine 5 m~nutes.SWR less than 1.3:l to 30 MHz. 1.5:l to 150 MHz. 2l/zx2%x7 in. ~~l~~~ code practice antenna performance. Built In resistance MFJ-262, $69 95. HF.l KW. SWR less than 1.5:l to 30 MHz. 3x3~13in. bridge, null meter, tunable oscillator- MFJ-264, $109 95. Versatile UHFNHFIHF 1.5 KW load. Low SWR to 650 drive11.8-30 MHz). Use 9 V battery or MHz. usable to 750 MHz. Run 100 watts for 10 minutes, 1500 watts for 10 110 V C w~thAC adapter, $12.95. seconds. SWR is 1.1:l to 30 MHz, below 1.3:l to 650 MHz. 3x3~7inches.

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Let's assume for the sake of argument that a code-free Amateur license is inevitable, and such a license will be closely related to what the FCC has proposed in PR Docket 90-55. The FCC's version of a Communicator class license would require a written exam based on - but more comprehens~vethan - the present Technician exam. At the same time the Novice license would be abolished as an entry into Amateur Radio. I am firmly convinced that such a code-free license would indeed attract some and perhaps many valuable new members to the Amateur fraternity. I am equally convinced that shutting off the much less technically demanding Novice entry into our service would prove at least as damaging as the code-free license could prove beneficial. My conviction is based on a recent personal experience. My wife, a very bright lady with a Master's degree in Marketing Communications, is taking a basic electronics course. The course is required by her electronics manufacturer employer, who wants his key non-technical employees to understand the language of their field. After helping her cope with series and parallel resistances, inductive reactance and resonant circuits, and seeing how many hours she spends studying to prepare for this class, I have a new and profound appreciation for the difficulty many of us have experienced - even at the Novice level - in becoming licensed Amateurs! The things she's learning in her electronics course are comparable to what is required for the present Tech- nician license. If, as the FCC proposes, technical expertise of this level will be required for any entry into Ama- teur Radio, the door will literally be slammed in the faces of thousands of interested but not technically oriented would-be Amateurs. These are people who, once they became directly involved through on-the-air and at-the- bench Novice level activities, would eventually pick up much of the technical knowledge required for upgrading in a much more pleasant environment that that offered in textbooks and classroc~ms. One of the principal reasons for the FCC's desire to eliminate the Novice as an entry into Amateur Radio is its determination that there's been a good deal of cheating in the Novice licensing process since Novice enhancement has made Novice privileges so much more attractive. Because there was a stipulation when the legislation enabling us to run the Amateur examination program was passed that there should be no charge for administering Novice exams, it doesnY seem likely that VEC organizations could or would be able to assume the financial burden of a formal Novice examination program. However, there surely must be some way to clean up Novice licensing short of abolishing it! For example, why not require that Novice exams be administered only by accredited Volunteer Examiners, working on their own, but with the results forwarded to Gettysburg through the accrediting VEC? The overall added workload for the VEC would be minimal. As a VE with the DeVry VEC myself, I can't imagine any of my fellow VEs jeopardizing their reputations or the reputation of the DeVry VEC by entering into a conspiracy to give some lazy would-be Novice a free ride! And that's just one possible solution - surely others can come up with equally good or better ways to restore integrity to Novice licensing. Whatever we do in our efforts to restore vitality to the Amateur service, let's not shut off one established and vital source of new blood in our attempts to open up a new one! Joe Schroeder, WSJUV

Ham Radio/June 1990 9 Freebanders Versus hookups where we East Coasters would start a net and absorb new- Licensed Amateurs comers across the continent until we Dear HR had a clear channel and could work In March's "Backscatter," I think Bill distances not otherwise available in the Orr, WGSAI, brings up a good point in late evenings? questioning if a no-code VHF license I feel that we lost something by will do that much to increase the ranks jumping on the SSB bandwagon. I was of Amateur Radio. But I can't agree KH6RD dur~ng1947 and 1948, opera- completely that the "freebanders" now ting 10 meters only. This was during operating between 26 and 29 MHz and ask the ARRL and the FCC to get one of the sunspot cycles and the are, in his words, "a lot of happy people their heads out of the sand and do QRM in the islands was tremendous. enjoying the fruits of Amateur Radio something about it! There may have been fewer hams then the easy way." I agree that they may be Bill Harris, KSMIL, but a large percentage were on 10 happy people on the air communicat- Roanoke, Texas meters and all districts would be open ing via radio, but I disagree that they at the same time. A ham in Los are enjoying the fruits of Amateur Angeles and I decided to experiment Radio. At least not all of the fruits. Yes, with the Very Narrow Band FM using they may be communicating with other reactance modulators. We used slope freebanders all over the world and so More on AM phone detection, with sharp crystal filters, and they have 3 MHz to do it in - but what Dear HR found that we could reduce frequency about when the sunspot cycle Reading the letter by KH6CC and deviation to such a low figure that the changes and that portion of the spec- KH6B ('AM alive and well'') in the signal sounded like an unmodulated trum is dead most of the time? March issue brought back some carrier but was perfectly readable We hams simply move down to 15 happy memories l%i like to share. I when tuned to the middle of the filter or 20 meters and continue on. The received my first ticket, W8QXF, in May slope. What was more important was freebander will have only the free- of 1937 and couldn't wait to get my rig that we could copy through the heavi- bander down the street to talk to. What on the air. It was a 6L6 Tritet oscillator est QRM on the band. I think it's a about the other fruits Amateur Radio for CW on 80 and 40 meters. The Tritet shame that more was not done in has to offer - like packet, SSTV, ATV, was a crystal-controlledoscillator that VNBFM for ham use. The equipment RTTY, traffic handling, coordinated could be tuned to either its fundamen- was simple, with excellent audio, and emergency communications, repeater tal or second harmonic frequency and used little more space than a CW sig- operation, and homebrewing your own was not too efficient. I sure raised some nal. The modern narrow bandpass equipment? If just talking on the air blisters making that jewel, soldering filter, with a second filter shifted to put when the skip's in is all you want, then with a plumber's iron borrowed from its slope in the middle of the passband, freebanding may be OK, but if you my dad and heated over the gas flame or more elaborate limiters and phase really want to enjoy the different in Mother's stove. lock loop detection should do a superb aspects that radio communication has My good old Sky Buddy could job with very narrow frequency shift. to offer, then an Amateur Radio license receive the 160-meter phone band and We would all benefit by setting aside is the only way to go. I would often listen up there and wish a portion of the 10-meter band for use My main concern with the free- that I too could work phone. Money of homebrew equipment only on AM, banders is that they're moving up into was scarce and there was no way I VNBFM, and CW. Make this sub band 10 meters, and causing a lot of QRM could buy a modulation transformer. available to new licensees as well as in the CW portion of the band. As long However, an article about Heising nostalgic old timers. Limit power input as they stay below 28 MHz, I have no Modulation in The ARRL Handbook to 100 watts to keep a level playing quarrel with them, but when they start got me thinking. A visit to the friendly field. This could put some of the magic encroaching on our frequencies, I get radio repairman, not a ham himself, back into the hobby for new recruits. quite concerned. If they aren't afraid to got me a 20-H filter choke from a Those who choose not to home brew move into 10 meters illegally, when 10 defunct AM radio. That filter choke, a would still have privileges they now is dead, I guess there is nothing to new crystal for 160, another 6L6, a tele- have. These modes are simple enough keep them from also moving to 15 or phone mike, and miscellaneous small to be homebrewed by almost anyone 20 or any other ham band. parts from old radios got me on phone. and, who knows, might start many a On second thought, Bill Orr just may I spent many happy nights on AM kid on an engineering career as it did be correct. Maybe they will enjoy the phone with my four-tube (including with me. fruits of Amateur Radio for free unless rectifier) rig. I wonder how many Earl Smith, WlBML, we, the Amateur community, get busy remember those transcontinental Groton, Connecticut

10 Ham Radio/June 7990 GROUND-MOUNTED VERTICAL ANTENNAS A little history and some theory

By WJ. Byron, W7DHD, PO. Box 2789, Sedona, Arizona 86336 and ES. Chess, K3BN, 4946 Manor Lane, Ellicott Cit~Maryland 21043

ertical antennas date from the beginnings of radio. GROUND PLANE They were ground mounted with the exception of one \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ highly successful and innovative system, the I I v"Zepp." Its origin seems to have been forgotten, and the Zepp name has come to mean something qu~teunrelated to the original. In the twenties, when Amateurs were herded into the spectrum above 1.5 MHz ("200 meters and below"), theZepp proved both practical and useful as a horizontal antenna. The ARROWS INDICATE INSTANTANEOUS CURRENT FLOW originals, though, were often several thousand feet in length. 1 I They hung straight down from the gondola of a Zeppelin Current filaments and their images over "perfect" ground. (hence the name) - vertically, of course! In those very early days, "spark" transmitters were used. They operated on enormous wavelengths (sometimes kilometers), and a number of them were run at many kilowatts with Thus, while the vertical can be operated right on the surprisingly high efficiencies - 80 percent was rather com- ground, the horizontal can't because the image tends to mon. POZ, at Nauen, Germany operated at 150-kW output, cancel the antenna currenl. It would cancel completely if 85-percent efficiency at the transmitter. Because of the there were such a thing as "perfect earth." The perfect earth extreme shortness of the antenna and the long wavelengths, concept is used extensively for preliminary designs. Ground antennaefficiency wasprobably lessthan 5 percent at most, conditions, when known, aid in final designs. resulting in an antenna current of over 1,000 amperes! There Because the first transmitting antenna was made by Mar- were also 'hrc" transmitters, and two different types of coni (apologies to Tesla, Popov, and probably others who mechanically-generatedradio frequency transmitters, but could have been first) the base-fed short vertical antenna these appeared a decade or more later.1 is called (you guessed it) a "Marconi." It's defined as follows: A Marconiis a current-fedantenna (usually vertical) whose Why vertical? overalllengthis a quarter-wave or less, andis loadedby vari- Vertical antennas were (and are) the only way to launch ous means so that it exhibit.^ series (90 degree) resonance. a low frequency radio field from a location on or near the Those "various means" may include series inductors, ground. The techniques, practices, and experiences of earlier capacitive top hats, or mixtures of both. Most of the early antenna pioneers are still germane today - especially systems used a combination approach. There were two when the subject is verticals. There's not much that's really main reasons for this. The tirst was that erecting a quarter- new after all this time. Our instruments and some techniques wave high antenna for a wavelength of 5,000 meters was have simply been upgraded. impossible then, and would be nearly so today. The second There's a notable, fundamental difference between the involves the "logarithmic decrement" of the antenna, about behavior of verticals and horizontal antennas operated near which there will be more later. Because it was related to ground. The "images" shown in Figure 1 are in phase for the bandpass - those were very broad signals - it was the vertical, but they are opposing in the horizontal case. of great importance to contr.01 (always to decrease) the value

Ham Radio/June 1990 11 of the logarithmic decrement, hence the bandpass. In prac- How do we calculate radiation resistance? tical terms, this meant that inductance had to be added in order to decrease the log decrement, which was subject The radiation resistance of a half-wave doublet con- to government regulations. In 1919, the United States structed of "infinitely thin" wire (a necessity for the original Department of Commerce limited the log decrement to 0.2 derivation) is approxirnately 73.2 ohms.* That value has maximum. been known since the 1880s. Therefore, the radiation resistance of half a very thin doublet would be 36.6 ohms. Ever narrower bandpass This is the generally accepted value for a full length quarter- All spark transmitters functioned by the periodic discharg- wave vertical antenna, unachievable though it is. We deal ing of a capacitor bank through a spark gap. The spark with values less than that because the length necessary gap was either in series with an antenna which was the only for resonance is also a function of the length-to-diameter frequency-determining element in the system (Marconi's ratio of the element. The outcome is resonant lengths that early method), or coupled to a secondary circuit which con- are shorter than the equivalent "free space" lengths. The tained the antenna and various resonating components - net result is an antenna that will always be of lower usually inductors. When a charge was delivered to either resistance than that achieved for the thin wire. Figure 2 of these two basic types, the circuit plus antenna (or the shows the manner in which it changes.2 antenna itself) would "ring," losing some of its energy with It has been difficult to determine the expected radiation each cycle because of radiation and circuit losses. The resistances of variously loaded short verticals, although decrease in amplitude was a constant fraction of the some complicated calculations do exist. Occasionally, a preceding cycle amplitude. That constant was the logarith- curve is published titled "Radiation Resistance of a Vertical mic decrement, and is related to what we now call the "Q" Antenna versus Height," with no indication as to the form of an antenna - except that it is inverse. The larger the Q, of antenna (or what length-to-diameter ratio) it relates to. the smaller the log decrement. The main factor controlling It's usually presented on linear graph paper, though the the log decrement was the amount of inductance in the sys- function is a steep transcendental one which makes it hard tem (as with Q, which is XLIR), thus most of the early verti- to interpret at both ends of the curve. Typically it's been cal- cals were base loaded even though they had very large culated for what we'll call the "base-loaded" case, and is top hats. It was the only practical way to control the log of no use whatsoever for any other type of loading (like top, decrement; the only place you could introduce inductance center, or combination). conveniently was at the base. The large (even by today's standards) top-loading capacitances were the smaller part Simple but workable derivations of the total loading when the wavelength was several kilometers. Some of those early top-loading schemes resulted Figures 3 through 6 illustrate methods for estimating the in 0.05-FF capacitance. The pioneers taught us something rad~ationresistances c)f various antennas with different forms very important - how to construct base-loading inductors of loading. Two of them were first presented in Ham Radio with an intrinsic Q of 5,000 or more. Such numbers are in 1983.3 The derivation starts with one-half of the theoreti- possible when the frequency is below, say, 100 kHz, where cally derived resistance of a free space half-wave dipole Litzendraht ("Litz") wire is practical. Litz wire loses its effec- (36.6 ohms). If you assign 1 A as the value of the basecurrent tiveness above a few hundred kHz. Modern OMEGA and assume that the current distributes itself sinusoidally, antenna systems use Litz wire-loading coils; they are also then the area of the profile will be 1 ampere-radian. combination base and top loaded. The rationale for the derivations is that by allowing for no An about-face Nowadays we try to increase the bandwidth of a vertical, just to avoid having to retune when a rather large frequency shift is made. The signal bandwidth is controlled by the modern design of both the transmitter and receiver. It's a challenge to have a wide antenna bandwidth while main- taining high efficiency. It's especially difficult when the antenna is physically short, as is usually the case with vertical antennas for 80 and 160 meters. This is particularly true when they are placed over good ground systems. We mentioned before that the antenna current for POZ was over 1,000 A (references exist which mention 1,200 A). Today, using more or less typical transmission line impedances of 50 or 75 ohms, a 1,000-A line current would represent 50 to 75 MW. But we know that the power was 'bnly" 150 kW. Why the large current? Obviously, there were ANTENNA L/O RATIO tX 100) very low impedances involved. A characteristic of LF and I VLF Marconi antennas is their low feedpoint impedances, Graph of free-space length of quarter-wave nsonance wnus the given little ground loss. Their actual radiation resistances ratio of the length-to-dlameter of an element. were extremely low, usually a fraction of an ohm. A resistance of 50 milliohms was rather common. That's because they were all physically very short. 'Th~slnformatlon can be found in several sources. We used one of Schelkunoff's antenna books.

12 Ham Radio/June 1990 Meet Your Match eet your match with AEA's new ET- I Econo- , , Tuner. A quality, economical antenna tuner for w under $150, the ET- I is designed to match virtually any receiver, transmitter or transceiver from 1.8 to 30 MHz with up to 300 watts of RF power. The ET- I is compatible with almost ANY antenna including verticals, dipoles, inverted vees, beams and mobile whips that are fed by coax cable, balanced lines or a single wire. For easy connection to balanced lines, a 1 :4 balun is built-in. Tuning Options. A front panel switch control allows you to switch between two 1 coax-fed antennas (direct or through the tuner). You can also switch to a balanced line Or wire antenna. The 'ET-1 Econo-Tuner inside v~ew.' position allows you to switch to a dummy load (such a5 AEA's DL- I S(X) dry dummy load) or a direct connected coax antenna. In the BYPASS position, COAX 1 OUT or COAX 2 OUT can be selected so that the tuner is bypassed, but not the meter circuit. Dual-Movement Meter. The ET- I features a precision dual- movement meter to simultaneously monitor power and SWR. AEA Quality Unique engineering designs have made AEA one of the leading innovators in the amateur radio industry. That same quality and superior technical support make the ET-I your best deal for an antenna tuner. AEA provides technical support from the factory or through your personal computer and modem on CompuServe's HamNet. If you are already a CompuServe member, just type GO HAMNET at any CompuServe prompt. For a free introductory CompuServe membership, call 1-800-848-8 199 and ask for representative #48.

AEA Brings You A Better Exmrience. Advanced Electronic Applications, Inc. 2006-196th St. SW/P.O. Box 2 160 Lynnwood, WA 98036 206-775-7373 Spec~ficat~onssubject to change w~thoutnohce or obligation Copyr~ght1990 Dealer lnqulrles inv~ted CAPACITY HAT TOP LOADING

HEIGHT-8 I

A = 1 AMPERE. RADIAN FOR 36.6 WATTS INPUT

HEIGHT - DEGREES

The curve and its derivation for the top-loaded Marconi vertical. The curve is computed from the expresslon in the rectangular box.

L.k$$CTlVE LOADING 90 -1 2 INPUT 0 19 10 ...... (NOTE REVERSED ORDINATE)

A = 1 AMPERE. RADIAN FOR 36.6 WATTS

36 6 11-~0~8)' RR IBASE-LOADED) = ---- SIN~~[@*01 I HEIGHT- DEGREES I The curve and Its derlvation for the base-loaded Marconi vertical.

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TOP-LOADING CAPACITY HAT HEIGHT = 82 -81

I SUPPRESSED ,\ 0 0 18 10 BASE-LOAD INDUCTANCE

THE CURVE IS FOR EQUAL TOP- AN0 BASE-LOADING. CENTERED EXACTLY; 18~-8~)/2? 45' (SEE TEXT) I HEIGHT (B2 -81 1 DEGREES The curve and its derivation for a combination base and top-loaded Marconi vertical. This curve is tor a combination of equal suppres- sion at the top and bottom. This case and that of the "center-loaded" will produce a family of curves.

900~90-e2

02 i"CENTER;,LOADING " INDUCTANCE t 71

AI +AZ 3 1 AMPERE. RADIAN

THIS CURVE IS FOR EQUAL LENGTHS ABOVE AND BELOW THE COIL AT EXACT CENTER

TOTAL HEIGHT- DEGREES

Curve and its derivation for the center-loaded case. The curve is for a coil in the exact electrical center. Technically this Is a "segmented" antenna.

Ham Radio/June 1990 17 losses other than radiation, any configuration of loading will produce one or more profiles, the sum of which must total 1 ampere-radian for any single antenna. A trigonometric- I algebraic expression evolves for the base current in each 10 A = 45:B=45 : case. This expression is squared and divided into 36.6 watts, 20 THl = 3.14159*A/180 the assumed power input for 1 A in the reference antenna. 30 TH2 = 3.14159*B/180 The quotient is the radiation resistance as a function of the 40 M = SIN(TH~):N = SIN(TH2), exposed element lengths expressed as angles. These deri- 50 RR = 36.6*(~-M)^~/(cos(TH~)1-2 vations provide very good estimates of the radiation 60 LPRINT USING "##I.## ###. ##"; B-A,RR resistances, and can be calculated by anyone who has a 70 A = A-5:B = B+5 handheld scientific calculator. 80 IF (B-A)=<90 THEN GOT0 20 ELSE END There are four derivations. The last one, shown in Figure 6, presents calculations for the "enter-loaded" case. It's of limited use, for two reasons. First, few center-loaded verticals exist in which the top section is the same diameter as that of the bottom - a requirement for the derivation. It's usually a thin "whip." Second, the rules governing the way the derivations were perfomed may not fit the case as well as they do in the first three. It's difficult to determine the amount of "standing wave" that exists on the loading coil, if any at all.* We believe there is some standing wave on the loading coil, and intend to make some measurements to confirm it. However, the existence of this wave may not be important, because the whip actually contributes almost nothing to the transmitted field. Almost all of the signal comes from Short BASlCprogramtocalculate thecurve in Figure5. Thecolumn the section below the coil. Thus you may estimate the radi- lists first, the total length (BA), and the second, Its radiation ation resistance of the antenna by using the expression for resistance (R). Notice that at 90°, both the top and base loadings the top-loaded vertical with the length set equal to that of disappear, and the resultant is the resistance ot a quarter-wave the bottom section plus the coil. Those who build a center- antenna. loaded vertical would be well advised to use a top hat and to place the coil - which would be considerably reduced in value because of the increased top capacitance - directly under the top hat, or to eliminate the coil entirely and resort to top loading alone. It's interesting to note that the coil under the top hat configuration isn't new; it was V TOP HAT / / covered by a United States patent in 1909! 0 3/4 POINT / / The combination top and base-loaded case (Figure 5) A MID-POINT / / was solved for equal loading at the top and bottom; the HEL1C;AL / radiating portion of the antenna is in the exact electrical 0 BASE / center. A simple BASIC program for the computation / appears as Figure 7. Both this concept and that of the / center-loaded antenna will produce a family of curves. You can modify the program to generate the rest of the family.

Probably the most important characteristic of the top- (72MH, DATA) / /./' /" loaded versus base-loaded vertical is that for heights up to about 30 or 40 degrees, the radiation resistance of the top-loaded vertical is nearly four times larger than that of 0 4 8 12 16 20 24 28 32 the base-loaded system. This means that the top-loaded I VERTICAL ANTENNA HEIGHT (FEET) I antenna would be four times as efficient as the base-loaded ------antenna erected over identical ground systems. We don't Measured values from Jerry Sewlck's (W2FMI) antennas erected over recommend using base loading in just any situation, except a nearly lossless ground system for several mpmsentatlve types as a tuning network or part of a mostly top-loaded combi- from his 1973 article, "Short Radial Systems for Short Verticals," nation. These derivations also revealed that all other com- in QST. Used with permlsslon of the author. binations of top and base loading result in radiation resistances between those two curves. input impedance (resistance in these cases) over a very In 1977 Jerry Sevick, W2FMI, published what may be the good ground system of 100 quarter-wave terminated radials. best article in recent literature on short ground radials for The earth conductivity was higher than 30 millimhos per short verticals.4 Jerry tested many combinations of short meter; it doesnY get niuch better than that! We're sure it was (Marconi) verticals over several radial systems. One of his a result of Jerry's well-fertilized back lawn. The curve for the figures, shown here as Figure 8, plots measured values of top-loaded antenna (the top curve) gives a value very close to its radiation resistance because there's virtually no para-

'Work by Robert Lew~s,WZEBS, and the late Edrnund Laport corroborates thls f~nd~ng sitic ground loss and no coil resistance. The other curves

18 Ham Radio/June 1990 VERTICAL ANTENNA HEIGHT (FEET)

A plot of the measured values from Figure 8 (the top curve) curve-fit by the derivation from Figure 3. As there was little ground-loss, and because there was no inductance, the points for the top-loaded system represent radiation resistances. reflect the effects of the various loading coils. Even the con- produce an error of more than 3 or 4 percent in almost any struction of a coil of large wire (like no. 10) will contribute case, and probably less. Simply substitute 35 for 36.6 in several ohms of parasitic res~stance,depending on the fre- all the derivations. quency and inductance. This cannot be ignored. The RF resistance of a 13.8-pH coil constructed of no. 16 silver- A surprise plated copper wire measured 1.6 ohms at a frequency of We've all been told over the years that a shortened 7.2 MHz. antenna results in a narrower band~assthan that of a full- sized vertical. This is quite obviousli true for a base-loaded Proof of performance vertical, but might not be true for the top-loaded system. Figure 9 shows the top-loaded antenna data from Figure In 1989, Frank Chess made some calculations for top- 8 as "curve fit" by the expression for top-loaded verticals loaded systems and calculated the inductance of the verti- from Figure 3. We did this to demonstrate that the coeffi- cal section. He computed both the inductive reactance (Xd crent (36.6) is just that - a coefficient set as a consequence and the radiation resistance (RR) as the element was short- of this particular derivation method. If the original dipole ened. He assumed it to be over zero-loss ground. Conse- radiation resistance calculations had yielded, say, 32 ohms, quently, as the element is shortened, resonance is restored then it would have appeared in the derivations. Jerry's full by increasing the size (capacitance) of the top hat. The length vertical measured 35 ohms. This becomes the new results are very interesting. As a matter of fact, they're coefficient and illustrates how you'd use these expressions. startling. The Q of the vertical decreases as it's shortened Notice how well the experimental data (from 1977-78) fit the down to a physical length of a little over 60 degrees, and curve (essentially from 1982) as published in 1990, even then it increases (see Figure 10). We leave this as conjec- though a refinement to accommodate the decreasing LID ture; we haven't performed any experiments for confirmation. ratio for the points below about 14 feet in height wasn't per- However, if this is true, a totally top-loaded vertical over a formed. Given the absence of measured values for a full good ground system resonant at a 62-degree electrical length vertical (the usual circumstance), a good starting height may have a wider intrinsic bandpass than that of a coefficient for verticals of, say, 1-112 or 2 inches diameter full-sized quarter-wave vertical for a reasonable length-to- would be 35. The arbitrary assignment of 35.0 wouldn't diameter ratio of, for instance, 200 or so.

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I PHYSICAL LENGTH IDEGREES) I

The cumfor the "Q" of a toploaded antenna as calculated by one 7--.. .. of the authors (Chess, K3BN) in 1989. As a full-length vertical is AU OU) PROD^^ &-- shortened, it is assumed to be brought to resonance by a tophat. RAPgER & WILLIAIYIW~ The inductive reactance (X3 of the vertical section is calculated lty Cmmunk w DlsMbuton along with its radiation resistance (R,) in each case. anal mt,81 5) 706-558f With few exceptions, the behavior of most antenna systems is influenced by the ground beneath it. Q

REFERENCES Every month Monitoring Times brings 1 Walter Schulz K300F. Wireless Antenna History. Wllhelm Herbs Verlag. 1988 AvallaMe from everything you need to make the most the HAM RADIO Bookstore lor $1695 plus $3 75 sh~pplngand handl~ng 2 Jonalhon Zenneck Wnelw Te!egraphy lransla!ed by A E Seellg McGrawH~Il.1915 An orlglnal of your general coverage transceiver: derlvatlon was done by Helnrlch Herlz In 1888 the latest information on international 3 WJ Byron W7DHD. Short Vertlcals for Ihe Low Bands,'' Ham Radro May 1983 See Flgures 5 and 6 broadcasting schedliles, frequency 4 Jerry Sevlck. WPFMI. "Shorl Ground Rad~alSyslems lor Short Vertlcals:' OSI: April 1978 listings, international DX reports, propagation charts, and tips on how to hear the rare stations. Monitoring Times also keeps you up to date on FROM BEVERAGES government, military, police and fire networks, as well as tips on monitor- THROUGH OSCAR ing everything from air-to-groundand A bibliography 1909 to 1988 ship-to-shore signals to radioteletype, 52,880 references in 92 chapters! facsimile and space communications. ORDER YOUR SUBSCRIP- The only complete reference guide to Amateur articles in the TION TODAY before another issue world! Revised and up-dated from the softbound edition, this goes by. In the U.S., 1 year, $18; microfiche reference lists 80 years worth of information from foreign and Canada, 1 year, $26. For 297 different sources that include QST (since 1945), the a sample issue, send$2 (foreign,send RSGB's magazine RADCOM (since 1979) and all issues of 5 IRCs). For MCNISA orders ($15 HAM RADIO, CQ, and 73. Includes 5,000 key-word index minimum), call 1-704-837-9200. and author and callsign cross references. Unbelievable value. Worth much more than is being charged! FBTO-microfiche $49.95 0 Please enclose $3 75 sh~pp~ng8 handling P.O. Box 98 A HnM Brasstown, N.C. 28902 RADIO (603) 878-1 441 GREENVILLE. NH 03048 FAX (603) 878-1951 / 122 Ham Radio/June 1990 21 work is based on prearranged sched- Bob Atkins, KAlGT ules, or relies on liaison at lower frequencies (often 144 MHz). Much of the activity on the microwave bands is con- MICROWAVE centrated during contests, local activity nights, or local nets. For example, the BASICS Pack Rats group in the Philadelphia This isn't the column I had originally area hasa 1296-MHz net every Monday planned for this month. Instead I've night at 9:30 p.m. on 1296.1 MHz. written in responseto a number of letters The importance of a good QTH site from Amateurs who want some very never been worked at all! There's a real is paramount on the microwave bands basic information on microwaves. opportunity to be "first" on a band, (especially at the higher frequencies); Because it's easy for me to forget that make the first contact over a given thus there's a lot of portable operation not everyone knows about the micro- path, discover a new mode of propa- from mountaintops. As typical microwave bands, I'II devote column space gation, or make a real technological wave TX power is low (maybe 1 watt), this month to an introduction to micro- contribution to state-of-the-art opera- and antennas are small (a 3 or 4-foot waves. My own personal preference is tion. Even if you don't do any of these parabolic dish on 10 GHz is about the towards weak signal work, so this may things, there's a sense of personal practical limit), portable operation is be reflected in my descriptions of satisfaction and achievement in being quite convenient. Photos A and 6 microwave activity. However, other one of the pioneers on the newly show examples of portable operation modes (like AN, FM repeaters, and developing bands. The low population on 3456 and 5670 MHz by members packet) can be found on the bands. of the bands lends itself to other of the North Texas Microwave Society. What are "microwaveQ" As a working characteristics. For instance, there's no For those not interested in working definition, consider microwaves to be QRM, and in my opinion the overall DX, the microwave bands offer one electromagnetic waves with a fre- operating standards are higher. Listen- other unique feature - bandwidth, quency greater than 1000 MHz or a ing to some of the poor conduct on the and lots of it. For example, the 10-GHz wavelength less than 30 cm. That HF bands is a distressing experience. band is 500 MHz wide and ideally defines the lower frequency limit, but I've never heard any discourtesy, suited for high speed digital data links how high in frequency do microwaves deliberate interference, or other which can rapidly use up bandwidth. go? The answer to this question is undesirable conduct on the microwave Because microwave antennas are somewhat nebulous; an upper limit bands. The low population also highly directional, and DX propagation would be somewhere around 300 GHz encourages a sense of community and is difficult, a number of high speed (300,000 MHz). Within this region cooperation between those Amateurs data links can use the same frequen- there's a subdivision referred to as mil- who are on the microwave bands. It's cies, even when they are close to each limeter waves. It's the area between 30 in everyone's interest to help develop other geographically. Similar factors and 300 GHz, where the wavelength activity - even if it's just so there's apply to other wide bandwidth modes. is less than 1 cm. United States someone to talk to on the air! In a way, Who will be the first Amateur to trans- Amateurs have 11 bands allocated microwave operation is a throwback to mit high speed digital HDTV signals on above 1 GHz, with a combined band- the very early days of ham radio - not the air? One mode uniquely permitted width of 23 GHz (23,000 MHz), so you in technology, but in spirit. on the microwave bands is pulse can see that there's plenty of room! I'II Now let's move on to some of the modulation. Though this mode is pro- define and describe these Amateur technical aspects of microwave oper- hibited on all bands below 1000 MHz, bands later. At this point, you just need ation and see how they differ from it's allowed on all the microwave bands to know that they exist and have an those found on the lower bands. except for 1240 to 1300 MHz and 10 idea of their size. Perhaps the most obvious difference to 10.5 GHz Before dealing with any of the tech- is the shorter DX range. While many As I mentioned earlier, there are 11 nical aspects of microwaves, it may be paths in excess of 1000 km have been Amateur microwave allocations. Ill take helpful to try to answer a question worked, such DX is rare. I'II cover this a look at each one and try to describe wh~chhas been posed to me quite fre- in more detail later, but for now it's their characteristics. Some of these quently. What is the attraction of work- enough to know that range will be a bands have full or partial ARRL- ing on the microwave bands? This is few hundred kilometers. Such DX work recommended band plans. In general, a difficult question and probably has uses antennas with high gain (>20 narrowband weak signal work takes as many answers as there are active dBi), and hence a very narrow beam- place on frequencies related to har- microwave Amateurs. The microwave width. Consequently, you have to know monics of 1152 MHz (for historical rea- bands provide the challenge of explo- where the DX is in order to point.the sons involving frequency multiplying). ration. Many of the bands are sparsely antenna with sufficient accuracy to 1240 to 1300 MHz, or the 23-cm populated; indeed some of them have work it! As a result, a lot of microwave band. This is the most populated

22 Ham Rad~o/June1990 power levels of less than 1 watt. (often containing surplus com- The narrowband calling fre- mercial parts). Currently, there's quency is 1296.1 MHz. The ARRL no readily available commercial band plan has allocations for equipment for this band. The nar- repeaters, satellite uplinks, AN, rowband calling frequency is and digital communications, and 5670.1 MHz. there's activity on all these modes. 10 to 10.5 GHz, or the 3-cm band. Much commercially built equip- Second only to the 23-cm band, ment is available for this band - this microwave band has one of from complete multi-mode trans- the highest levels of activity. This ceivers costing well over $1000, to band is popular because it's easy low power transverter kits in the to get on using wideband equip- N5JJU5 demonstrates portable operation on $140 price range. ment based on Gunn oscillators. 5760 MHz. 2300 to 2310 MHz and 2390 to A Gunn oscillator is a resonant 2450 MHz, or the 13-cm band. cavity containing a Gunn diode. Activity here is much lower than When a DC voltage (about 9 volts) on 23 cm, though it's growing and is applied across the diode, oscil- quite well established in some lation occurs at the resonant fre- areas (like North Texas and quency of thecavity. Power output Philadelphia). Quite a lot of opera- is in the 10 to 100-mW range. tion takes place from fixed sta- Complete commercial wideband tions. Power can still be generated systems (Known as "Gunn- with cheap vacuum tubes(2C39s, plexers") are available for a few $10 surplus) at levels of 20 to 30 hundred dollars. A homebrew watts. Antennas are usually of the system can be built for a few tens Yagi type, but some parabolic of dollars and not much technical dishes are in use. Range is less microwave knowledge is required. than at 23 cm, but considerable Antennas are usually parabolic Nofih Texas Microwave Society Expedition distances can be worked with low dishes 1 to 3 feet in diameter. Any on 3456 MHz. Elevation is contdled by jack- power under good conditions line-of-sightpath can be worked ing up the rear of the van1 WA5TNY is seen (W8YlO's 30-mW, 8-foot dish to using such equipment, but almost adjusting the dish. WA8TXT's 200-+W, 4-foot dish. all obstructed paths require the There were strong signals at 135 presence of enhanced propaga- km; the path could have been tion modes (ducting) which occur worked using 2-foot dishes). The infrequently. The world record of microwave band, and the one narrowband calling frequency is 1000+ km was made using such most like the VHFIUHF bands in 2304.1 MHz. Commercially built a wideband system. In addition to its operational characteristics. equipment is available. The mode wideband systems, there are an Novice operation is permitted S satellite downlink is in this band increasing number of narrow- between 1270 and 1295 MHz. (2401 MHz). band systems coming on the air Conventional vacuum tubes 3300 to 3500 MHz, or the 9-cm which use conventional trans- (2C39) can be used to generate band. Activity is very low, but verter techniques. This is in large power, and power levels of 100 growing slowly. Conventional part due to the availability of com- watts aren't uncommon. Antennas vacuum tubes don't work well at mercial (SSB electronics) trans- are generally of the Yagi type (or these frequencies and power verter components (local oscilla- loop Yagi where 1-wavelength must be generated using solid- tors, transmit and receive mixers). loops replace the usual 112- state devices or exotic vacuum Kits are available for a few wavelength elements like a multi- tubes, like traveling wave tubes or hundred dollars; built and tested element quad). Antennas are klystrons. Parabolic dishes are the units cost about double. Power quite small; a 25-element Yagi is most common antennas. Much of output is in the 100 to 200-mW alittleover 6feet long. Fixed station the equipment is homebrew, range, and this is enough to work operation is common, and a well- though there are now some com- many obstructed (non line-of- equipped station can expect a DX mercial transverter kits available. sight) paths of several hundred range of several hundred kilo- Some NRO (satellite N)equip- kilometers on a regular basis. meters under flat conditions. The ment can be modified for use in Such paths would be difficult, if CalifornidHawaii path has been this band, providing excellent per- not impossible, to work using worked on this band (3977 km) formance at low cost. The narrow- wideband equipment. Most of the using modest power and antennas band calling frequency is 3456.1 operation is stdl done from portable (N6CA's 100-watt, 44-element MHz. stations on hilltops, but a number loop Yagi to KH6HME's 25-watt, 5650 to 5925 MHz, or the 6-cm of stations are developing fixed 4 by 25-element Yagis). Under band. Activity here is very low. station capabilities. Several sta- good conditions, distances of up There are a few stations on the tions have employed ANand dig- to 100 km can be worked with band with homebrew systems ital modes on this band. The

Ham Radio/June 1990 23 ARRL has a 10-GHz contest which takes place every year over two weekends in August and Sep- tember. Last year the leading station (W6HHC) made 78 contacts with 17 different stations and a ' best DX of 266 km. Thirty-one stations made contacts in excess of 100 km. Oscar 9 carried a bea- con on this band (10.470 GHz). The narrowband calling frequency is 10.361 GHz. 24 to 24.25 GHz, or the 1.5-cm band. There isn't much regular operation on this band. The majority of activity involves Gunn oscillator-based systems, though some narrowband transverters have been built. This is the lowest frequency band at which attenuation by the atmosphere (oxygen and especially water vapor) is a significant factor in propagation, Members of the North Texas Microwave Society with their 10-GHz equipment assembled amounting to about 0.2 dBlkm. before the first weekend of an ARRL 10-GHz cumulative contest. 47 to 47.2 GHz. This band has no alternative wavelength name. It's Amateur interference. suggest either 23 cm or 3 cm. If you the lowest frequency Amateur mil- How do you get started on the want to work from a fixed station, and limeter wave allocation. Atmos- microwave band9 Again, this question you want to find the most activity, 23 pheric attenuation is significant at has no simple answer; much depends cm is the band of choice. While the about 0.4 dBlkm. There is Amateur on the individual involved. First, and microwave characteristics of operation activity, but it's confined to one or most important, I'd recommend joining on the band make it somewhat differ- two stations. a local group active on microwaves. I ent from lower frequencies, much of 755 to 81 GHz. This is the highest can't stress this point too strongly. The the equipment and propagation will frequency band on which I am group not only provides help and still seem familiar to VHFIUHF opera- aware of Amateur activity. encouragement, but also gives you a tors. Activity is high enough to make Atmospheric absorption amounts number of stations to work. Photo C random contacts possible, particularly to about 0.4 dB1km. shows members of the North Texas in urban areas and during activity 119.98 to 120.02 GHz. There's no Microwave Society with their collection periods and contests. Most tranwerter known Amateur operation at this of 10-GHz equipment, ready for one systems use a 144-MHz IF, so a VHF level. Atmospheric absorption is leg of the ARRL 10-GHz contest. If a transceiver or tranwerter is required. around 2 dBlkm. local microwave group doesn't exist, try Commercial equipment is widely avail- 142 td 149 GHz. No known to find a VHFIUHF group. You'll pro- able and a lot of homebrew designs Amateur operation - there's bably find some microwave knowledge have been published. Check out the atmospheric absorption of and interest there, even if there's no "UHF and Microwave Equipment" around 2 dBlkm. activity. If you can't find either, try to find chapter of a recent ARRL Handbook 241 to 250 GHz. No known another ham interested in developing for ideas. Of course it's not necessary Amateur operation - atmos- microwave capabilities. You can share to start out with a complete tranwerter pheric absorption is in excess of knowledge, help each other with con- system. Operation using a receive con- 5 dB1km. struction, and be certain of someone verter and tripler from 432 MHz is quite Above 300 GHz. This is the to work once you get your station built! possible using CW and FM. It's not as highest band (if it can be called What can you do if you really can't find convenient as a tranwerter, but is that, as there is no upper limit). I any help? If all else fails, write to me cheaper, easier to build, and quite know of no Amateur RF work in and I'II try to put you in touch with capable of yielding equal results. A low this region, but if you go up high someone in your area. If I don't know power 432 to 1296-MHz tripler can be enough in frequency this "band" of anyone, I. can put your call and built using IN914 diodes (10 cents includes lightwave (laser) commu- address in this column with a plea for each!) and, despite a power output of nications, where there is activity. help. If that fails, you'll just have to less then 1 watt, I have personally used Many of these bands are shared by change QTH! It's also important to read such a tripler to work distances of radiolocation (radar) services and you up on the subject. There are some > 50 km. must tolerate interference from them. good microwave books covering both On theother hand, if you likethe idea In practice, this isn't a problem. There theory and practice; I'II list a few at the of hilltoplportable operation, and want are also some nearby radio astronomy end of this article. to try out a band with very different bands which are protected from Where should you start to worW I characteristics and equipment from the

24 Ham Radio/June 1990 lower bands, then 3 cm is the band of print any detailed technical information Conferences. These publications cover choice. You won't make any random about how to build simple microwave all aspects of operation, theory, and contactson this band, so you must be in equipment this month. I hope to return practice on the bands from 50 MHz to contact with at least one other interested to this topic in the future and try to lightwave. A good way to keep up with Amateur. There are two main modes of present some simple projects. the state-of-the-art technical develop- operation on 10 GHz. First, there are ments by those in the forefront of w~debandsystems with IF bandwidths Recommended reading VHFJUHFand microwave work. Some, of 50 kHz or more, which use free run- The following publicationsare recom- but certainly not all, of the material may ning cavity-stabilized Gunn oscillators mended for those who want to learn be a bit advanced for absolute begin- and usually operate using FM. Second, more about microwaves. Someof these ners. (Available from the HAM RADIO there are narrowband systems with IF books are available from the HAM Bookstore. Check current book flyer bandwidths of 3 kHz and less, which RADIO Bookstore. and advertisements in this issue for use frequency multiplication and m~xing The RSGB VHF/UHF Manual. Lots of prices.) from lower frequency crystal-controlled information on theoretical and practical And, of course, back issues of Ham sources and operate using SSB and aspects of VHFIUHF and microwave Radio. Check out the 5-year cumulative CW. For low cost experimentation, ATV, operation. Recommended to anyone index which appeared in the Decem- or digital operation, the wideband interested in these bands. (Available ber 1989 issue. You might also want to Gunnplexer route is best. You can pur- from the HAM RADIO Bookstore for read some of the "New Frontier" chase a complete Gunn oscillator- $29.95 plus $3.75 shipping and han- columns which appeared in QSTfrom based transceiver from a commercial dling.) 1980 to 1989. source for a few hundred dollars. Alter- The Gunnplexer Cookbook, by Bob natively, you can build a basic Gunn Richardson, published by the Ham Microwave news oscillator/mixer system from a few Radio Publishing Group. A practical As I've mentioned before, microwave pieces of waveguide and a couple of book which describes a large number operation often takes place on local diodesfor a total cost of around $20. By of projects based on the Microwave nets so operators can have a good combiningthisequipment with asimple Associates Gunnplexer system for 10 idea of when and where they'll find power supply and the IF strip from an GHz. A good start for the newcomer to activity. WD4MBK has sent along infor- FM radio (or even an FM radio itself), you 10-GHz wideband operation. (Out of mation on a new 1296-MHz net in the can construct a complete transceiver. print.) Southeast. Dexter Mclntyre, WA4ZIA, Some Amateurs are working on ways to The RSGB Microwave Manual. I still of Stanfield, North Carolina, has started convert surplus Gunn oscillator-based haven't seen thisone, but onthe basisof a net which meets on 1296.090 MHz microwave radar detectors, automatic its authorship it should be a valuable at 9:30 p.m. every Wednesday even- door openers, and intruder alarms to reference. (Available from the HAM ing. The net is held in conjunction with Amateur use at low cost. For serious DX RADIO Bookstore for $35 plus $3.75 the East Coast 70-cm net which meets and weak signal work under all condi- shipping and handling.) on 432.090 MHz at 9:00 p.m., also on tions, narrowband operation is 10 GHz - A ConstructionalProject, Wednesday evenings. On the first night preferred, though it's more expensive by Chuck Houghton, published by the of the 1296-MHz net, there were seven and requires a little more microwave San Diego Microwave Group and check-ins from five states (Georgia, knowledge. Narrowbandoperation will priced at $15. A collection of notes Florida, Tennessee, South Carolina, also make possible many more paths mostly relating to wideband operation and North Carolina). The best DX was than will wideband operation. Wide- on 10 GHz and some information rele- a 500-mile contact between W40DW band systems are quite capable of DX vant to narrowband work. Lots of and WA4ZIA. Stations interested in par- operation under good propagationcon- detailed construction information with a ticipating in the 1296-MHz net can ditions. (In fact, the world and Un~ted little bit of theory. Includes test equip- check into the earlier 432-MHz net, States DX records are held by Amateurs ment, use of converted intruder alarms, where net control (WD4MBK) will take using wideband equipment.) antennas, homebrew and commercial a list which will be passed on to the Equipment is available from a num- Gunn oscillators, and more. Somecom- 1296-MHz net controller (WA4ZIA). At ber of suppliers. Takealookthrough this ponents (IF boards, Gunn diodes, etc.) 9:30, WA4ZlA will call and listen on issue of Ham Radio; I'm sure you'll find are also available from this group. Con- 1296.090, while listening simultane- advertisements for companies who tact Chuck, WBGIGP, at 6345 Badger ously on 432.110 MHz for stations who specialize in equipment for the micro- Lake, San Diego, California 92119. wish to join the 1296-MHz net. Stations wave bands. All should be able to give The RSGB Microwave Newsletter further to the north (Virginia, Maryland, you information on microwave equip- Technical Collection. A collection of New Jersey, and Pennsylvania) should ment, and some may even be able to technical items from the RSGB micro- look for K4CAW (North Carolina). He help you find active microwave stations wave newsletter.Covers practicaldesign will call and listen on 1296.090 at 9:30 in your area. If you have trouble finding information for the bands 1296 MHz to p.m. for check-ins from the north. a specific piece of equipment, I may be 24 GHz. Includes information on oscil- WA4ZIA has also become opera- able to help. However, it's hard to keep lator sources, antennas, filter design and tional on 3456 MHz with 5 watts to a up to date, so check out the ads in the test equipment. (Out of print.) W3HQT loop Yagi. To eliminate feed- Amateur Radio publications first. The ARRL also publishes a series of line losses, the 3456 transverter and I hope this information is helpful to conference proceedingsfrom the Cen- power amplifier are mounted at the newcomers who are interested in the tral States VHF Society, Microwave antenna on top of his tower. In his first microwave bands. There isn't room to Update, and Mid-Atlantic States VHF week on the band, he worked W4OJK

Ham Radio/June 1990 25 RSOS (~eal- me & Storage Osc~lloscopes)From HITACHI Compact Series Scopes The RSO - ~tsthe new solut~on View, Acquire, lest. Transfer and Document Your Waveform Oota Delapd S*rp L~ghtwlght(13hs) . . . 11 .. 2mV Sens IOQMSS(25MS son 4 channels s r~itapeousiyi1CCMhz 4kw x lch 2kw x :ch ~kwx dch 3 Yr Wan*

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r/ 111 26 Ham Radio/June 7990 (95 miles) and K4EJQ (115 miles - The microwave bands are being eyed path open about 10 percent of the increasingly by commercial interests as time). technology makes their use more practical. If we don't occupy the bands we'll Microwaves and no-code have little grounds for objection if we While it's often difficult to be topical start to lose them. If a no-code license in a column written so far in advance can increase microwave activity, then of publication, I'm quite sure that the I welcome it. Even if it doesn't, I don't code versus no-code issue will still be think a limited no-code license will do under debate when you read this. On harm. February 16th, the FCC issued a notice If you feel strongly on the issue of a of proposed rule making (NPRM) in no-code license, I urge you to send their docket number 90-55. If you your comments to the FCC (but do haven't read this document, and are read the text of their proposal first). I concerned with the future of ham favor the idea of the Communicator radio, please do so. Basically, it calls license, but I think dropping the Novice for diopping the Novice and Technician and Technician classes, with their low class licenses and establishing a Com- speed CW requirements, would be a .S<:lr.cmhle Search Incrnrnent9. ARlOOO I, S~!,KIIZ municator no-code license entitling the mistake. Whatever your views, make I ,,., I.,. , r ., ,ht P,P~,~.Perrnitnc~nL memory backurt ~vx(,,.-;..::1,,111,m:~a Opl~onall -7% Day Sauslacllon Ciuamrltl+? holder to all privileges on 222 MHz them known to the FCC, and if the Pull relund 11nor Sausllrd and above. While the debate may be eventual outcome is a new group of $499 ~~%~~~~~~~ncludd fierce (there are those who argue with no-code Amateurs, then let's make Slze 6 718.H x 1 014'L) x 2 112'W a fervor usually reserved for politics sure we welcome them to ham radio Wt IZar and religion), it seems that some kind without prejudice and encourage them of no-code license will be the outcome. to join us on the microwave bands (and You may ask what this has to do with learn CW!). COMMUNICATIONS microwaves. Well, all the no-code Finally, thanks again to all of those 10701 E. 106th St. Indpls.. IN 482. I Toll 1:rr.e ROO 445 7717 I proposals allow - in fact, are actually who have taken the time to write. The Viqir ,anrl Maslt,!card direction and content of this column (COD sl~qlrllyh~qher) targeted towards - newcomers to the FAX (017) R49-H7W bands where more activity is badly depends on your letters, so keep them needed. Much of the fine work done coming. If you send photos, please be in the UK on the microwave bands has sure to include all the information been through the efforts of Amateurs about the photo on the back. Black there who hold no-code licenses. and white prints are preferred, but (Indeed, my first license was a UK no- color is okay. Next month I plan to dis- code, though my contributions to cuss tropospheric scatter propagation microwave activity were negligible!) on the microwave bands. Wllh Our Patenled I Bp B, CIRCUITp FILTERS T? -7

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/ 113 Ham Rad~o/June1990 27 Joel Eschmann, K9ML D, 6964 Meadowdale antenna-tun~ngindicator for the visually impaired. Drive, Hartford, Wisconsin 53027 and Tom Rehm, Help in tuning phased arrays to a conjugate impedance match. KSPIQ, 11653 N. Pinehurst Circle, Mequon, Checking the health of your present antenna. The Wisconsin 53092 PhasoMeter is sensitive enough to see your antenna flapping in the breeze - a feat difficult to achieve with o, it's not another SWR bridge. The PhasoMeter an SWR bridge. is a discriminator that detects the relative phase between voltage and current waves in an RF trans- Calibration mission line. When used with a zero-center meter, it pro- Calibration requires a dummy load or other flat resistive vides an accurate indication of resonance and also shows load. Run 100 to 150 watts through the PhasoMeter into which side of resonance you're tuned to. If you're tuned a dummy load. The load end should be the end opposite below resonance, the meter will deflect to the left; if you're the point where C4 is attached. Adjust C5 for zero deflection. tuned above resonance, it will deflect to the right. At reso- If you don't obtain a null, move C5 to the other side of TI nance, both voltage and current are in phase and the meter and repeat the procedure. That's all there is to it! Calibra- reads zero. The further you are from resonance, the greater tion should hold to within a few kHz across the entire band. the amount of deflection. The amount of deflection is also The design in Figure 1 is optimized for 75-meter opera- proportional to RF power. The device connects in series with tion, with reduced sensitivity on 40 meters. If 40 meters is the transmission line or at the antenna feedpoint. You can your band, wind TI with eight turns.* The basic circuit looks leave the PhasoMeter "in line" permanently if you wish; like the early FM detectors, and it is just that. The principle there are no batteries to wear out. is the same-but now, with the PhasoMeter, you can look Some practical applications include: into the activity going on in the coaxial cable. Use as a tuning aid for remote antenna tuners (like the K9MLD design in Ham Radio, October 19881) by Aids mobile operation indicating directly which direction to slew the inductor. K9MLD has found the PhasoMeter very useful in a mobile This has proven to be invaluable for mobile operation. Providing the essential pickup discriminator for construction of an automatic antenna tuner or an audible 'For cptlrnum perlormance. TI shl>uld be lallored lor Ihe band used Ed

Schematic of PhasoMeter optimized for 75-meter operation, with reduced sensitlvfty on 40 meters.

28 Ham Radio/June 1990 TRANSMITTER ANTENNA

DlSCRlMlNATOR CIRCUITRY

Plctorel representation of the pickup toroid and Its wlndlngs. Note: For clarlty, continuity between the connector bodies isn't shown.

Parts list C1 100-pF sllver mica capacitor, 100 wlt, 5 percent C2.Q O.l-,tF 100-volt, 5-percent capacitor C4 5-pF sllver mica capacitor. 500 volt C5 6 to 50-pF trlmmer (Radio Shack) 01.02 IN914 diode MI 50-4, zerocenter meter R1 12-k, 10-percent, 1/4-watt reslstor (a 2.5-mH choke may be substituted for Increased sensltlvity) R2.R3 loo-&, 10-percent. 1/4-watt resistor R4 10-k. 10-percent, 1/4-watt resistor T1 Amidon 1-50-2 bifllar wound with 15 turns of no. 26 gauge wire' 'Amidon Associates. 12033 Otsego Strect. North Hollywood. California 91607. A typical PhasoMeter unit. PC board available for $3.50 plus $1.50 shipping and handling I fmm FAR Circuits. 18N640 Field Court, Dundee. Illinois. 60118. I installation which uses a manual motor-driven tuner.l Changing frequency and retuning the antenna while mobile Though this type of design has been around a while, the can be a real chore. This unit makes it simple. The zero- earlier models used a "bang bang" style of servo. The new center meter clearly indicates the direction to tune to obtain design will servo the motor and slew into the point where resonance. the motor is at rest. When the motor-driven reactor Figure 2 shows how to assemble the unit. The toroidal approaches resonance, our design will slow the motor core and detection circuitry should be located within an inch down, come into position at the proper point, and stop - or so of each other. The meter can be remote to your dash- instead of stopping abruptly and over-shooting the mark. board or the whole unit can be mounted next to the trans- We have described a discriminator-type device that mitter. We've built a number of these meters and found the attaches to your transmission line and has many potential performance to be equal, regardless of the structure. A typi- uses. You now have a tool that will make tuning your antenna cal unit is shown in Photo A. system even easier and keep it operating at peak perfor- Future plans mance. Q REFERENCES We are working on an addition to the PhasoMeter that 1 Joel Eschmann. WMLD. "The Weekender Remote Tuner For 75 Meter Mob~les:'Ham Radro. will automatically drive a motor-driventuner to resonance. October 1988. page 36

Ham Rad~o/June7990 29

Partial schematic for the reference oscillator In the Cobra 146GTL.

Figure 2 is a schematic of the reference oscillator for the synthesizer in the 146GTL. Diode D30 is a varactor diode \ VOICE LOCK ] (voltage variable capacitor). On receive the voice lock con- I I trol applies a variable voltage through isolation diode 031 to varactor diode 030. This variable voltage changes the capacitance of D30 which then pulls the frequency of synthesizer crystal XI. On transmit the voice lock voltage is removed and a fixed voltage is applied through isolation diode D32 to varactor diode D30. First disable the fixed voltage applied during transmit. This is done most easily by cutting D32 out of the circuit. D32 is located just beneath crystal XI. Next refer to Figure 3 which is a partial drawing of the circuit side of the front panel pc board. Modify this board by cutting the circuit pad near I the voice lock control and adding a wire from the cut pad FRONT PANEL PCB - CIRCUIT SlDE to one terminal of the LSBlAMlUSB switch. This modifica- MAIN PCB - COMPONENT SlDE tion will keep the voice lock variable voltage available 1 / during receive and transmit. As I mentioned before, the total tuning range of the voice lock circuitry is only *1 kHz. Varactor diode D30 doesn't have enough capacitance range to cover any more than this. Fortunately, you can make a very inexpensive varactor Partial drawlng of the trace side of the fmnt panel circuit board. diode. Simwlv re~laceD30 with four IN4000 diodes connected in series as shown in Figure 4. Note that the diode polarities are opposite that of 030. The voice lock circuitry now becomes a current source for these diodes. At verv low currents the diodes don't conduct, and look like an open circuit or very low capacitance. As you increase the current through the d~odes,they begin to conduct. The more the diodes conduct, the more they approach a short circuit. Remember that a short circuit looks like a very high IN4000 capacity. 1 found that three series-connected diodes gave D3. (4 EACH) me +5 kHz tuning range while four series-connected diodes gave me a k7.5 kHz tuning range. Four diodes makes tuning a little more sensitive but gives you some channel overlap. ' The Cobra 146GTL uses crystal XI to determine the USB, LSB, and AM frequencies. To keep the frequencies the Replacing 030 wlth four IN4000 series dlodes.

Ham Radio/June 1990 31 I

Schematic of the modified reference oscillator. same for all three modes, the crystal is pulled by ~nductors Proceed as follows: L16, L17, and L18 - depending on which mode you're in. Make sure the crystal oscillator is operating. You should Unfortunately, the combination of the inductor pulling and see about 50 mV p-p of signal with the oscilloscope con- the voice lock pulling is a little too much for the crystal oscil- nected to pin 13 of IC2. This is a broadband circuit and lator circuit in the USB and AM modes. Consequently, the will operate easily with the new 11.1-MHz crystal. If it's not oscillator may stop while you're tuning with the voice lock working, recheck your modifications. control. To compensate, I modified the circuit to use induc- Set the channel selector to channel 19. Locate TP2. This tor L18 (the LSB inductor) for all three modes. Do this by is the bare end of resistor R93 and is located next to L14 cutting one end of diodes D27 and D28 and replacing (see Figure 1). Attach your digital voltmeter between TP2 diode D29 with a short circuit (a piece of wire). You can and the 12-volt return. C:arefully adjust L14 in a counterclock- still operate all three modes, but there will be a slight fre- wise direction (for less inductance) until you read 3.25 volts quency change when you switch modes. at TP2. As you begin to adjust this inductor, the voltage will Your final hardware modification involves replacing crys- start out low (less than 2 volts) and then increase. When tal XI. An 11.1-MHz crystal will move the operation of the you reach 3.25 volts, connect the oscilloscope to pin 22 146GTL to 28.3 to 28.74 MHz. For each 100 kHz you move of IC2 and peak the observed voltage with L13. You should the crystal frequency, the radio operating frequency will see aproximately 130 mV p-p at this point. move 200 kHz. For example, if you want the radio to oper- If the voltage at TP:! becomes intermittent while you're ate from 28.5 to 28.94 Mhz, use a crystal frequency of 11.2 tuning L14, leave the inductor at the last stable voltage posi- MHz. I ordered my replacement crystal from JAN Crystals tion and peak the voltage at pin 22 of IC2 with L13. Then for $5. When you order the crystal, specify that it must be go back and finish readjusting L14. Follow this by peaking a synthesizer crystal for the Cobra 146GTL in an HC-18 the observed voltage with L13 at pin 22 of IC2. package with a frequency of 11.100 Mhz. When your crys- Now connect the oscilloscope to TP3. TP3 is one end of tal arrives, unsolder crystal XI and replace it with the new resistor R105 and is located next to L6 as shown in Figure 1. one. Figure 5 is the schematic of the final modified synthesizer Adjust L15 for maximum voltage at TP3. Note: Adjust L15, reference oscillator. not L6! You should see about 80 mV p-p at TP3. Connect the oscilloscope to pin 11 of IC5. Press the trans- Tuning up mit button and adjust 139 for maximum voltage. This should Two of the necessary adjustable inductors (L14and 127) be about 50 mV p-p. in the Cobra 146GTL are filled with wax. You can remove Finally, connect the oscilloscope to the center conduc- this wax easily with a small bladed X-ACTOTMknife. I was tor of the output connector on the radio. With the transmit able to remove virtually all the wax in just a few minutes button depressed, adjust L38, L37, and L27 for maximum by picking at it with the knife. output. This completes the transmitter alignment. It's best to perform the following adjustments with a digi- The receiver alignment is also simple. Attach your oscil- tal voltmeter and an oscilloscope. If you use an analog volt- loscope probe to one of the speaker leads. Set the chan- meter, make sure that it is high impedance. You can use nel selector to channel 19 and attach a 10-foot section of a CB-style power/SWR meter in place of the oscilloscope random wire to the radio's antenna terminal. Tune around for the final output power tuning; however, the oscilloscope for a clear area and t.hen peak L3, L4, L5, L6, L7, and L8 is really necessary for setting up the synthesizer circuitry. for maximum noise as seen on the oscilloscope. Make sure Make sure the microphone is plugged into the radio. The you don't press the transmit button since you don't have receiver won't function without the mic. a proper antenna!

32 Ham Radio/June 1990 WGSAI BOOKS Attach your oscilloscope probe to TP1. This is one end by noted HR columnist Bill Orr, WGSAI. of resistor R10 and is located adjacent to L2, as shown in Figure 1. Now adjust L1 and L2 for maximum noise. This ALL ABWT VERncAL ANTENNAS hry.dalgn, anstrudonand aperationarefully aweredlorverlical antennas. Grounds completes the radio alignment. and their i~rponm~getextraerrphasb. ConQructbndatafor25+ antennadeslgns. 192 pages 01986 1st edllon Antennas RP-VA Solbound $10.85 Anv 10-meter antenna will work. But for mobile use I wanted a discreet antenna that I could remove when I Tm RAMO AMATEUR ANTENNA HANDBOOK Covers dl klnda d antennas from HF to VHF. horizontal to verllcal. Corrpiled fmrn yean parked the car. I purchased a center-loaded CB magnetic of WGSAlb extensive mltlngs. Great referetenoe vdume to have on hand. Chodc full d mount antenna from K-Mart for about $15. 1 removed 1-314 pmven antenna designs that work1 190 pager 01978 111 edllion inches from the top part of this antenna to resonate it at RP-AH 28.5 MHz. The entire antenna is only about 2 feet high! INTERFERENCEHANDBOOK by WA6FQO Operation Wkh homes rapidly Illling with vulnerable eleclmnlc equipment, knowing how to solve lmerferenca problem# b a mst. WA6FOG ha8 years ol experbnce and tefls you What Can VOU do with a 2-fo0t antenna and 12 watts PEP everything YOU nad to know to solve even the thorniest Interirenca pmbbm. o 1981 on 10 meters? It depends on band conditions. I work all 1st editbn over the United States and down into South America quite RP-IH reaularlv. If I can hear a station I can work it. unless I'm competing with someone running higher power and a bet- THE RAMO HANDBOOK prd dl(lon Great technical resource to haw evallable In vour Ham mxhhca. Full d all kinds d I ter antenna system. My best results seem to occur when pmleds. antennas and the best wrrpllat~noi HF and VHF arrpilllen In the Amateur I call CQ and state that I am "QRP mob~le."My contacts Radb field. Indudaa new easy-lo-uw chans, graphs curd tablm. Best value h Armteur Radio today. 1200 pages 01968 23 edltbn are always amazed when I tell them what I'm running. 22424 (Reg $29.85 SAM $3) Hardbound $26.95 Summary I Plea8e enclose $3 75 shipping end handling I It's hard to beat 10 meters during the sunspot highs. Over the next few years you can have quite a bit of fun with this HAM rig, for almost half what you'd spend for a 2-meter handie- talkie! The modifications I've described can be done eas- RnDlO Order today1 (603)878-1441 a 'FAX' us (603 878-1951 ily in one evening. Give it a try. If you're like me, you'll wish Greenvllle, N.H. 03048 you had a longer drive to work!-• /' . Enjoy This

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Never clmb agaln wllh thls tower and elevator system. MARTIN TOWERS are made of aluminum ar~dspec~fically engineered for use with THE HAZER.All bolted construction, no welds. Easy to install hlnge base, walk up erection. next pli~mbwith levellng bolts In base. Mount antennas and rotor on HAZER In vertical upr~ghtpos~tlon, then winch lo top of lower for normal operating pos~tion.Guy wires fasten to

SWD 1 I4 7 gDICd HAZER or above HAZER at top of tower. Safety ATV nnmn 4 I 4 1 422439MHz lock system operates wh~leralslng or lowering. FIB ,.!lo hmd.ms Never can fall. Photo shows HAZER and antenna at top YCMANICAL SPECIFICATIONS L."Qlh SPECIAL TOWER PACKAGE prices include 8oom ? BOB1 T6Alummum El.m.nl8 91% Alum8num rod everything but rotor and antenna. 50' M-18 Wmd sulvral 90. MPH alum, tower k~tform, hinged base, concrete U.,, "0 lo l d -,.I EkmN InUIMS BUP C+lm footing sectlon. HAZER k~t,Phillystran guy I wlres, :urnbuckies, earth screw anchors, 10' mast. thrust bearlng, tool kit. rated at 15 sq. ft. antenna load @ 70 MPH. $1925.96 FOB Read All About Your Boonville. FO-12-144. FO-16.220. FO-25-432. FO-33432. Fa11-440 Favorite Modes Of 50 M-13 alum lower same pug as above $1857.95 POWER DIVIDERS ...... STACKING FRAMES I 40 M-13 alum tower, same pkg as above 14a3.80 I 30' M-13 alum lower same pkg as above Digital Communications! 1291.25 We ruwy thou hard to flnd parts lw the home bolder nALER 2 for Ronn 25 - nvy duty alum 12 sq 11 wind la 311.95 Y1.Y D.bn ln.ullos Si2I100. Stalnle~rkwprr SlOllMl HAZER 3 lor Rohn 25 - Sld alum 0 rq 11 wlnd Id 223.85 I I I AM$5 UPS Sli for I.ch mlema I HAZER 4 tor Rohn 25 Hvy gal" Ill 16 sq fl WlOd Id 2D1.05

8i 6-882-2734 \fl 1 $1600 peryear I FAX: 816-882-7200 I U.8. 522 DO Elsewhere PayaMe ~n US Funds Only / Check or M 0 Preferre0 Ham Radio/June 1990 33 A unlque new mob~ledata printer. It incorporates a packet controller with a 40 column thermal printer that operates on 13.6 VDC and interfaces with any mobile radio. In a recent usertest it proved to have about twice as much audio level range tolerance as other TNCs. It is also an ideal unit for emergency work and a commercial version is perfect for dispatching service, emergency and police vehicles.

The FSTV-430A, AEA's newest The exciting FSTV-430 fast scan television transceiver makes getting on ATVeasy and inexpensive.. .liveortaped. Almost anyvideo camera can be used. Simply plug it into the FSTV-430, connect to your 70 cm antenna and you're on the air. Use a standard TVfor receiving signals and, of course, an amplifier will extend your range. It's reliable, portable and light weight and can be used in-station or mobile from any 12 VDC source. The only license required is a technician or higher. I

The PK232/MBX by AEA . . .the only controller olfer~ngMorse Code, Baudot, ASCII, AMTOR. Packet, and facs~mileTransm~ss~on & Reception plus the ability to monitor the new Navtex marlne weather and navigat~onalsystem.. .7 modes in one controller. The PK-232 makes any RS-232 compatiblecomputerorterminal thecompleteamateurdigital operating position. All decoding, signal processing and protocol software is on ROM. Only a simple terminal program (like those used with telephone modems) is required to interface the PK-232 with your computer.

Here's a value you can't beat . .the basic 8088 104 Keyboard An excellent starter for both packet and busrness at the Monochrome monitor incredibly low prlce of $595. Or for anyone requlrlng an extremely h~ghspeed unlt at a com ar~blylow prlce ask us 4 64OKofRAM about the models 80286 and 803l6. They are perfect for 360K floppy buslness or data communlcatlons and we can configure 2 serial 1 parallelport them to your requirements. And, of course, these systems are covered by a one year warranty.

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v 114 34 Ham Radio/June 1990 Ham Radlo Techniaues

By Bill Or6 WGSAI It would be helpful if the forthcoming WARC were to examine some of the gross abuses occurring in the HF WARC broadcast spectrum. If these bands In 1992, if all goes as planned, a World were be~ngused properly, there would Administrative Radio Conference be plenty of room for all. Spectrum (WARC) will convene in Geneva, Swit- conservation would help to take the zerland. The Amateur Radio bands will heat off the Amateur bands. be examined closely once again by the From a technical viewpoint, the participants, some of whom view the same can be said of the fixed service Amateur frequencies as a happy hunt- bands. More and more communicators ing ground. We were lucky at the last are using satellite transmission. In the WARC. We retained our traditional HF return on the investment of these broad- meantime, time-honored marine CW bands and gained new narrow bands casts. It must be very low. Regardless, stations (like Radio San Francisco, at 10, 17, and 24 MHz. Good long many countries (including the United KFS) are on the verge of closing down. range planning by the United States States) are upgrading their shortwave SSB has supplanted AM; SITOR is delegates and observers, in coopera- facilities with more power, bigger rapidly replacing FSK and CW. This tion with delegates from other coun- antennas, and better studios. means there's more space available in tries, brought us this triumph. No doubt there will be enormous the fixed service and maritime bands. Now we must run the gauntlet of a pressure at WARC '92 for an expan- And, if all goes well, the military require- new conference held during perplex- sion of the present shortwave broad- mentfor HFradioshoulddecreaseasthe ing and rapidly changing times. Our cast bands to accommodate all the armed forces of the world shrink! technical and political worlds are in new voices and provide more elbow Great opportunities for Amateur flux, and this situation raises some room. I think they should do the Radio lie ahead if our representatives important questions. In view of the reverse. Let's clean up the present prepare themselves beforehand and amazing changes in Eastern Europe, bands by cutting down on repetitive work in harmonious conjunction with are the costly, spectrum-consuming broadcasts! Eliminate multiple trans- Amateur Radio societies around the shortwave broadcasts of special missions of the same program in a par- world to establish astrong and realistic interest stations like Radio Free Europe ticular band. Place a cap on the power position. Of course, this means we and Radio Liberty still necessarp Are war. Treat the bands as a valuable must get our own house in order! the propaganda broadcasts of Radio resource instead of a propaganda Yes, the next year or so will certainly be Moscow, Radio "Free" Cuba, and dumping ground. interesting as far as the future of numerous other countries relevant? During the cold war decades, the Amateur Radio is concerned. Stay Sadly, the "radio" portion of the cold world grew tired of propaganda. Most tuned. war has been growing instead of people arenY fooled by what they hear shrinking. Many countries are, or will on the shortwave radio. For years, The Yagi soon be, on the air with megawatt HF casual listeners were amused by the ON4UN broadcast transmitters operating into "news" broadcasts from Radio design program huge curtain arrays. Transmissions are Moscow. Megawatts of energy, large Computers can be a great help in made around the clock in many for- transmitting facilities, and a huge staff determining the electrical and physical eign languages. Radio Peking, for were committed to these broadcasts. properties of an antenna. In past example, broadcasts to the world in They went on 24 hours a day, 365 days columns I've discussed the antenna over 40 languages including Serbo- a year, blanketing the world with bom- programs available from Brian Beezley, Croatian, Urdu, and Bulgarian. I bast in every known language. Any K6STI. These are user friendly deriva- wonder what common bond the educated listener knew he was hearing tives of MININEC, a program developed speakers of these languages have with hogwash. For years the Pacific Service at the Naval Ocean Systems Center at China that would induce them to listen of Radio Moscow bruised the ears of Point L.oma, California. The K6STI pro- to these broadcasts? It seems to me listeners in the Americas with broad- grams provide modeling and optimiza- that many countries squander casts of such poor audio quality and tion facilities that are very helpful to the megawatts of valuable energy broad- high distortion that the programming antenna designer. They also include a casting their views to the world. was virtually unintelligible. Yet the small library of predesigned antennas. The upshot of all this is that the inter- broadcasts went on. It seemed the Johri Devoldere, ON4UN, and Roger national shortwave broadcast bands desire was to transmit something - Vermet, ONGWU, have compiled a are a mess. The stations are layers anything - whether the transmission software package which takes you deep! It's interesting to contemplate the was readable or not. through all the aspects of Yagi design

Ham Radio/June 1990 35 ...... DESIGN # 10 ELEMENTS: 3 NAME: FREDA ROOM: 0.249 WVL-

FRED. GAIN F/B RESIST RECSCT. SWR FOM ------1.5% 7.4 20.5 28.8 -12.6 1.5 9.0 ANT. 9 = 14 -1.0% 7.4 23.4 29.1 -9.0 1.3 9. 4 -0.5% 7.4 23.9 28.8 -5.3 1.1 9. 7 SWR BW :> 3 % 0.0% 7.5 24.4 28 .(1) -1.4 1 .(1) '3 .'3 +0.5% 7.5 25.4 26.8 2.8 1.2 9.9 F/k BW > 3 % .,C .- +I.C)% 7.6 22.8 LJ. L 7.5 1.4 9. 5 +1.5% 7.7 13.2 23.4 12.5 ...... 1.8 8.9

1 1 ELEMENT LENGTH POSITION 8 PHYSICAL BOOMLENGTH a ------I------: REFLECTOR 0.510217 -. 105595 : 28Mhz -> 2.63 m. OR 8.6 ft : DRIV. EL. 0.483032 0.000000 : 24 Mhz -> 2.99 m. OR 9.8 ft I DIR # 1 0.452359 0.143370 : 21 Mhz -> 3.52 m. OR 11.5 ft I DIR # 2 0. 00Q000 0. 00000(3 : 18 Mhz -> 4.12 m. OR 13.5 ft : DIR # 3 0.000000 0.000000 1 14 Mhz ->. 5.27 m. OR 17.3 ft : DIR # 4 0.000000 0.000000 : 10 Mhz -> 7.37 m. OR 24.2 ft : 1 7 Mhz -::. 10.51 m. OR 34.5 ft : --_-_------.------EL. LENGTHS ARE FOR EL. D IAM. OF .00 10527 WAVELENGTHS C 7/8 INCH ON 14.2 MHz 1) . S = SELECT THIS DESIGN C: = CONTINUE M = MENU

The "generic" design for a three-element beam. Length and position of the elements are given in wavelengths. Gain (dBi), front-to-back ratio, and input impedance are provided over a band of frequencies.

- electrical as well as mechanical. base, you can quickly find an antenna The ON4UN database This is not strictly a modeling program; that will fill your needs. It's both instructive and entertaining it consists of a comprehensive data- If you want to add your own design to browse through the ON4UN pro- base of 100 different HF Yagis from two to the existing database, the program gram database. Each antenna has to six elements. There are Yagis for provides an empty database with room been given a woman's name. 1 like every application: wideband, narrow- for up to 100 records. That should CYBlL (Design no. 15) for 20 meters. band, gain optimized, front to back satisfy even the most unusual antenna It offers a very good FIB ratio and optimized, and so on. requirements! excellent gain. The antenna fits on a Working from the program's main Once you've selected a design, the 20-foot boom and can be considered menu, you can browse through the program provides the dimensions for a classic design which can be scaled database and select a Yagi design that untapered ('Qeneric") elements (see to other bands (see Figure 2). meets your needs. You can specify Figure 1). The program also provides The 10-meter contest operator may maximum boom length, minimum gain, a tapering schedule and matching wish to choose JOAN (Design no. 95), or other parameters. You can modify data for gamma, omega, and hairpin a wide-spaced (1.03 wavelength), six- the design as you see fit. As an aid, a matches. element stagger-tuned beam. This well-written program outline is provided antenna provides 11.6-dBi gain with an on the disk. Mechanical design of excellent FIB ratio. It covers the range the Yagi 28.0 to 28.75 with less than 2:l SWR. The Figure of Merit A novel and valuable section of the Not bad! In addition to the usual parameters, ON4UN program concerns Yagi Summary the ON4UN program expresses each mechanical aspects. Element strength, Yagi design in terms of a Figure of boom strength, weight and balance, All in all, the ON4UN program is a Merit (FOM) which combines the main wind loading and torque moment can valuable tool for the Amateur interested performance of a Yagi in one figure: be determined easily for a given In antenna performance. The YAGl design. All of these characteristics are DESIGN software comes in MS-DOS FOM = gain (dBi) + 0.1 x (worst illustrated in the program for Design format. For more information contact lobe front to back) - (I - SWR) no. 10: a three-element 40-meter beam either John Devoldere, Poelstraat The Figure of Merit is an deal tool which provides better than 7-dBi gain 215, 89220 Merelbeke, Belgium; B.W. for rapidly evaluating the overall (gain, and 20 dB or more FIB ratio over the Jorden, K7KI, 6861 Kenanna Place, FIB, and SWR) bandwidth performance entire band. The boom length is only Tucson, Arizona 85704; or HAM of a Yagi. Armed with the FOM of the 24.5 feet! SWR across the 40-meter RADIO Bookstore, Greenville, New various antennas in the ON4UN data- band is less than 1.8:1. Hampshire 03048-0498.

36 Ham Radio/June 1990 DESIGN # 15 ELEMENTS: 3 NAME: CYEIL BOOM: 0.288 WVL ------.---

-----FREG!. GAIN---- F/B- - - RESIST------REACT.------SWR--- FOM--- " ANT. (5! = 18 -1.5% 7.4 23.8 36.0 -15.3 1.6 .L -1.0% 7.5 24.5 34.1 -11.2 1.4 '3. 5 -0.5% 7.6 25.2 31.8 -6.7 1.2 '3 .9 SWF: BW > 3 % 0.0% 7.7 26.1 29.3 -1.6 1 .0 1Q .3 +0.5% 7.8 21.9 26.6 4 .0 1.3 9. 7 F/B BW :';. 3 % +1 .O% 7.9 18.4 23. -3 10. 1 1.6 9.1 +1.5% 8.0 15.6 21.2 16. 9 ...... 2.2 8.4

ELEMENT LENGTH POSITI ON PHYSICAL BOOMLENGTH # ------I------; REFLECTOR 0.512185 - .I56638 : 28 Mhz -> 3.04 m. OR 10.0 ft I DRIV. EL. 0.485794 (:I .(:)lj(:)l:)QO 1 24 Mhz -> 3.46 m. OF: 11.3 ft I DIR # 1 0.458877 0.131112 1 21 Mhz -> 4.07 m. OR 13.3 ft I DIR # 2 0 .000000 (j. (:)(:)1>000 : 18 Mhz -> 4.76 m. OR 15.6 ft 1 DIR # 3 0.000000 0 .OC>0000 1 14 Mhz -> 6.09 m. OR 20.0 ft : DIP # 4 0.600000 0. 000(j(j0 1 10 Mhz -:. 8.52 m. OR 28.0 ft I : 7 Mhz -:>. 12.15 m. OR 34.9 ft I ------.------EL. LENGTHS ARE FOR EL. DIAM. OF .0010527 WWELENGTHS (7/8 INCH ON 14.2 MHz). S = SELECT THIS DESIGN C = CONTINUE M = MENU

I Three-element Yagi for 20 meters. Boom length is 20 feet. Design may be scaled to other bands by program.

...... DESIGN # 14 ELEMENTS: 3 NAME I CHRISTY BOOM: 0.288 WVL

FEEQ. GO IN F/B RESIST REACT. SWR FOM--- 9.0 ANT. Q = 11 9.2 9.3, SWR BW > 3 % 9.7 9.7 F/B BW > 3 % 9. 6 9.1

I I ELEMENT LENGTH POSITION I PHYSICAL BOOMLENGTH 8 ------:------I REFLECTOR 0.514726 - .I65057 I 28 Mhz -> 3.04 m. OR 10.0 ft I DRIV. EL. 0.487664 0.000000 : 24 Mhz -> 3.46 m. OR 11.3 ft 1 DIR # 1 0.454808 0.122693 : 21 Mhz -> 4.07 m. OR 13.3 ft : DIH # 2 0.000000 0.000000 1 18 Mhz -> 4.76 m. OR 15.6 ft I DIR # 3 0.000000 0.000000 1 14 Mhz. ->. 6.09 m. OR 20.0 ft : DIR # 4 0.000000 0.000000 : 10 Mhz -> 8.52 m. OR 28.0 ft : 1 7 Mhz -> 12.15 m. OR 39.9 ft : ------,------EL. LENGTHS ARE FOR EL. DIAM. OF .0010527 WAVELENGTHS (7/8 INCH ON 14.2 MHz:). S = SELECT THIS DESIGN C = CONTINUE M = MENU

- - - Design no. 14 covers lower half of 10-meter band with low SWR (see Figure 6).

Ham Radio/June 1990 37 ...... DESIGN # 14 NAME: CHRISTY ELEMENTS = 3 FREQ. = 28.5 MHz WAVEL. : 10.5133 m. BOOM: 3.03mor 9.93 ft DRIVEN ELEMENT REACTANCE= -2 uhm.

ELEMENT/POSITION CENTIMETERS INCHES WAVELENGTHS

POSITION REFLECTOR -173.6 -68.4 -. 165057 LENGTH REFLECTOR 544.4 214.3 0.517526 POSITION DRIV. ELEM. 0.0 0. 0 0. 000(:)00 LENGTH DRIV. ELEM. 511.1 201.2 (3.485876 POSITION DIR # 1 129.1 St:). 8 (3. 122693 LENGTH DIR # 1 471.5 185.6 (3.448200 I THESE LENGTHS ARE FOR A CONSTANT DIAMETER OF 7/8 INCH OR 2.2225 CM. I I 1=MENU 2=FREQ. CHANGE 3=TAPER 4=MATCH 5=DESIGN 6=CHANGE DR. EL I Program provides element length and boom position. Next step is to determine effect of tapered element (about 1 inch).

A three-element Yagi for 10-meter DX Last month's column featured a GAMMA MATCH DESIGN wideband Yagi that covered the whole 10-meter band. It provided moderate ------INPUT DATA gain and good front-to-back ratio. For DESIGN FREQUENCY : 28.5 MHz. the serious DXer, the lower portion of FEEDLINE IMPEDANCE : 50 ohm. the band holds the greatest interest ANTENNA POWER : 1200 WATT. Z-ANT RESISTIVE PQRT : 38.30 ohm. and Design no. 14 (CHRISTY) in the Z-ANT REACTIVE PART : -2.00 ohm. ON4UN program provides an ideal ELEMENT DIAMETER : .875 Yagi beam (Figure 3) for this type of GAMMA ROD DIbMETER : .375 STEP UP RATIO = 5.91 operation. Gain is 7.3 dBi with an FIB SPACING (CENTER TO CENTER) : 3 ratio of 38 dB at the design frequency RESULTS of 28.5 MHz. The design requires a ------10-foot boom (Figure 4). ' GAMMA ROD LENGTH : 54.0 cm DR 21.3 inch. SERIES CAPbCITOR : 93 pF. Elements are mounted above the VOLTAGE ACROSS SERIES CAPACITOR : 276 Volts. boom by means of a flat plate meas- CURRENT THROUGH SERIES CAPACITOR : 4.9 Amp. uring 6 x 2 inches; U bolts hold the I I element to the plate and the plate to After taper is determined, program provides data for gamma match, including voltage and the boom. The elements are made of current rating of series capacitor. 718 and 314-inch tubing with a wall thickness of 0.058 inch. The elements are telescoping. The slight degree of taper increases the element length 1 inch from the generic design. Errata The Dead Band Quiz A gamma matching section is used, In my March column, my post office K4COF proposed the following: Can as shown in Figure 5. The gamma is box was given as 7805. The correct the three hands of a conventional ana- made of an aluminum tube. The center address is Box 7508, Menlo Park, log clock ever trisect the circle? In a conductor of RG-81U is inserted into California 94025. nutshell, for an ideal analog clock (that the tube to form the gamma capacitor. Also in March, I stated that the radi- is, one where each hand movescontinu- The match is excellent (see Figure ation resistance of a folded Marconi ously and uniformly), the answer is no. 6).SWR at 28 MHz is 1.35, at 28.5 MHz was four times that of a single-wire If the hands are detented, KABPGA it's unity, and at 28.9 MHz it's 1.65. The Marconi. This is incorrect; the radiation points out that two 'bbvious" solutions FIB ratio is better than 21 dB over this resistance of the two antennas is the are 4:00:40 and 8:00:20. WD8KBW fol- frequency range, peaking at 38 dB at same. The feedpoint impedance of the lows up with the statement that there the design frequency. folded Marconi, however, is four times are 22 non-integer solutions; W0NI You say you'd like a bigger beam that of the single wire equivalent. says one of these is 9:05:2524... hours with more gain? Just look in the Thanks to the many sharp-eyed with only a 0.172-degree error in the ON4UN library and make your choice! readers who caught these goofs! second hand.

38 Ham Radio/June 1990 DESIGN # 14 GAMMA MATCH ------.------FREQ. DIFF (%I) -1.5% - 1 .0% -0. 5% 0. 0% +Q. 5% + 1. 0% +l.5%

FREOUENCY 28.073 28.2 15 28.358 28.5 28.643 28.785 28. '328 ___-______------.------,------.--.- !%(ANTI 44. 6 42.9 30. 7 38.3 35.5 32.6 29.6 X (ANT:) -13. 30 -10. 00 -6.20 -2.00 2.60 7. 80 13.60 -_--__---______------.------FI C OUT :I 57. '30 56.40 58.50 50 .(50 44.80 38. 30 31 .30 X (:OUT:) 13. 3:) 9.10 -10.80 0 .00 -3 . 9(:) -6. 40 -7. 2(:) ------_-----__------.------SWR_-_------___-______------1.33 1.23 1-29 1 . (:I(:) 1.15 1.35 1.65

Program provides gamma match specifics at seven frequencies, plus antenna impedance data.

AE2P and George McHugh indicate in solutions and comments personally, W08E; Wayne Cooper, AG4R; Dan that 2:54:33 and 9:05:27 are close. but I appreciate the time and effort put Hopper, K9WEK; Mike McDermott; KM4AS wonders about 11:38:10.9090... into all the replies. I read and enjoyed Ron Romer, NIBHE; Bill Shanney, and 12:21:49.0909... . each one! KJGGR; Bob McGraw, W2LYH; Art KBYXE, KEGVK, and others sent a To date, the following have responded Lashbrook, WXGL; Al Weller, BASIC program which lists all the per- to this quiz: Jay Harvey, KABPGA; Paul WD8KBW; Tim Bratton, K5RA; John mutations and combinations of clock Bunnell, KEGVK; Stan Kadron, Bellah, KBYXE; Bryan Suits, WB8WKN; hands and the error in angularity of a W4UGW; George McHugh; Franklin Don Miller, KM4AS; and Ted Kroener, large number of approximate clock Antonio, NGNKF; John Fowler, AASHR; KAIPL. valuesthat comeclose, but aren't exact. Les Moskowitz, AE2P; Dave Roberts, I can't thank each reader who sent WONT; Paul Lalli, AA5AN; Irene Kott, Ampire Mastmounted RF or Coax switched GaAs fet WRITTEN TEST STUDY GUIDES Preamplifiers. All word-for-wordquestions, multiple choices. . . answers. Choose Novice, Technician, General, Helical filtered preamps for out of band Advanced or Extra Class Answer explanations rejection supplied1 2 meter-19db gain .75db nose figure $4.95 Each verslon $1.50 shlpplng. + handles 160 watts transmitted power. All flw manuals: $22.95 postpald. OR COLLECT OLD RADIOS, YOU NEED ... 70cm-16db gain .75db noise figure HAM RADIO Q&A MANUAL handles 100 watts transmitted power. All 1,932 questions, multiple choices and answers found in every ham license exam, Novice through ANTIQUE RADIO CLASSIFIED Model 146 covers entire 2 meter band Extra Class. FREE SAMPLE COPY! RF switched 13-20VDC $9.95 Shlpped poatpald. Antique Radio's Largest Monthly Magazlne Model 1460s covers a 3db bw of 1.4 mhz MORSE CODE TEST PREPARATION Ciasslfieds -Ads for Parts & Services Model 146CP, 1460SCP, and 160cp Set contains two 2-hr. cassette tapes Articles - Auction Prices-Flea Market Info. powered with 12vcd thru coax Code Teacher, 0-5 WPM $9.95 Also: Early TV, Ham Equip., Books, Telegraph, Model 160 covers 149-174mhz * no helical General Code, 3-15 WPM $9.95 filter Extra Code, 12-21 WPM $9.95 Art Deco, 40's & 50's Radios & more... Plus $1.50 shlpplng per set. Free 20-word adeach month. Don't mlss out! Model 440 tunable from 420-450mhz lOmhz bandpass RF switched 132vdc All ManualslCode Tapes: $49.95 6-Month Trial - $11. * New sport 97 Ham Rules: $ 2.95 1-Year: $20 ($30 by 1st Class) Model 440cp powered with 12vdc thru coax Order shipped same day receivedl Foreign by air -Canada: $32; Mexico: 530; Other: 560. Models 146's and 160 $179 Credit card phone orders: 10 a.m. - 2 p.m. A.R.C., P.O. Box 802-A5, Carlisle, MA 01741 Models 440's $189 W5YI MARKETING fl 115 Shipping for 1 unit - $5.00 P.O. Box #565101 - Dallas, TX 75356 Each additional unit - $2.50 Tel: (817) 461-6443 - 24 hours Ampire Inc. 10240 Nathan Lane Maple Grove, MN 55369 116 (612) 425-m~

Ham Radio/June 7990 39 VARACTOR DIODES FROM RECTIFIERS A new application for rectifier diodes

Hugh Wells, WGWTU, 1411 18th Street, Manhattan Beach, California 90266

any circuit applications, like frequency syn- Experimental results thesizers and RF resonators, require varactor Because rectifier diodes weren't designed for varactor diodes for tuning. The name varactor comes applications, the capacitance value tends to vary somewhat from a combination of words like voltage-variablecapacitor from one device of a given type to another. But sufficient and voltage-reactance diode. Varactor diodes, also called similarity exists to satisfy most Amateur applications. As varicaps, provide remote tuning capability through a volt- expected, point contact diodes exhibited a lower value of age change as opposed to the mechanical movement of capacitance than diffused junction diodes. Point contact a variable capacitor. diodes also have a smaller percentage of capacitance value Unfortunately, varactor diodes aren't always easy to find. change for a given applied voltage range. Table 1 shows But it occurred to me that rectifier diodes might work as sub- the values obtained from samples of various diodes. I stitutes. To find out, I set up an experiment to classify various observed that a minimum voltage from 0.5 to 1 volt was diodes for capacitance as a function of applied voltage. required for the diode to start acting like a capacitor. Below the minimum voltage value the diode dissipation was high, How they work but decreased as the voltage was increased. As the applied When a diode is made, a conduction barrier is formed voltage was increased, a value was reached where the at the junction of its P and N materials. This barrier is called capacitance stopped decreasing, as if saturation had the depletion layer. Applying voltage to the junction causes occurred. I met the objective for characterization by limit- the barrier to narrow or widen, depending upon the polarity ing the experiment b a maximum of 16 volts. However, a and magnitude of the applied voltage. This voltage applica- higher voltage might have provided some additional data. tionis referred to as forward and reverse bias. With forward The voltage range obtained for controlling the capacitance bias the barrier narrows, allowing conduction to take place. change seemed to be independent of the peak reverse volt- When the bias is reversed, the barrier widens and serves age (PRV) value of the diode. as an insulator. The percentage of barrier movement under voltage control is predominately a function of material Measurement method doping. Rectifier diodes are heavily doped to enhance a Measuring low picofarad values of capacitance with high forward current; this results in small reverse-biased accuracy is difficult, particularily when the capacitance barrier width changes. value being measured is nearly equal to the stray circuit Widening the barrier produces an effect which is similar capacitance value. I attached a power supply to the diode to that achieved by increasing the spacing between plates to provide the DC bias needed for varying the capacitance. of a capacitor - the capacitance value is reduced. Reverse- My objective was to identify obtainable capacitance values biased diodes exhibit a decrease in capacitance between and range as a function of the applied voltage. their terminals as the applied voltage is increased. I used both digital and analog capacitance meters to

40 Ham Radio/June 1990 Diode capacitance values in pF. Voltage, volts 3 4 Diode Capacitance, pF 1N34 1N92 1N295 1N305 1N457 1N485A 1N538 1N540 1N645 IN914 IN1692 1N 1763(RAY) 1N1763(RCA) 1N2069 1N2071 1N4001 1N4002 1N4003 1N4004 1N4007 IN4148 IN5415 2E4 SR3011

no current, the diode would have the same voltage across its terminals as the voltage measured at the power supply. CAPACITANCE METER All measurements were made below 1 MHz.

Observations For VHF and UHF applications, it's desirable to test the diode's performance at the application frequency. I have MYLAR noted experimentally that some diodes have a dissipation factor high enough to prevent their use in UHF applications. DIODE UNDER TEST Also, the figure of merit (Q) of rectifier diodes doesn't seem to be as high as commercial varactor devices. Although I didn't test it as part of this experiment, I assume that the base-collector junction of a UHF transistor would exhibit suitable varactor characteristics for UHF applications. The applied RF voltage from a resonant circuit should - + be only a small percentage of the varactor's DC control volt- VARIABLE-VOLTAGE SOURCE age. Large RF voltage swings could cause the diode to conduct. This would result in waveform distortion and Q loss. Diode capacitance test circuit. C, is a CpF ceramic reference cape- Therefore, when used in a resonant circuit, the RF voltage cltor. applied to the diode would have to be expressed as a negative ratio from that on the inductor. A series-connected capacitor with a value nearly equal to the varactor will correlate the data. I chose a 5-pF ceramic capacitor as a provide an approximate voltage ratio of 211. Zener diodes reference. My purpose here was to validate my measure- operated below their zerler voltage value should exhibit ment technique. The test circuit IS shown in Figure 1. I used varactor characteristics. a 0.01-@Fmylar capacitor between one diode lead and the I couldn't measure the junction capacitance of microwave meter terminal to provide DC isolation between diode and diodes like the 1N82A. The junction appeared to be con- meter. Two 100-k carbon resistors provided capacitance iso- ducting as a result of the AC signal from the capacitance lation and DC from the power supply. Higher resistance meter, whether or not reverse DC bias was applied. 5

Ham Radio/June 1990 41

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Ham Radio/June 1990 43 PRECISION CRYS FREQUENCY CHECKER

By Michael A. Covington, N4TM1, 285 Saint George Drive, Athens, Georgia 30606

ost crystal checkers perform a simple "yeslno" quality test or may give a relative indication of activity I've designed one that teams UD with a frequency counter to give precise frequency readings under three different load capacitances: series, 20 pF, and 32 pF. It can also measure inductance, though with a bit less accuracy. And even without the frequency counter, this checker will tell you whether or not a crystal oscillates. This project really is a "weekender." You can find all the parts at Radio Shack, if they're not already in your junkbox. Thecircuit isacolpitts oscillator (see Figure 1); capacitors

- 4 LED1 C I l8pF SZ ONrnFF \I a- /I I.. s 1 a- 1"

* - XTAL UNDER 4 TEST

Circuit is a Colpitts oscillator with buffer amplifier.

44 Ham Radio/June 1990 TO C1. C2. AND S1

Parts placement diagram. View is from top (component side).

OUT ON 0 sC.. ..,. CKVSTLL TFSTCR 1 N4TMI

Circuit board Is half of a ready-made board from Radio Shack (RS no. 276-159A). were chosen to work with most crystals from 2 to 20 MHz. To test a coil, measure resonant frequency with 32 pF. 01 oscillates and Q2 buffers its output. For the yeslno test, Dl and 03 rectify the signal from the oscillator and use it to light an LED. It's normal for this LED to dim or go out when there's a load (like a frequency counter) connected Photo A). The tester is housed in a BakeliteTMbox with a to the output jack. metal front. For reliable measurements, keep leads to S1 When setting the load capacitance, the SPDT center-off and the crystal as short as possible. Use alligator clips as switch S1 lets you connect the crystal directly to the oscillator, a universal low capacitance crystal socket. through an 18-pFcapacitor,or through parallel 18 and 10-pF It's easy to test a crystal. Simply clip it in place, hook up capacitors. Allowing for 2 to 4 pF of stray capacitance, this the frequency counter, turn on the tester, and flip S1 to find givesloadcapacitances near the nominal 20 and 32 pF. The out wh~chload capacitance gives the correct frequency. direct connection gives a high load capacitance that puts This procedure also tells you how much the crystal can be the crystal very close to serles resonance. "pulled" by changing the capacitance. The 20-pF load gives Most of the circuit is compactly built on half a Radio the highest frequency; the series connection gives the Shack 276-159A printed circuit board (see Figure 2 and lowest. Overtone crystals will oscillate at the fundamental

Ham Rad~o/June1990 45 Fnq. 1 dB Rocelvm Range N.F. Qaln Comp. D.rfce Onlv (MHz) (dB) (dB) (dBm) TYP Prim P28VD DGFET PWVD DGFET PSOVDG GaAsFET Pl44VD DGFET DGFET GaAsFET DGFET DGFET GaAsFET Elpolar Elpolar GaAsFET

Inllne (IIawllched) SP28VD 2530 DGFET SPWVD 5054 DGFET SPWVDG 50.54 GaAsFET SP144VD 144.148 DGFET SP144VDA 144.148 DGFET SP144VDG 144.148 GaAsFET SP220VD 220225 DGFET SP220VDA 220-225 DGFET SP220VDG 220-225 GaAsFET SP432VD 420.450 Elpolar SP432VDA 420-450 Elpolar SP432VDG 420-450 GaAsFET

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VUIW-10 49 RF ~hh...... I1.m . 56-IW-64- 1. T.rnt. 84...... 1 .I0 ...... I,m..) Brordbd HF Tr.n.Iamr...... 8 1.m AV.OI.~* ,- bi~or ~dlt..t.r I 1- ...... ,s s.00 ~ddII so r- ,h~,,#q 4m. rlwwMrm..*n.n4.h..,ulrrrH.CulmuW.l. BUCKMASTER PUBLISHING Route 3. Box 56 Mlneral. Virginia 23117 7031894.5777 vlsalmc 8001282-5620 The frequency marked on a crystal isn't always the frequency at which it oscillates. The frequency measured by the crystal tester may be different yet, because the tester doesn't operate in the overtone mode. Here are some kinds of common crystals. F refers to the frequency marked on the crystal. Type of Marked Operating Measured Load crystal frequency frequency frequency capacitance (F, MHz) (MHz) (MHz) General 1 to 20 F F Various purpose General Usually purpose series General Usually purpose series C B Series transmit CB Series receive* Scanner Series Scanner Series Scanner Series Scanner Series

'CB receiving crystals are 455 kHz below the designated channel

Capacitors (ceramic disk or polystyrene, 10 volts, *20 percent) C1 18 pF C2 10 pF C3 470 pF C4 100 to 150 pF C5,C6 330 or 470 pF Resistors (118 watt, -t5 or 10 percent) Rl 100,000 ohms R2,R3 1000 ohms R4 270 ohms Semiconductors Ql,Q2,Q3 21113904 (or equlvalent) NPN siilcon transistor Dl IN34 germanium dlode LED1 Llght-emltting dlode Resonant frequency Other 'O $ I0 Inductance (pH) S1 SPOT center-off (three position) switch with 32 pF (MHz) 8 S2 SPST switch 131 9-volt battery Connector and holder for B1 RCA phono jack for output Tko alllgator clips to hold crystal Circuit board (Radio Shack 276-159A) Enclosure

frequency. For instance, a 27-MHz CB crystal oscillates at 9 MHz (see Table 1). Of course, you can use a crystal whose load capacitance is different from that for which it was ground or use an overtone crystal on its fundamental frequency:' You can also test coils. Just connect a coil in place of Computer-generated nomograph converts measured frequency to the crystal, set S1 for a32-pFload, and measurethe frequency inductance. (see Photo 8).Now find the inductance using the nomograph in Figure 3. You may find it more useful to remember the frequency than the inductance. It's the frequency at which the coil will always resonate with a 32-pF capacitor. Bear in mind that this measurement is inexact because the load isn't precisely 32 pF and the internal capacitance of 'Anovertonecrystal osc~llatesnear, but not exactly at, anodd multipleofthefundamentalcut Expect toseeasmall sh~flof several kHzwhenovertonecrystalsareoperated~ntheirfundamentalmode Ed the coil isn't taken into ac:count.

Ham Radio/June 1990 47 Practically S~eaking

d By Joseph J. Carr; K41PV These potentials are essentially "monopolar" with respect to the demonstrator; so no current flow exists. SAFETY Similarly, some of the less prudent STANDDOWN FOR electricians will work a circuit "hot" (without turning off the power), feeling THOSE WHO safe because they take care not to SERVICE ground themselves or in any other way come between the hot wire and HAM GEAR ground, or across two hot wires. Even I think it's agood ideato discussmatters so, this is an extremely unsafe practice of ham radio safety every so often, and must be discouraged at all times! especially as they pertain to equipment (wearing Bermuda shorts) who was In addition to electrical shock, there and antennas. Unfortunately, from time working in his basement and sat on his are other safety concerns you must to time we hear about a fellow Amateur 600-ohm parallel transmission line consider when working with electricity. Radio operator who was killed while while he performed some adjustments. One major problem is fire. Overloaded working on a linear amplifier or install- Unfortunately, he hadn't disconnected or defective electrical circuits can ing an antenna. it from the transmitter. Someone else spark, overheat, andlor cause a fire. A number of years ago, I wrote an accidentally tripped the rig, intending Many fires every year are traced to article on electrical safety for Ham to tune up and go on the air. After the faulty wiring or malfunctioning electri- Radio (before I started writing "Practi- cursing and screaming was over, the cal equipment. cally Speaking").A footnote added by fellow found burns running parallel Electrical faults will also damage the the technical editor indicated that, dur- down the calf of his leg. equipment, the building where it is ing the week he was working on the Macroshock is the type of electrical housed, or other equipment. A short manuscript, he needed to repair a high shock we all must take care to avoid. crrcuit that isnY protected by a fuse may voltage DC power supply. The HV It results from direct contact with an cause more damage in the shorted OUT line got loose, and snapped and electrical source. If you touch the equipment, and may also affect build- barked around on the concrete floor 110-volt AC line while grounded, a very irig wiring and electrical components. like a venomous viper. (Hrnmrn...j ust painful and possibly fatal shock will In extreme cases, a fire may result. where was that safety article?) If you've occur. Macroshock doesnY require the When fuses and circuit breakers aren't seen this material before, please bear conduit of wounds or other breaches used, or are defeated ("penny in the with me. There are many who haven't of the skin to enter the body. fuse box" syndrome), there is a severe read this information. Besides, a review Microshock is a more subtle form of fire hazard and the level of damage of basic safety doesn't hurt anyone. electrical shock, and at one time it done to any equipment involved will (Even the United States Navy staged wasn't even recognized. However, the most certainly increase. a one-day operations standdown for increased use of electrical equipment Less recognized, but nonetheless review of safety matters.) in hospitals during the fifties and six- possible, is the hazard of explosion The electronic equipment related to ties led some authorities to speculate from electrical faults. There are at least ham radio is inherently dangerous. If that as many as 1,200 people a year two mechanisms which can cause it's not used in accordance with some were being accidentally electrocuted explosions of this type. First, an over- basic common sense rules, operation by tiny currents from hospital equipment loaded circuit or electrical component can lead to injury or even death. There that went unnoticed by the medical rnay build up internal pressure (often are three situations to consider: burns, staff. Microshock is electrical shock from gas released when the device is macroshock, and microshock. caused by currents too minute to affect severely overheated) and rupture. High Electrical accident incidents can persons with intact skin, but able to power transformers and the main ripple cause first, second, and third-degree inflict damage if introduced to the body filter capacitors inside high power RF burns. These burns can occur in two through a wound. Microshock isnY nor- amplifiers are types of equipment that ways: from the flash that results when mally a problem for hams. can explode. an electrical arc occurs, or when current For all forms of electrical shock to The second mechanism of explosion flows through body tissue. Any occur, there must be a difference in is sparking that occurs in the presence experienced emergency room physi- electrical potential between two points of flammable gases or vapors. If an cian can testify that ordinary 60-Hz on the body. In other words, two points electrical circuit is disconnected while power can cause burns. RF can also of contact must exist between thevictim operating, or if certain faults exist, then burn you. A physician, who also hap- and the electrical source. That's why a spark may result. If that spark occurs pens to be a ham, once told me that you sometimes see harmless "hair rais- when either flammable gases, oxygen, high power RF burns tend to be more ing" exhibits, where people touch an or vapors (like gasoline and certain serious because they penetrate electrostatic high voltage (>100,000 waxes) are present, then a violent and deeper into the body. I recall one chap volts!) and their hair stands on end. dangerous explosion may result. Note

48 Ham Radio/June 1990 that oxygen isn't flammable itself, but formed by an untrained person. In fact, example, the risks escalate tremen- vigorously promotes burning of other even CPR can't be performed effec- dously when you're sweating and materials. tively by someone who hasn't learned standing in salt water. Besides the obvious danger of the technique. Everyone who works "shrapnel" wounds from the casing of near, on, or around electrical or elec- Is high current at an exploding device, there's also the tronic equipment should learn CPR. low voltage safe? possibility of injury from splattering Teenage and adult family members boiling oil. In addition to the burns it should learn CPR, too. After all, who's I once attended a design review can cause, this oil can be dangerous going to save you if an electrical acci- meeting on a 100-watt commercial for other reasons. Certain older capa- dent occurs at home in your hamshack VHF rnobile transceiver. One design citors and transformers were built using or workshop? The local Red Cross, the specification called for insulation of low PCB oil as an internal coolant. PCB oil Heart Association, some community voltage (28 volts DC), high current (30A) is a potent carcinogen. Do not down- colleges, and most 1oc:al hospitals can DC power supply terminals. One of the play the importance of this statement direct you to certified CPR courses. It's engineers present remarked that - PCB is dangerous stuff! Although impossible to learn CPR from watch- including this specification was like most PCB-bearing electrical devices ing medical shows on TV; get trained asking him to insulate the battery ter- are now out of service, some are still by a knowledgeable instructor! minals of his car. His comment implied around. Take care when handling that low voltage can never hurt you. older equipment. Be especially suspi- How much current is fatal? There are two false premises at work cious of elderly high power RF ampli- I once worked in a hospital elec- in his opinion. fiers. Should you find one of these tronics laboratory. One day I heard an First, although low voltage, high cur- devices, it would be a good idea to ask intern claim that the 1'10 volts AC from rent points rarely cause electrical a competent person to dispose of the a wall socket wasn't dangerous. Appar- shock., it's possible for a dangerous equipment. A PCB spill can close a ently he was told in medical school that shock to occur when the person has building until a proper cleanup routine it's not the voltage that kills; it's the cur- a very low electrical skin resistance is completed; this can take a long time. rent. I asked the doctor if he had ever (very sweaty) or an open wound. I Once when I publisheda PCB warning, heard of Ohm's law. According to know of an electronics technician who a fellow wrote to me claiming the Ohm's law, the current is the quotient was injured severely when he cut him- problem was overblown. I'll leave it to of voltage and resistance, or I = EIR. self on a +5 volts DC, 30-A computer the experts; they still classify PCBs as It seems that doctor wasn't aware of power supply terminal. Although this dangerous. this formula. The 110 volts AC available case didn't result in electroction, a What to do for the victim in residential wall sockets is the most large amount of current flowed in his common cause of electrocution in the arm, causing severe pain and some of an electrical shock United States. Also, medical studies physical damage. Death by electrical shock often reveal that the 50 to 60-Hz frequency Second, high current is extremely occurs as a result of a phenomena used in AC power di:;tribution almost dangerous if you are wearing jewelry! called ventricular fibrillation (V.Fib.). worldwide is the most dangerous A two-way radio repair shop once used This is an arrhythmic heartbeat; the range of frequencies. 12-volt batteries and battery chargers heart merely quivers instead of beat- Higher and lower AC frequencies for the troubleshooting bench supply ing. Unfortunately, a heart in V.Fib. is are less dangerous than 60-Hz AC, but for mobile service. A technician work- incapable of sustaining its blood- they're not safe! Medical experts ing cbn the battery rack dropped a pumping effectiveness, so the victim who've studied electrical shock say the wrench, and it fell onto the battery dies within a few minutes - unless a killing factor is current density in a cer- making contact from (-)to (+) through person trained in cardiopulmonary tain area of the right atrium of the heart his watchband. The large current resuscitation (CPR) is nearby. called the sinoatrial node. Any flow of turned the watchband red hot, giving Before you aid a victim of electrical current through the body which him some serious second and third- shock, be sure that he is no longer in causes a high level of current to flow degree burns. Don't assume that low contact with the current, or that the cur- in that section of the heart can induce voltage, high current power supplies rent is turned off! Otherwrse, when you fatal V.Fib. In general, the following are harmless! touch him to administer a~d,you will rules of thumb are accepted for limb also become a victim! contact electrtical shocks through Mechanisms of As soon as the victim is clear of the intact skin (macroshock): electrical shock electrical current, yell for help and initi- 1 to 5 mA Level of perception To raise your consciousness about ate CPR. CPR won't bring him out of 10 mA Level of pain how shock can occur, look at scenarios V.Fib., but it will provide life support 100 mA Severe muscular of electrical shock that might affect until properly equipped and trained contraction hams. Figure 1 shows the direct medical personnel can be summoned. 100 to 300 mA Electrocution aproach to fatal electrical shock. They'll use a defibrillator to shock the Keep in mind that these figures are Imagine that you're grounded through victim's heart back into correct rhythm. approximations and are not to be conductive shoes and you touch an They'll also use drugs and intravenous accepted as guidelines to approximate electrically hot point. You needn't be (IV) solutions to re-establish his body's 'hssumed risk." Under certain circum- outdoors to be affected. A concrete balance. stances, death can occur with con- garage, shop, or basement floor is a None of these actions can be per- siderably lower levels of current. For resonably good conductor, as are wet

Ham RadiolJune 1990 49 ladders are made of wood or other nonconductive material - not of aluminum like consumer ladders. POWER LINE Some cures for these problems

POWER SUPPLY Figure 4 is a schematic of the usual + lJnited States residential AC electrical HV system. Industrial electrical systems are - a bit different at the service entrance, i but become much like those in Figure 4 when the power is distributed throughout the building. The power c:ompany distributes energy through high voltage lines. When it arrives at a point a short distance from the cus- tomer, it is stepped down in a "pole pig" transformer to 220 volts AC center tapped. The center tap (C.T.) of the 1 transformer secondary is grounded, and therein lies the root of the problem. Shock scenario where a grounded instrument probe creates a path for current. The two ends of the 220-volts AC secondary are brought into the build- leather and some types of rubber ing as a pair of 110-volts AC hot lines. shoes. -fabptng across the two lines produces Figure 2 shows an indirect shock a 220-volts AC outlet; tapping from the scenario that electronics workers POWER ground line (i.e., transformer C.T.) to should always keep in mind. Consider HAND either hot line produces a 110 volts-AC the grounded instrument probe (in this outlet. case an oscilloscope). When you The electrical ground system in the VICTIM'S grasp that probe, you may be BODY IJnited States is ground referenced; grounded through the scope shield that's the problem. The solution is to and the power cord ground conduc- rnake the little local electrical system HAND tor. If you touch a "hot" point, you'll get 'SCOPE non-ground referenced. This is done shocked - and may be killed. PROBE in hospital operating rooms, and in A related scenario is shown In some intensive care units, for patient Figure 3. Here you see an AClDC con- 'SCOPE !safety reasons. It should also be sumer appliance, like a low cost radio implemented on radio service or n/ set. Note that the oscilloscope benches, especially if ACIDC power probe ground is connected to the set Equivalent circuit for Figure 1. :supplies (damnable devices!) are ser- ground, which also happens to be one side of the AC power line. Everything is fine as long as the AC plug is oriented correctly in the wall, and if the wall socket is wired correctly. But if you I-- put the plug into the wall receptacle REVERSED backwards, there will be an explosive POLARITY short circuit which could electrocute the operator. GROUNDED The fatal antenna erection job has contributed to the deaths of many hams. It isn't good practice to erect an antenna near a power line! NEVER! Every year we hear stories of people who were electrocuted when an antenna they were working on fell across the power lines, when they tried to toss a wire antenna over the power line in order to raise the antenna above them, or when a ladder they were using fell across the power lines. These foolish tactics will kill you. Incidentally, this is why OSHA-approved industrial Shock scenario for AClDC power supplies.

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Ham Radio/June 1990 51 It's sometimes recommended that you work on high voltage devices with 220 V AC LlNE your left hand in your pants pocket. HlGH Supposedly, the "left hand to either leg TENSION path" is the most deadly. Even so, working with one hand in your pocket llOV At is awkward. I don't think anyone is able LINE A to work on a circuit safely with just one hand. It's better to use both hands, arrange a safe work environment, and llOV AC 0 = CIRCUIT BREAKER use good techniques. LlNE B What's a safe work environment? It's -- one where the power system is isolated. Residential AC electrical system. The floor should be insulated by a car- ~et,treated masonite, a ~lasticcover, a rubber mat, wooden 'planking, or some other material. Also remember to keep the floor dry. Use an isolation transformer on the workbench for servicing radios. VARIABLE When working on high voltage DC OUTPUT circuits, like those inside linear RF amplifiers, remember that capacitors store electrical charge. All filter capacitors must be discharged manually FIXED OUTPUT after the power is turned off. Also remember that the capacitor must be discharged several times. Even when 5-16 a short circuit is placed across the capacitor terminals, all of the energy is not removed the first time it is dis- Workbench electrical system. charged. Some energy is stored in the dielectric, even after the main charge viced. Figure 5 shows the wiring for equipment on the bench. is dissipated. such a system. Transformer TI is one The circuit breaker or fuse protects How do you short the capacitor ter- of two types of isolation transformer. A the bench equipment and the trans- minals? With a screw driver? With an 1:1 transformer gives a 110-voltsAC iso- former. It's always placed in the hot line, alligator clip lead? No! Use a shorting lated (non-ground referenced) AC line and can also be placed in both lines. stick (Figure 6).Do not make the stick from a 110-voltsAC standard line; a 2:1 However, fuses and circuit breakers out of wood! Use a dielectrically com- transformer does the same thing from should never be placed In the neutral petent plastic material instead. Be sure a 220-volts AC line. line only. The switching shown in to use more than one ground line. If The second transformer, T2, is an Figure 5 breaks both lines. I prefer this one of the lines falls off while you're autotransformer used for varying the approach because hot and neutral working, there will be one or more lines voltage on the AC line. It will typically lines can be reversed accidentally, left to carry off the charge. Be sure to allow you to set the output voltage from leaving you in the position of breaking wear eyeglasses or safety goggles to 90 to 140 volts AC with a 110-volts AC a neutral while the hot line remains line voltage applied. This transformer alive. is used by servlcers to set the voltage higher or lower than normal to check Some general points radio operation or expose problems. on safety If you work on radio transmitters, you There's only one way to ensure that might want to place an electromag- the AC line won't shock you - discon- HIGH DIELECTRIC netic interference (EMI) filter in the line nect it. Make it your practice never to at the points marked "X." The EM1 filter work on equipment that has the plug is an LC-sectionthat attenuates RF, but inserted into. the power outlet. Don't doesn't affect the 60-Hz power. trust switches, fuses, circuit breakers, The "MOV" is a metal oxide varistor. or other people. If someone were to It's used to clip the amplitude of high hand you a pistol, claiming that it was voltage line transients (100 microse- unloaded, the first thing you'd do is WIRES conds or so) that could either damage check it yourself. The same advice or interfere with the operation of the holds true for an electrical connection Capacltor discharge wand.

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fl 109 Ham Radio/June 1990 53 WHY IS THIS TOUGH OLD BIRD STILL prevent eye damage from the flying sparks. THE INDUSTRY STANDARD WATTMETER? The power cord ground is the only ground available to the equipment chassis when you have it running on the bench. This is insufficient for safety. My workbench has a grounded 5116- inch bolt on the back edge. When I work on high power RF equipment. I ground the chassis to that ground point with a heavy cable. Don't over- look this ground. When only the power line ground is used, high power RF Simple. No one's '?ravelswto strange places and can been able to improve cause problems. I recall a time in a on the basic Bird hospital electronics lab when we serv- Model 43 THRULINEm 'directional wattmeter since iced an electrosurgery generator. its inception - not even us.' These devices are high power (500 Hugged, reliable and accurate., watt) 1-MHz (or so) RF power oscillators. (Some of them were spark gap easy to use. With Bird precision "transmitters" as late as the early too, the new 4:IP . or plug-in elements, it .. 1980s!) I forgot the ground rule and measures forward and you can retrofit your reflected CW power trusty Model 43 for it in kicked the "transmit" switch. Bright EieK& about 15 minutes. Con- blue RF sparks flew from every inch of from 10mW to 10,000W, 0.45 to 2,300 MHz, with tact us or your Bird dis- the metal trimmed FormicaTMwork- 5 5% of full-scale tributor for details. bench. Although the sight was spec-

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By Charles J. Michaels, W7XC, 13431 N. 24th Avenue, Phoenix, Arizona 85029

ere's the problem. You've just put a half-wave dipole or greater than for 40 meters at 52 feet, connected 70 feet of RG-213 (50 ohm) coax, and trimmed the antenna to resonance at 7.15 MHz - but the best VSWR you can get is 1.6:1. Although the calculated extra 0.05-dB loss In this case the antenna VSWR is 1.7:1 and, because (above the 0.38-dB calculated matched loss - see Appen- dix A) is negligible, you don't like the VSWR and your trans- 50/ m- = 38.3 ohms ceiver doesn't either. Check the input impedance curve of a half-wave dipole and versus height (0.375 wavelength in this case) in almost any antenna text and you'll find that you should have about 50 = 65.2 ohms 85 ohms for a VSWR of 1.7:l at the antenna, and 1.62:1 through 70 feet of RG-213line (see Appendix 6).What to do? the R2 section must have an impedance of either less than How about a balanced L net at the antenna? Hmm, two 38.3 ohms or greater than 65.2 ohms. RG-11 at 75 ohms coils and a capacitor in a weather protective box. Weight, is standard, so the system is feasible. wind load? To simplify the calculations, normalize the load imped- How about a stub matching system? Gosh, that RG-213 ance RL and XL, and the Z2 impedance to the main line is heavy enough now! impedance Z1 as follows: Or how about a quarter-wave matching section? Let's see, n = Z2/ZI (1 r = RL/Zl (2) 2, = = 450 x 85 = 65.2 ohms x = XL/Z1 (3) Because Z2 is 75 ohms, RL is 85 ohms, XL is zero ohms Sixty-five ohm coax? Not exactly a standard item! (a dipole isa pure resistance at resonance), and Z1 is 50 ohms Is a transmatch the only answer? No! using Equations 1, 2, and 3, n = 75/50 = 1.5, r = 85/50 = 1.7 and x = 0150 = 0. A solution The angular length of section 22, or R2q is calculated as This, and many other matching problems, can often be follows: solved by using a series section transformer. The technique uses a calculated lenath of feedline. 19, removed at a cal-

vide a match tb loadsthat include reactance. ~urthermore, it becomes part of the feedline rather than an addition.

Calculation TRANSCEIVER Use the aforementioned problem as an example. Your first task is to determine feasibility. The R2 section of line 1 I must have a characteristic impedance either less than Series section transformer. 2, is the main-line characteristic impedance. Z, is the matching-section characteristic impedance. See text tor catcolation of z:,, I,, and 1,.

Ham Radio/June 1990 55 RZ0 = arctan B this line. In VHF applications, take extra care to include the where: connector and barrel lengths in the calculations. Other applications This system is applicable to both coaxial and balanced lines. In fact, because a wide range of balanced line impedance is available through your choice of conductor For the examvle: diameter and spacing, balanced lines offer a wide range of matching section parameters. You can also use this system at the sending end, when it may be necessary to match a line of other than the 50 ohms for which your transceiver, VSWR meter, and low pass filter are designed. Appendix A-Loss tatal A trigonometry table of tangents or a scientific calcula- RG-213 at 7.15 MHz has 0.55-dB loss per 100 feet. There- tor indicates that a tangent of 0.842 corresponds to an fore, 70 feet of matched line has 0.7 x 0.55 = 0.38-dB loss. angle of 40.119 This angle is converted to feet of transmis- ,- -u sion line by Equation 5. Loss total =: I0 loglo R' = (2.733 x R0 x Vf)/F (5) where where: B = ]oLmNO I,' = length in feet Lm = loss matched in dB R0 = length in degrees and Vf = velocity factor of line F = frequency in MHz In the example, velocity factor Vf is assumed to be 0.66 for both the RG-213 and RG-11. Quality coax is usually very close to specification. Using Equation 5: where 1'2 = (2.733 x 40.11 x 0.66)/715 = 10.12: or 10' 1.4" St = VSWR at load The angular length of section 11 is calculated as follows: 1,' = arctan A (6) where: r A= (n--;;)B+x r + xnB - 1

For the example, 17

0.441 is the tangent of 23.89 Again using Equation 5, 0.43 - 0.38 = 0.05 additional loss due to 1.7:1 VSWR Rrl = (2.733 x 23.8 x 0.66)/715 = 6', or 6'0" Appendix B-VSWR The design is now complete. Si = VSWR at generator end of line If you find the quotient is negative when calculating B S, = VSWR at load end of line of Equation 4, then Z2 is too close to Z,. This may happen when reactance is present in the load, despite initial indications of feasibility. When calculating A of Equation 6, the result can be a negative number implying a negative angular length. In B = ~OL"/IO Lm = loss matched in dB this case, add 180° to the negative angle to obtain the correct length. s. = B+C Implementation B-C Cut the RG-213 coax line 6' from the antenna and insert a 10' 1.4" length of RG-11 line. You can do th~sneatly with PL-259 connectors and barrels weatherproofed by wrapping the connectors and barrels with RTV compound. If you use connectors and barrels, include their lengths in the 11 and R2 lengths. You may shorten the remaining RG-213 line to the station if you wish, as 10' 1.4" has been added. Because the addition is small, it's probably not worthwhile to shorten VSWR at input to line is 1.62:1

56 Ham RadioNune 1990 current (Ig) was about 2 A. The coun- Cleaning Electronic terpoise capacitance to ground was about 700 pF, and the antenna capac- Hardware itance to ground was about 500 pF. Try Tarn-XTMto clean and brighten tar- Conclusions nished or dirty coaxial connectors and similar electronic hardware. Tarn-X is In the "old days" your antenna claimed to contain acidified thiourea, ammeter was your power meter. You put detergent, and corrosion inhibitors. You up an antenna, connected a ground were higher when using the counter- can find it in department stores. and tuned for maximum antenna cur- poise. The manufacturer recommends wip- rent. If you were "in the chips," you ing Tarn-X on with a cloth or cotton ball, Beverage's system were the proud owner of a thermo- coupled RF ammeter. You proudly told but I've found it effective as a reusable Having permission to operate above dip. Many parts require dipping in your listener, "I'm radiating 1.2 TCA 200 meters, 2BML chose to tune his Tarn-X for only 30 seconds to a minute amps* to my four-wire flat top up 80 flat top on 280 meters (1071 kHz). With feet, OM." This meant you were in and then rinsing in hot water. The rest a fair ground, his measurements can usually be cleaned up with a few between the Ford coil (spark) group, showed a system resistance of around swipes with an old toothbrush or and the guys with a kW or two. When 70 ohms and 0.5-A antenna current. fingernail brush and redipping. you decided to change from an "earth But with the elevated counterpoise I've used this stuff for about 10 years, warmer" ground to a counterpoise, you attached, the system resistance and my first bottle (I have two) is still becarne listed in the "Calls Heard" dropped to 10 ohms! going strong! columns printed by QSTevery month. The ground lead tap on the induc- David McLanahan, WA1FHB For March 1922 they listed six pages tor was adjusted to cancel the capaci- of logged heard or worked stations - tive reactance of the elevated counter- spark or CW. Big DX was here! poise. The inductor was wound, using Going from a good ground to a 318-inch tubing, into a 20-turn 15-inch counterpoise raised your signal about More on diameter coil. Each time an adjustment 10 dB. Adding the 2BML circuit gave was made the system was retuned for you 3 or so more dB. Elevated Radials: input power and frequency. With both Take your pick. Rent a backhoe and H.H. Beverace's 1921 the earth and counterpoise connected, bury a few thousand feet of copper, or a system resistance of 4 ohms and an put up a few elevated radials on 160 counterpoise System antenna current of 8 A was obtained! meters. With 8 A of RF current going into the Bill Orr's November 1989 column in Dave Atkins, WGVX antenna, the counterpoise wire current Ham Radio touched upon the advan- (Ic) was about and the earth ground 'Amps measured by a thermo-couple ammeter Ed taaes of usina elevated radials. This 6 A, rehinded meof an earlier article by H.H. Beverage, ZBML, that appeared in a 1921 issue of an RCA catalog. It described an aerial and counterpoise system, suggested by a Mr. Alexander- son, using a coupled ground wire. Details of 2BML's flat top antenna system of 1921 are shown in Figure 1. Adding this coupled ground wire was the secret to improving antenna AMPS r,CCw,RE efficiency. Most Amateurs, and many fl broadcast stations (KG0 was one of them) were already using the counter- COUNTERPOISE poise at this time. Old boilers, model T cars, and other scrap metal buried 6 feet down served as the only antenna I ground references for many stations L\\\\\\\\\\\\~\Y\\\\S=~ until the elevated counterpoise EARTH GROUND became popular. Besides finding they were 'betting out" better, operators also 2BML "flat-top" antenna system of 1921. Large inductor allowed matching anenna to trans- noticed that their antenna currents mitter and also permitted tuning-out capacitive reactance of counterpoise radial. Ham RadiolJune 7990 57 NEW PRODUCT RLC-6 FEATURES: 3 HUB OR CHAIN LINKS LlNK CW/VOICE ID'ING w S-COM 5K/6K CONNECTION 8 CONNECTS TO MOST ALL REPEATER CONTROLLERS REQUIRES ONLY 3 LOGIC LINES FOR CONTROL 1 MC ONLY $149.95 VISA LED DISPLAY BOARD 519.95 S-COM CABLE 5 9.95 +CONTROLLER LINK COMM SPECIFIC- -- - I I306 SO 20TH BOZEMAN MT 59715 (406) 587-4085 I

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58 Ham Radio/June 1990 Bob Baird, W7CSD, 3740 Summers Lane, Klamath Falls, Oregon 97603

find that the circuit commonly used in commercially built antenna tuners or transmatches leaves something Ito be desired (see Figure 1). Most use a tapped coil and selector switch. This can create problems, because on 10 meters a fraction of a turn on the coil may be critical. TO XMTR TO ANT FEEDER Also, you can't tap much closer than one turn. As compen- sation, the better units use a roller coil for continuoustuning. However, roller coils are expensive. There's another problem with this circuit. It's basically a Popular and effective T match transmatch circuit used by many high pass filter. As Doug DeMaw and Bob Shriner have Amateurs. Although easy to build, this circuit is basically a high pointed out: this sort of matching circuit does nothing for pass design and offers no attenuation of transmitter harmonics. transmitter harmonics! I made note of a similar problem in an L network design some time ago. Older broadcast transmitters used "inductive" neutralization by means of a coil that was a bit too large in series with a large variable capacitor to achieve an effective variable inductor. Roller coils LARGER THAN that operate at 10,000-volts RF or more are hard to come by. The large capacitor gave a small value of X, and con- SMALL XC sequently a small value of IX,, the voltage across the capacitor. This meant that the variable element for the neutrali- X~-X~=X~NET zation process was a reasonably spaced capacitor which EQUIVALENT TO VARIABLE A gave continuous tuning over a limited range (see Figure 2). INDUCTOR OVER LlMlTECl RANGE If you look at Figure 3, you'll notice that the series elements are inductive and the shunt element is capacitive. This is a basic low pass filter which will indeed do some- Making a fixed inductor variable. Capacitor in series with Inductor is equal to smaller value inductor that is variable over a limited range. thing for any harmonics present. Broadcast stations have In practice a larger value inductor than the design calls for would been using this kind of matching network for years, for be needed to compensate. exactly the same reason. But you need two roller coils isolated from ground to build this circuit, and this would be expensive for the average ham. How to do it inexpensively Suppose you were to replace the top of the '7" roller coils with tapped coils and seriescapacitors, giving a net variable TO XMTR TO ANT L. The result is shown in Figure 4. Some time ago, I saw a nice forty-turn 2-inch diameter coil for a bargain price.

I bought it, even though I had no particular project in mind. -- It turned out to bean Air-Dux no. 375-7433-PI,but any similar Low pass T match transmatch circult offers good harmonlc coil will do. I center tapped the coil and used it as the top attenuation. Finding two suitable roller inductors can be both of the "T." I was uncertain about the coupling effect of both difficult and expensive. Ham Rad~o/June1990 59 UNADILLA ANTENNA MANUFACTURING CO. W6SAI BOOKS W Box 421 5 BV~AndoverMA41BtO by HR Bill Orr, (500) 4757831 OurrSpm EST.(508) 4744M9 24HR FAX noted columnist WGSAI.

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60 Ham Radio/June 1990 Final verslon of tuner enclosed In shielded metal case offers better Author's breadboard version of tuner otters simple uncluttered con- confinement of harmonic energy. Note that the capacltor bodies struction and quick access to the traveling alllgator clips. Note that are RF hot and are mounted floating above ground. Cabinet Is roomy insulated knobs and shaft extensions should be used on high pawer enough to permit future installation of an Internal SWR meter. WJK models to protect the operator from RF burns. W7lJK photo. photo.

a triband cubical quad with an SWR of greater than 1:l. I adjusted all of these easily to a 1:l SWR. At my cabin in the woods I have a 400-foot wire, 60 feet high, fed on one end with open wire feeders (see Ham Radio Horizons, October 1979). 1 achieved a 1:l match on all bands, 10 TO XMTR TO ANT through 80, with this tuner. Photo B shows the finished product in an aluminum box with two tap selector switches. The space at the top of the box is reserved for a built-in SWR meter. You needn't use C I a box this big; I simply had this one on hand. Roller Inductor problem solvedl Conventional Air-Dux coll, wlth alllgator taps, Is used instead of cumbersome roller Inductom. The High power variable capacitors, salvaged from old broadcast receivers, allow Obviously, this coil isn't meant for a kilowatt, nor are the finite adjustment of the inductor settings. capacitors. The unit works well with an FT 101. If you run a kilowatt of power, and are only interested in the 10, 15, halves of the coil, but it worked fine. I used capacitors from and 20-meter bands, a ten-turn coil made out of 114-inch old radios; many of them are available in lots of bargain copper tubing will suffice. You could even use a hinged lid sheets. Mine are two gang, but I only use one half. I used box and some husky traveling clips to avoid large contact the breadboard in Photo A and traveling alligator clips in selector switches. If you do this, you'll need medium spaced place of a rotary switch to determine if the circuit would transmitting capacitors. really work. It did! A shielded box isn't absolutely necessary, I hope you'll try this tuner. I've found that it really does but it might help reduce Wl. If your primary goal is to match discriminate against harmonics. a random length wire while camping, you can just use the bread board. REFERENCES 1 Doug DeMaw. WFB, and Bob Shr1ner.wAQUZ0."Match~ng the bansrnftterlo the Load,"0% I used the tuner briefly on an 80-meter dipole which had February 1980 page 22 an SWR of 1.7:1 in the phone band, a 40-meter dipole, and 2 Bob Ba~rdWTCSD. 'Desgmng Irnpedancemmch~ngSystems' Ham Radn. July 1973 page 58

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Ham Radio/June 1990 61

Tom McMullen, WlSL ator size capable of handling true power ('just over 1000 watts), the extra 600 watts could do real damage. Elementarv Elec- Here's another way to determine the tronics - wrapping power factor of that circuit. The circuit has an inductive reactance of 18 ohms Up AC Theory and a resistance of 17 ohms in series. In my April and May columns I looked By using the information on vectors at inductances and capacitors and the from my earlier columns, and doing a way they affect alternating current. This 1, the ammeter shows 8 A flowing in bit of intuitive reasoning, you might month I'll show you what happens the circuit; the resistor is 17 ohms. guess that the vector of these values when you have both of them in a cir- Using Ohm's Law, P = I2R, 82 = 64 would come out close to 45 degrees. cuit, and discuss some unusual terms x 17 = 1088 watts. Note that you're (The vector is the hypotenuse of that apply when working with complex using watts here, not volt-amperes. The resistance plotted horizontally and the circuits. power dissipated in the resistor is real reactance plotted vertically. The Current, voltage, and power. You can feel it as heat when you resistance and reactance are only 1 touch the reststor. In circuits that don't phase revisited ohm different in value). With a vector have a physical resistor, there's still of 45 degrees, the impedance will be Remember that an inductance resistance present in wires in the approximately 1.414 times either the causes the voltage to lead the current inductance, transformer, electric motor, resistance or the inductive reactance. through a circuit, while a capacitor has or whatever equipment you're using. Therefore, impedance (Z) = 1.414 x the opposite effect. But how do you The power dissipated as heat will show 18 = 25.45 ohms. You can work this calculate power in a circuit if the cur- up as a warm (or overheated) inductor, out another way to see how close it rent isn't in phase with the voltage? motor, and so on. You can determine comes. The formula says that: The term power factor, abbreviated the power factor for this circuit. Appar- = d(~2 XL2) = pf (don't get this mixed up with ent power equals E x I, or 200 x 8, Z + picofarad, or pF) comes into play here. or 1600 VA. You previously determined a72 + 182) = Power factor is usually expressed as a that the true power in the circuit is 1088 ma9 324) = 24.758 ohms. number less than 1, like 0.6, 0.85, and watts, so 108811600 = 0.673, or 67.3 + so on. Some people use it as a per- percent. That's pretty close to our vector centage like 55 or 92 percent. More So why bother with volt-amperes 'Quesstimate" of 25.45. Round this off about that later. and power factor if you know the true to 25 ohms. With 200 volts applied to Power factor is determined by the power in the circuit? There are several the circuit, current (I) = EIZ, or 8 A. ratio of true power to apparent power. reasons to be aware of VA and pf. It's This gives an apparent power of 200 Figure 1 shows a circuit with an induc- very important to provide the correct x 8, or 1600 VA, confirming your first tor, a resistor, and meters to measure size of wire and components in acircuit. calculation. applied voltage and the current that's Also, you don't want to overload the cir- You can find the true power with this flowing. Apparent power is determined cuit's AC source (generator, amplifier, information by obtaining the power fac- by multiplying the voltage by the cur- etc.). If, in the preceding example, you tor. A different way to find the pf is to rent, just as you do in a DC circuit. had planned for a wire size and gener- use the ratio of the resistance to the However, in this situation the result is expressed in volt-amperes, or VA, instead of watts. This difference is important, as you'll see in a moment. True power, as you might suspect, is what's being dissipated in the resistive part of the circuit. Because the inductor stores energy in its magnetic field during one part of an AC cycle and releases it when the cycle reverses polarity, it doesn't dissi- pate any energy (unless the magnetic field intercepts something nearby). This means you can ignorethe inductor as far as power consumed is con- I J cerned. You work only with the A simple AC circuit with Inductance and resistance in series. The impedance, 2, is dib resistance. In the case shown in Figure cussed in the text. Ham Radio/June 1990 63 impedance: pf = RIZ, or 17/25 = 0.68. Now find the true power by multiplying. VA x pf 1 I equals the true power in watts, or 1600 x 0.68 = 1088 watts - which is what the resistor appears to be dissipating. Using Ohm's law again, I = PIE = HIGH z AT RESONANCE RESONANCE 10881200 = 5.44 A appear to flow in the resistor. Where's the extra current going? It's building up a magnetic field in the Xc= X' inductor in one half cycle, and return- (0) (b) ing to the circuit during the other half cycle' It'' lost9but does flow in the A resonant circuit results when the capacitive reactance and inductive reactance are equal wiring and must be taken into account. but opposlte. A parallel circuit is shown at (a); a series circuit at (b). Inductance and capacitance combined I = EIZ = 200118 = 11.1 A,and when you connect them together, as if It should be apparent that you can apparent power = E x I ,= 200 x in Figure 3? get the power factor back to near 100 11.1 = 2,220 VA, and A simple explanation is that each percent, many of the problems will dis- true power = 12 x R = 123.2 X 17 rnakes up for the other's actions, or appear. Everything I've just discussed = 2094 watts; they balance each other out. Another in relation to inductive reactance therefore, explanation is that they form a resonant applies to capacitive reactance. So if power factor = 209412220 = 0.94, circuit. The requirement for resonance capacitors cause the current to lead or about 94 percent. is that "the capacitive reactance and the voltage, why not put a capacitor in That's a significant improvement. the inductive reactance must be equal the circuit to bring things back to nor- Note that the current flow has increased and opposite at the frequency of mal? That's exactly what's done in because the phase difference between interest." This works whether they are many cases where a severe power fac- voltage and current is smaller. connected in parallel (Figure 3a) or in tor problem exists. The resistance is now the more sig- !series (Figure 3b). This tuned circuit I've placed a capacitor in series with nificant part of the circuit. By selecting concept is basic to operation of radio the inductance in Figure 2. The capac- the right value of capacitance, you can equipment. It lets you separate one itor has a reactance of 12 ohms. obtain a pf that's very close to 100 per- signal from another, reject a wide spec- (Remembering the discussion of the 'j" cent. As usual, circuit losses will pre- trum of signals while accepting others, operator, you can say the reactance is vent perfection. and generate and amplify your trans- -j12.) The impedance formula now That's heavy stuff and while not mitted signal while rejecting harmonic becomes: directly applicable to most of what you and spurious energy. The basic pur- z = J(R~+ XL - SC)~, or do in Amateur Radio, it's part of AC the- pose of the circuit you need dictates ory - a basic foundation for all elec- which configuration you choose. -\/(172+ 18 - 12)2), or tronics. If you want a circuit that will reduce (289 + 36), = the signals outside a band while allow- Resonant circuits ing those inside to pass, you want a Z = 18.02 ohms. You've seen how inductances delay-. parallel circuit (Figure 3a). This is Now, put Ohm's law to work on some current flow and capacitances because the parallel circuit appears as other numbers: advance current flow. What happens a high impedance to any signals at its resonant frequency. But off-resonance srgnals see a low resistance and are shunted to ground. By making either the inductance or capacitance variable, you can ''tune" the circuit to a desired frequency, as is done in the front end of a receiver or in the output stage of a transmitter. If you want to "trap" a frequency and keep it from passing, you can connect an L and C in series (see Figure 3b). A series resonant circuit has a very low impedance at its resonant frequency, and signals at this frequency will be I I shunted to ground while others will not. The circuit of Figure 1 with a capacitor added in series. This changes the power factor Most of the bandpass and band- and the current flowing, as shown In the text. reject filters used in modern Amateur

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Stephen M. Hall, WM6Fj 664 Bristol Avenue, Simi Valley; California 93065

he use of diversity reception in radio communica- 930S, Kantronics KT-120, and Collins 51J-3 (R-388). 1 tested tion isn't new to either commercial or Amateur sta- various modes, among them were AMTOR, RTTY, and Ttions. It's been used successfullv since the 1940s to packet. improve RTTY signal copy. In the past,*this technique nor- I observed deep fades on both horizontal and vertical mally involved switching between two or more receivers polarization, but the fade wasn't normally seen on oppos- based on strength of the received signals. In the reception ing polarities at the same time. At times the fading was as of high frequency packet radio, signal strength alone is great as 40 dB on 14 MHz; it would alternate or cycle usually insufficient to judge the quality or completeness of between polarizations at rates of between approximately a received packet of digital data. 112 to 4 seconds per cycle. I've conducted some experiments to evaluate the improvement in reception on HF packet radio when multi- My observations of the two video terminals on RlTand ple antenna polarity diversity is used. Here are the results AMTOR modes revealed reception errors which alternated of those tests. between displays. The incidence of simultaneous error Initially, I assembled two parallel HF packet stations to reception was less frequent. It appeared that a large measure and compare the performance of different improvement in copy would be achieved if the two chan- modems and terminal node controllers (TNCs) available to nels' signals could be merged into a single display. On Amateur packeteers. I extended these tests to include packet, I saw frames from the same station alternating regu- enhancements in reception using two antennas and two larly between terminals. I was seeing unique packets - receivers, both tuned to the same frequency. The antennas those copied on one TNC but not the other - on a single I used in the test were a horizontally polarized four-element screen more frequently than I was seeing them on both ter- beam at 60 feet and a 1-wavelength Zepp, center fed with minals' screens simultaneously. kW twin lead and a balanced tuner. The Zepp was sup- The use of an additional antenna which would take ported by the common tower in a sloper configuration; advantage of a second polarnty appeared to be a technique polarization was primarily vertical. During my early tests, worthy of greater investigation. After several hours of obser- I used two Kantronics KAMs with individual video displays. vation, I could see the obvious benefits of this technique. I placed them side by side, so I could observe the perfor- Fortunately, a program was developed which would let me mance of each parallel system in real time. The receivers measure the improvements using my computer. I used in various parts of the tests included a Kenwood TS- This terminal program lets me gather statistics using an

Ham Radio/June 1990 67 IBM-AT computer: I can interface two communication ports or a single higher gain antenna to obtain improvements of on the computer to two terminal node controllers. The sys- this magnitude. Improving existing nondiversity perfor- tem can then count the total number of packets received mance by using more power would only load the frequency by each KAM and the number of packets received uniquely further and slow the passage of traffrc on the network. An by each one. I'm able to measure the improvement provided inherent advantage in using diversity is that rt doesnY require by an addition of a second channel or system. that both stations partic~pate.A single user may add the I ran tests to measure systematic errors in the software, capabil~tyand enjoythe results independentof other stations. like the failure of the computer to properly count packets Other techniques that have been proposed to improve HF common to both channels and unique to each. No errors packet, like changes in baud rate, frequency shift, or modu- were observed. Then I ran further systematic tests to estab- lation technique, would require substantial changes to all lish that all variations between channels would be due to Amateur packet stations to maintain compatibility within the antenna performance alone. I took off-the-air audio from a network. This would be difficult to achieve as there are large angle receiver and fed it to both KAMs. I observed diver- numbers of stations using the current standards. sity between the KAMs alone; one unit consistently received Because there's more to communicating on packet than 1 percent more packets than the other. I didn't find this sur- data reception, the TNC must acknowledge each received prising. What was surprising was that when two terminal information frame while connected when this technique is node controllers were used in parallel, 14 percent more used in other than monitor mode. If two TNCs are used, unique packets were received - even though the TNCs they must work in concert to maintain a proper connection were demodulating the same audio. I was observing TNC with another station. This would require new software within diversity. These observations were consistent with those I the two interconnected TNCs, or a dual port TNC to moni- had made using the two video terminals without the aid of tor two incoming signals from two independent receiver1 the computer. The addition of a second TNC contributed antenna systems. Orle TNC port would act as a primary; 434 additional packets out of an average of 3064 received the second TNC wo~rldcontribute packets not received on by the two units. the primary channel. The TNC's microprocessor would At this point. I connected the second antenna to allow compare data received on each channel and send acknow- polarity diversity reception. I ran tests at different times over ledgments for correct frames received on either channel. several days on 14.109 MHz on the SKIP-NET packet net- Other statistics showed that, based on total packets work. I chose SKIP-NET because most of the stations in received and independent of the use of diversity, the gain this net are generally in the pattern of both antennas. I antenna received 27 percent more packets than the Zepp. pointed the beam northeast from my southern California receiving location. The Zepp antenna slopes in a similar The experimental installation direction, but the pattern is difficult to predict because of I used the following hardware to add diversity to my station. rts wavelength. When I included the second channel, I added a second The station received an average of 3344 packets using receiver. I already owned a TS-930S, which has proved to diversity; 2935 were received on the vertically polarized be a good performer on HF packet. Kantronics provided antenna and 3753 were received by the channel using the a monoband KT120 for my tests, and I also tested a Collins horizontally polarized beam. I believe that the difference in 51J-3 purchased at the Dayton Hamvention@ for $100. Both performance between the two antennas was due to antenna proved quite suitable for packet reception. I used my exist- gain rather than polarization. I used both receivers and ing 66-foot Zepp without modification with excellent results. KAMs in a series of configurations to rule out the possibility With suitable coritroller software, you need no other that the differences were due to anything other than those equipment. Only one video display is normally required for contributed by the antennas. On the average, only 1305 diversity packet or AMTOR, though I used two in the packets of 3344 average total packets were received on experimental configuration. Even when I grouped the lesser both channels - an incidence level of 39 percent. Use of antenna, TNC, and receiver as the second channel, their the second channel added 61 percent more unique contribution accounted for a 56-percent improvement when packets. This seems to indicate that if the majority of net compared with the primary beam antenna, TNC, and bet- users were to incorporate this improvement, network load- ter receiver. ing would be significantly improved due to the elimination of many retries. Conclusions My observations on other digital modes appeared to Because I anticipated only modest gains using this tech- demonstrate similar improvements, but I was able to gather nlque, the tremendous improvement in reception which statistics using fairly simple computer techniques only with resulted was a surprise. I hope that suitable software for packet. Because data with errors won't be presented to the the currently avarlable TNCs will be developed by the output of the TNC, all data counted by the computer is packet community or the manufacturers of multimode con- known to be good. This isn't the case with monitored trollers which will allow diversity to be incorporated in HF AMTOR or RTTY. Other techniques would have to be used packet stations. I have spoken with TNC manufacturers who with these modes to use a computer to gather statistics. w~shto add this capilbility to their dual port designs. In some If new terminal unit software were written for AMTOR which cases, this will be a:; simple as making firmware upgrades would allow users to take advantage of diversity, it's possi- available on EPROM. ble that even larger gains could be realized than those on I wish to thank Phil Anderson, W@XI,and Karl Medcalf, packet, as individual AMTOR character groups could be WK5M, of Kantronics for their generous support of both time compared or combined. and equipment, which allowed me to pursue these experi- It would be impractical to use additional transmitter power ments in digital diversity.

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GREENVILLE. NH 03048 (603) 878-1441 FAX (603) 878-1951 IPlease enclose $3.75 shipping & handl~ng ~UTERPROGRAMS 1 bv John Devoldere. ON4UN I ,"st aboul every lntrrest or need IS cowred-homantennadeslgn and optimizahonlo general operat ng programs Anlenna programs tncluae shunl and serles ~nputL network deslqn. Ieedllne translormer, sh~nlnpmfk design. SWR calculal~on.plus 11 more1General ham programs Include sunr~se~s~ns~t.great clrcle dlsfances, qfayl,ne, verttcal anlenna deSlgn orooram, sllnrlse ca,endar p LS~morel The bps1 va be In computer softwareava~labletoday < 1986 L UN Apple lldllc $39.95 er. CUN.MS (MS-00s) U995 8s. c UN.CPMll(ayprn $39 95 ea. L UN-C 128 (COMMODORE) $39 95 sa. CUN-MAC (MACINTOSH) 509 95 LOW BAND DX'ING by John Devoldem, ON4UN Now Ava~lablelThe new 2ndedltlonof thedefin~hvebookonLow BandDX'ing Based upon years of practical on the-a~rexpenence, learn the secretsof how ON4UN has been so successful on the low bands Extens~vecoverage IS glven to transmlt and recelve antennas w~thclear conctse explanations and plenty of ~llustrat~ons-d~poles~nverted V s, slopers phased arrays and Beverages-they reall In this book Alsocovered propagation transm~tlersreceivers operating, sottware and an extenslve Low Band b~b- l~ographyGo~ng to be a best seller1 Get yours today 1987 2nd Editton 200 pages IW SdmandS995 ON4UN PRACTICAL YAGl DESIGN ws-ws) by John Dwoldem, ON4UN Th~scomorehens~ve Yaa~ desian Droaram is based uoon tested antennas, not theo- ret~calun'proven models ~onia~nslb~d~tferenl HF antennas, destgned, tested and I oot,m~zedbr ON4UN Also conta~nsa number of classic deslans bv noted antenna I experts W~W.W6SAIand others Includes mechan~caldes~qn6feleinentsandof the rotatlng mast You can also add to the database your own des~gnsFully deta~led "Read me' file 1s deslgned to help the user qet maxlmum results from the program (L 1989 72 Ham Radro/June 1990 I r ION-YAGI (MS-DOS) $59.95 1 Garth Stonehocke~KbRYW turbances from the 5th to 8th due to solar flares, and from the 10th to 14th and the 20th to 24th as a result of SUMMER SHORT decreasing solar flux and coronal holes. As the month passes, the build- SKIP SIGNALS up of thunderstorm noise will be Each summer during June, July, and increasingly evident towards the even- August, plus a week or so into May ing of each day. Es propagating and September, short skip DX is modes will also build up during the enhanced. Short skip is propagation month. The moon will be full on June from the E region of the ionosphere, 8th and at perigee (its closest about 100 km above the earth. The formation. Es also varies with the num- approach) on June 21st. Summer sols- geometry of propagation from a trans- ber of sunspots on the equatorward tice occurs on the 21st at 1533 UTC. mitter to a receiver, with a reflection edge of the auroral zone, where parti- The Aquarid meteor shower starts height of 100 km tangent at the earth cles enter the E region from the solar around the 18th, peaks about the 28th, at each end (zero takeoff angle), wind. The solar wind increases when and lasts until August 7th. The maxi- defines the maximum distance for a the sun's spots flare (brighten). As a mum radio echo rate will be 34 per hop at 2000 km (1200 miles). This result, many clouds of Es which help hour. enhancement results as the ionization with VHF auroral propagation develop Band-by-band summary produced near that height is moved in this region. horizontally (bunched together) by the Now look at short skip Es signals. Six meters will provide occasional electrojet current from the geomag- For a given distance, Es signal strength openings to South Africa and South netic electric field into high density ion is an average of 12 dB greater than America around noontime via multihop clouds. The clouds average in area that of regular E signals as a result of short skip Es propagation. about 40 by 500 miles wide and 6 the mirrored reflection. The signal Ten meters will have long skip con- miles thick. strength is usually compared to the ditions for many hours in the afternoon These thin ion clouds are embedded free space loss or signal decrease with during the peak times of the 27-day in the regular E layer created during distance at the frequency of transmis- solar cyc:le. Otherwise, look to sporadic the daylight hours by the sun's ultravio- sion. A formula for relating this in E short skip and multihop openings let light. The E layer supports a maxi- decibels (dB) is: around local noon for DX on this band. mum signal frequency of 3.8 MHz at (Evening transequatorial openings local noon during sunspot maximums. usually don? occur in the summertime.) A signal can be increased up to 19 Twelve, 15, and 17 meters, almost MHz and still be reflected if it hits a where d is distance in miles, f is always open to some southern part of cloud because of the higher ion den- frequency in MHz, and 98.88 is a the world, will be the main daytime DX sity and this reflection. Yes, reflection. constant set by arelationshiptothe refer- bands. Operate on 12 first; then move The regular E is gradually bent down, ence antenna used in the measure- down to 15. DX is considered 5000 to or refracted, while the sharper edge of ments, the units used for d and f, and 7000 miles on these bands. You may the thin cloud causes a more mirror- the normalized path attenuation in the find some long one hop transe- like reflection downward. The location locations where the measurements quatorial propagation paths early in of the ion clouds is similar to that of were made. Therefore, the formula can the month. scattered weather clouds in the sky - be used at any location, one hop dis- Twenty, 30, and 40 meters will sup- hence the name sporadic E (Es). tance, or any frequency band. Just port DX propagation from most areas Because the E layer increases with the subtract the dB for Lb from the free of the world during the daytime and number of sunspots, the embedded space loss of this formula: into the evening hours most days. DX Es clouds' ion density also increases. on these bands may be either long This is the only sunspot effect on mid- skip to 2500 miles or short skip Es to latitude Es. It is almost constant, and 1250 miles per hop. There are many occurs every summer. The units in Equation 2 are the same good hours of DXing ahead during the There are areas of the world where as those in Equation 1. These formulas long summer days. sunspots affect Es propagation for the E region can be used to obtain Thirty, 40, 80, and 160 are all good because of increased geomagnetic the signal loss or, inversely, the signal for nighttime DX. Although the back- disturbances. Larger numbers of strength's lowest value at a probability ground thunderstorm noise is becom- higher intensity Es clouds develop of near 10 percent. ing noticeable, these bands are still where the geomagnetic and geo- quiet enough to provide good DX graphic equators are widely spaced in Last minute forecast working conditions. Sporadic E propa- latitude - near Southeast Asia, South The higher frequency bands will be gation may contribute to enhanced America, and Africa. The greater elec- best the first two weeks of June. The conditions at local sunset and will trojet current that develops in these lower bands become strongest during occur rrlore often during the next three areas leads to this increased Es cloud the third and fourth weeks. Expect dis- months.

Ham Radio/June 1990 73 D

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74 Ham Radio/June 7990 IREETINGS & GOOD NEWS 1 == Gss=%F bROM THE HAMS AT

ELECTRONICS A Spring-Summer 1990 KIT NEWS KEYER mSlDRONE! "code practice oscillatd' when the CW-7 ly-formed CW and will also key your rig?

METER CW FUN!

and nm?s with 10.107 Mhz. crystal. , 124.95 U QRP-30 VXO Transmitter Kit, 129.95

details spedal support and . Please specif-+ number d

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FU Receiver Kit "If itP buih by Rurrwy, it's RelLblc." - CF R-7 12.95 Case and Knob Klt for FU Receiver Kits 51-7 14.95 Broadband Preanp Kit (20 dh. 100 KHz-ICHz.1 CT-70 139.95 2OHz-55Wz Frequary Counter - - PA-I0 17.95 Hnm 1-0-kter Preamp Kit - Cl-90 169.95 10Hz-600Utlz Frcqusncy Counter - - C1-50 189.95 5Hz-600UIir Frequency Counter - PR-20 17.95 220 MI Preanp Kit CT-125 189.95 IflHz-I.25GHz frequency Counter - PR-40 17.95 440 UHz Preamp Klt - - PA-I0 69.95 Two-Peter Power Roostmr (wired d. tasted) s169.95 ZL?%-~ - PA-20 69.95 220 UHz. Power Booster (wlred 4 tqated) - PA-44 79.95 440 hz. Pow~rBooater (late Spring 1990) OW-1 59.95 0.1 PI% OGen Tlme Base - PA-1 27.95 2-bier Pow~rAnpl~fler Klt - TR-1 6.95 RF-Smsed T-R Relay Klt El-l 11.95 External T~meBase Klt - - BP-4 8.95 NiCad Pack for all Counters P-64 49.95 Peck~tRad~o Kit for Camudore 64/128 W or VIC - JU-7 12.95 RF Modulator/6-Meter ATV Kit - RA-I 14.95 Ham/SM Recervsr Adapter Klt (For CT-50 only) - - PS-l 89.95 1.5 Ghz. 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FU-3 16.95 Wlreleas FU flln~mlkeKit with case, battery SR-l 24.95 4-11 bhz. AH Shortwave Recelver Kit - FU-4 12.95 Hlqh-Power FU Mlke Klt I - CSR-1 12.95 Shortwave Hecelvrr Case Klt - PR-1 14.95 Telephone Transmlttcr Kit - AR-I 24.95 An 108-138 -2. Alrcraft Band Receiver Kit - FR-I 14.95 fU Rccelver Kit (tunes appror. 70-130 Wz.) - CAR-1 12-95 Alrcraft Recc~verCase Kit - BN-9 5.95 "Super Sleuth" hltl-Purpose 2-watt LM38O Kit - SC-l 24.95 Automob~leAU Redlo Shortwave Converter Klt - M-l 8.95 Color Organ Kit - CSC-1 12.95 Caae Kit for SC-l m-1 4.95 "Pad Blaotwr" Klt (ale0 can be LOU0 code oaclllator') - - LED Bllnky KI~ (flashea 2 Jumbo LEO'S) CLG-1 2.95 Quallty Cigarette Lighter Power Cord -- - BL-l 3.95 - - W1-l 6.95 Wllsper Llght Klt - 5n-3 3.95 Slren Klt - LIT-5 5.95 Universal 555 Timer-Oaclllator Klt (bny applicattm) HAM HF-BANDS KlTS & STAWN ACCESSORIES VS-l 6.95 Uolce Activated 5*1tch klt CU-7 24.95 CW)S CW Keyer with Built-ln Sidetone - KJ-3 16.95 U~crowave(1.3 Ghz.) Intrueion Alann Klt - - Touch Lltch Kit (makes 2 conplete touch srltcheel) - CA-CY 12.95 Case and knob klt fol CU-7 Keyer - 15-1 6.95 H9-20 24.95 Amateur 20 Mter Receiver Klt W-. rseeivera am - 10-1 5.95 Tone Encodcr-Dccoder Kit - - LB-5 9.95 Infra-Red Beam Comnunlcationa Recelver Kit - MU-JO 24.95 hateur 30 Ucter Recelver Klt IE602~d~rsct- 10-6 8.95 Infra-Red Ream Comnunlcatlons Transmlttcr Kit - MY-40 24.95 Amateur 40 Ueter Rece~verKlt cmvemion for 558, - - HR-80 24.95 Amateur 80 Fleter Recclver Klt N, RllY recsptlon. - Hd-160 24.95 Amateur 160 Meter Recelver Kit - CdR-I 12.95 Case and Knob Klt for HA-serlea Recelver Klts AND - OAP-20 29.95 UXO 20 Ucter Transm~tterKlt wlth 14.060 crystal "A" . .WHILE YOU'RE CRTlffi YOUR ORDER TOCETHER, - ONP-30 29.95 VXO >O Uetrr Transmlttcr Klt w~th10.107 crystal "A" rrmcnbattutvovbcalh.mdubarcprvtcrlaobHm - T<-30 39.95 6-watt 10.1-10.120 Mz. 2-cryatal VXO Transm~tter anunmurrwnbc~famembcnrnth.nE-ZRy~n... - QRP-40 29.95 UXO 40 Fleter Transm~tterKlt wlth 7.010 crystal "A" - QRP-80 29.95 UXO 80 Wter Transmlttcr Klt w~th3.560 crystal "A" 2795.00 - TIJRP-I 12.95 Case and Knob Klt for Tranamittcra CW3 Rdcssional Camnunicatims Service Monitor - A,!-7 25.00 Artlve Antenna Klt for W ad UHF COM-7 3495.00 Spect~mAnalyrer - CA-AA 12.95 Case and Knob Klt for AA7 Actlve Antenna RSClO 2495.m Synthesized Signal Gemrator

151 FOUR ACRES of flat Arizona land In the beautiful San Pedro HAMLOG" COMPUTER PROGRAM. Full features. 18 mod- Valley about ten miles from Sierra Vista via excellent road. Lles. Autologs. 7-band WASIDXCC Apple, IBM. CPIM. Water on property with power and telephone at boundary. Zon- KAYPRO. Tandy, C128 $24 95. HR-KAIAWH.POB 2015. Pea- ing provides for antenna towers. Would make ideal antenna farm lor retirement. $20,000. Write KlYSE, Box 1538, Bisbee. - AZ 85603 for details. IMRA InternationalMlssion Radio Association helps mission- aries. Equipment loaned. Weekday net. 14.280 MHz. 1.3 PM WANTED FOR MUSEUM: Early mlcrocomputers, SWTPC Eastern. Nine hundred Amateurs in 40 countries. Rev. 6800. Sphere. Altair MITTS 6800 and other early micros. Also Thomas Sable, S.J.. University of Scranton. Scranton, PA early mirocomputer magazines. David Larsen, KK4WW. 18510. Blacksburg Group. PO Box 1. Blacksburg. VA 24063-0001. (703) 231-64781763-3311. WANTED: Henry VBC 3000. Dick (716) 386-4092. WANTED: Ham equrpment and other property Tne Radlo INTERESTED IN PUBLIC SERVICE? Joln our Local Radlo Club ol Junlor Hlgh School 22 NYC, Inc 1s a nonprol~torgan#- limergency iusoc~atedCommun~cat~ons Jam In Pennsyl- zatlon oranted 5011C113) status bv the IRS, InCOrOOrated wllh vanla call 17171 936-6943 or wrlte REACT. 1160 Old Tra~lRd. the goaj of usrng ihe'theme of am ~adioto.further and Etters. PA'17a9. enhance the education of young people nationwide. Your properly donation or financial support would be greatly RUBBER STAMPS: 3 llnes $500 PPD Sen0 check or MO to appreciated and acknowledged with a receipt for our tax G L Plerce. 5521 B~rkdaleWav. San Dlego. CA 92117 SASE deductible contribution. Meet WB2JKJ and the "22Erew's at brings lnformatlon. Knoxville. TN HamfestonJune2. Joe Fairclou hwill bethefea- - - lured speaker telling the incredible story of tae first 10 years ELECTRON TUBES: Recenlng. transmdlng, microwave all of educationthru communication at the core of the Big Apple. t pes available Lar e stock Next day dellvery most cases Write us at: PO Box 1052. New York, NY 10002. Round the ~AILYELECTRONI~S. PO Box 5029. ~om~tin.CA 90224 clock hotline: VOICE (516) 674-4072. FAX (516) 674-9600. (213) 774 1255 ATTENTION: EARN MONEY READING BOOKS1 FLEA MARKET $32,00O/vear income Dotential. Details 1-602-838-8885.Ext

RECONDITIONED TEST EQUIPMENT $1.25 for catalog. Walter, 2697 Nickel. San Pablo. CA 94806. RATES Noncommercialads 10C per word: commercial ads 60@per word both payable in odvance. No cash discounts or agency com- PACKS" ICOM: BP5 $43.95, BP~(Base Charge Only) 39.95, missions allowed. YAESU. FNBB 819.95. FNB11IFNB14 $4495. SANTEC. Activities "Places to go I' 142/1200$2195 TELEPHONEIPAGERICOMPUTERICOM- - . . HAMFESTS Sponsored by non-profit or- MERCIAL PACKS-Free catalog Add $300 sn~pp~nglorder ganizations receive one free Flea Market ad PA +6% VIWMC add $2 00 CUNARD. AD 6 BOX104 Bed- SPECIAL REQUEST m ALL AMATEUR RADIO PUBLICITY ford. PA 15522. (814) 623-moo. COORDINATORS: PLEASE INDICATE IN YOUR (subject to our editing) on a space available - ANNOUNCEMENTS WHETHER OR NOT YOUR HAMFEST basis only. Repeat insertions of hamfest ads VIBRWLEX COLLECTOR'S GUIDE. WlIMO's new illustrated LOCATION. CLASSES. EXAMS. MEETINGS. FLEA MAR. pay the non-commercial rate. reference. Key Histories, identification guide, patents, more. KETS. ETC, ARE WHEELCHAIR ACCESSIBLE. THIS 67 pages. Only $14.95 plus $2.00s/h. Free info. Artifax Books, INFORMATION WOULD BE GREATLY APPRECIATED BY COPY No special layout or arrangements Box 88-H. Maynard. MA 01754. OUR BROTHERISISTER HAMS WITH LIMITED PHYSICAL available. Material should be typewritten or ABILITY. clearly printed (not all capitals) and must in- KITS: OPR CW TRANSMITTER. 1 wan w~thcrystal 60m or 4Om $1900 each Code oractfceoscrllator, $900 ($14 00 wrth JUNE 1-2: GEORGIA: 1990 ARRL Georgia State Convention clude full name and address. We reserve the key) Both great for Novice classes SASE for ~nfo.WDBOYG and SE Packet Conference, Herita e House Motel & Conven- right to reject unsuitable copy. Ham Rodlo can- (301) 586-ZITI. SR1. Box 2C. St. Leonard. MD 20685. tion Center, Albany. Admission $3.%ree parking. For informa- -. tlon Albany ARC. POB 1205, Albany, GA 31702. (912) 883-7910, not check each advertcser and thus cannot be ATTENTION-HIRING1 Government obs your area. $17,840- M-F, 9-5. held responsible for claims made. Liability for $69.485. Call 1-602-838-8885. Ext il157?2. correctness of material lim~tedto corrected ad JUNE 2: ONTARIO: Central Ontario Amateur Radio Flea Mar- TEN-TEC, New boxed latest 1990 prOduCtlOn models. USA ket. Blngeman Park Kitchener Ontario. Canada. Contact Ra in next available issue. made 562 Omnl V, 585 Paragon Transceiver. T~tan425 15 Jennings, VE~CZE:61 0ttaw; Cres., Guelph. Ontario, NI~ DEADLINE 15th of second preceding KW and420 Hercules 1KW liriaar amplifiers, antenna tuners 2A8. Canada (519) 822-8342. month. models 238.253.254.239.240 drv dummv loads. 25108 sat- elllte statlon, moblle HF antennas, keyen, cabinets, filters and JUNE 2: KANSAS: The Pittsburg Repeater Or anization's SEND MATERIAL TO: Flea Market. Ham accessories VlSAlMC or check, for best oeal wrlWphone Blll annual Hamtest. Lincoln Center, 709 West 9th Jtreet. Pitts- Radio. Greenville. N. H. 03048. Step (704) 524-7519, Slep Electmn~csCompany, H~ghway441. burg. 8AM to3 PM. Admission $5.00 includes chicken dinner. Otto NC 26763 Contact Ken Johnston. 2402 Wall Avenue, Joplin. MO 64804. (417) 623-1895. 1990 IDAHO HAM DIRECTORY. Calls. counties. phone numbers. names. addresses. $10.00. Ken Hastinos. Box 434. JUNE 2-3: WASHINGTON: The A ple City ARC'S Hamfeast, Nampa. Idaho 83653. Rocky Reach Dam, Wenatchee. Registratron: Amateurs $5. Others $1. Under 12 free Free camplnQ and trailer soaces. WANTED: Rotary Inductor Johnson 226-1 4 or equivalent, 275 many area attractions. Mail registration 16 Bob Lathrop,'Treas- BEGINNER'S RADIO CLEARINGHOUSE. On a space avail- turns of 118 ' x 3/16' rectangular wlre edge wound 35" OD urer. 919 N. Woodward Drive. Wenatchee. WA 98861. able basls. we are golng to offer you, OUR SUBSCRIBER. Spaclng between turns Increases toward one end Old cata- -- free of charge, a chance to flnd a home for your used equip- log llstlng 22 5 mlcro H Calvln A Hoerneman. 704 Apple JUNE 3: NEW YORK: Hall of Sclence ARC'S Electronic Ham. men1 with anew Ham. Please send us a short description Drlve. Mechanlcsburg. PA 17055 (717). . 766-3465 lest and Computertest Hall of Scrence Parktn Lot off 47th of what you want to sell along with price, name, address and avenue and 111th streit. Flushlng Meadow pax. Queens. 9 DhOne number. Please limit your ad to 20 words or less. FOR SALE: Teletype Model 43 with books and one box of AM to 3 PM. Donation Buyers $3. Sellers $%pace For infor. paper $100. New Wilson SY33 Tribander antenna and 33-6 mallon call Steve Greenbeaum WB2KDG 718) 898-5599or SMALL DUAL CONVERSION solid state FM crystal controlled MK 40-meter modification kit. $295. YOU SHIP. R. Davis, Phll Kubert, N2HYE (213) 77i-h648 EVEN(NGS ONLY. receiver on 462.875 or 441.475 MHz. Has 10.7 MHz and 455 W9KK. Colfax. IN 46035. (317) 324-2442. &solid state lffilters. Comes complete with re ulated power -- JUNE 3: CONNECTICUT: The Newington ARCS 7th annual sllonlv and XR-Y211 FSK demodulator. Wig make oood "SOFTSTART" Protect our valuable tubes and power sup- Ham Radio and Computer Flea Market, Newington HS. Rt K&Te'm Giver: Sihematic included. Can also be cokvirted ply d~odeslron; DANG~YROUS Inrush surge currents Can 173, Willard Avenue. 9 AM to 2 PM. Admission $3. For infor- to other freq. Several on hand. $24.95 each plus $3.50 slh. ratrofltted Into most am llflers Completely assembled Ama- matron SASE to NARL Hamfest. PO box 165, Pleasant Vel- Buddy L. Holmes. 117 Halsteed Road. Ocean Springs. MS teur net for 'SOFTSTART..1s $4995 pl~ls$500 shlpplng In ley. CT 06083. (203) 523-0453. 39564. Phone (801). . 875-5211 the 48 states OMEGA ELECTRONICS. 4209 Llve Oak Road. Ralelah. NC 27604 (919). . 231-7373 JUNES MICHIGAN: The Independent Re ater Assoc~et~on's FOR SALE: Kenwood remote VFO model VFO-120. Mint with -- annual Hamfestna~,44th Street Armory. Gron Center 8 AM manual. $75.00 Fred Weigel, WD4BBZ, 2249 Evangelina, Del- FREE LIST of low cost har? equipment. Write to Jim Braddy, to 4 PM Mmlss~on$3/advance, $Moor For ~nlormatlonwrlte tone. FL 32725. (904) 789-3869. WA4DSO. 3037 Audrev. Dr~ve.. Gastonia. NC 28054. l R A 562-92nd Street SW, Byron. Center. MI 49315 -. -- FOR SALE: 25108 mode B satellite transvener. $400.00 000. WANTED: BUY L SELL. All types of Electron Tubes. Call toll JUNE 9: MICHIGAN: CMARA's 16th annual Hemfest, Midland NIEHT, Jeanne. VT (802) 229-4035. Will ship. free 1-800-421-9397 or 1-612-429-9397. C & N Electron~cs, Community Center, Midland. 8 AM to 1 PM. Admission $3. Harold Bramstedt. 6104 Egg Lake Road. Hugo. MN 55038. For inlormatron SASE to CMARA Hamfest, PO Box 67, Mid- HAM CALL HATS: Qualit Baseball caps attractively printed -- land. MI 48840. (517). . 631-9228 eveninas and weekends. with call and name, only J6.50. While front, mesh back. Red. CHASSIS AND CABINET KITS. SASE. K3IWK. 5220 Har- -- green, royal or navy. VisalMC accepted. Include name, num- mony Grove Rd, Dover. PA 17315. JUNE 9: NORTH CAROLINA: The Forsylh ARC'S 3rd annual ber, expiration date, signature and telephone. No COD. Send Hamfest. Computer and Electronics Falr, Benton Convention to: Edmonds Screen Printing, 2555 Greenwood Road, Inde- ATTENTION: EASY WORK-Excellent Payl Assemble pro- Center, 301 West 5th Street, Winston-Salem. 9 AM to 3 PM. pendence. OR 97351. Please include $150 posta e and han- ducts at home. Details. 1-602-838-8885. Ext. W15752. Admission S4ladvance; 851door. Wheelchair accessible. For dling. Print or type color, call, name and OM or ?L. 9.50 less information SASE to Jim Rodgers, NIDRI, W-S Hamfest, PO for 2 or more to same address. Send SASE for informallon RTTY JOURNAL published 10 times er year tor those box 11361. Wrnston-Salem. NC 27116 or call (919) 760-2493. on club T-shirts. sweatshirts or iackels. KA7FJF. Earl. (503) interested in digital communications. Lead about RTTY. 9 AM to 10 PM. AMTOR, MS,O'S, PACKET, RTTY DX and Contesting. Plus - techn~calarticles concernln the dl ~talmodes. $12.50 per JUNE 10: ILLINOIS: The Six Meter club of Chicago will hold COMMODORE-128 PROGRAM Amateur Satellite trackrng year (foreign higher). RTTY QOURNL, 9085 La Casita Ave, its 33rd annual Hamfest, 91sl and Wolf Road, Willow Springs. program uses Keperllan data sup lled by NASA tree Tracks Fountain Valley. CA 92708. southwest of Chicago. Registration $3/advance; $41 ate up to 8 satelllt~ss~multaneously Frogram supports rlntlng -- Gates open 6 AM. Advance tickets from Mike Corben. K~!Nz; schedules, modes, end predlct~onsfor Satellites sAT~AK~~~CUSTOM MADE EMBROIDERED PATCHES. Your design, any 608 South Fenton Avenue, Romeoville. IL 60441 or any club VI I $2650 Includes sh~pplngOther lnformatlon on thls or shape and colors. Free oraerin information, price llst end member. other rograms tor the C128 requlres a buslness slze SASE random sample. HEIN. 79602 danitou Trail, Glen Arbor, MI Reid grlstor. WA4UPD. PO =ox 0773,Dept HR. Melbourne. 49836-9711. Flor~da32936.m AVANTEK ATF10135, $12.00, MMIC's, PC. board, SASE: WANTED: 8873 Tube end Socket. SK20 heat link. G2DFiT WAIIAC. 7l48 Montague St. Ph~ladelphia,PA 19135.

76 Ham Radio/June 1990 THE MOST POWERFUL HANDHELD LCR METER wl DISSIPATION FACTOR ANYWHERE!

BENCH-UNIT PERFORMANCE ...AT 20% OF THE PRICE FEATURES: Drop.Proof. Heavy Duty. Inductance: 200uH to 200H. Capac~tance:200pf to 20mf. Resstance: 2 to 20M ohms. (rnax. resolution. 1 m~ll~ohm). Dissioat~onFactor Measurement (D=: 110). 120Hz & lKHz Tesl Freouencles. SMD or chl~tme component lest p robes available.

APPLlCATll Foreign Subscription Agents Ouallty Conrrol UI rransformers (opera, shorts) for Ham Radio Magaz~ne F~nd~ngopens and shoris of lransrnc,-,".,:ctnn I~noc,,,,"" Capac~tance& resistance measilrerlllerl for Ham Rad~oFrance SM Eleclron~c SMD or ch~plvpe components. 20 b~sAve des Clar~ons Precison measurement of m~ll~ohrn F 89000 Auxerre France appl~cat~ons. Ham Rad~oCanada ' Phase Detection, Mutllal lnduclanca & Rallo of CARF (on microfiche) Turns for transformers P 0 Box 356 Ktngslon. ON Call Directory - by callsign ...... $10 Now ARI gives lhe ultimate ~n Handheld LCR Canada K7L OW2 Name lndex - by last name ...... $10 Meters. For delalls, call 1800)654.9ARA Prtces In CanadIan funds Geographic lndex - by statelcity ...... $10 1 yr $38 00. 2 yrs $67 00 3 yrs $90 00 All three - $25 $3 shipping per order Ham Radio Japan Kalsum~Eleclronlc Co . Lld BUCKMASTER PUBLISHING 27 5 lkegaml Route Box 56 4 Chome Ota Ku 3. Tokyo 146 Japan Mineral, Virginia 231 17 Telephone (03) 753-2405 7031894-5777 visalmc 8001282-5628 Ham Radto England c/o R S G B fl 153 I ARI Lambda House Cranborne Road AMERICAN RELIANCE INL. Potters Bar 9241E. VALLEY BLVD. ROSEMEAD. CA91770 Herts EN6 3JW England TEL: (818) 287.8400 FAX : (818) 287.8855 JUNE 10: OHIO: The Goodyear ARC'S 23rd annual Hamfest THROUGHOUT 1990 the Major Armstrong Memor~alAma- and Family Picnic. Wingfoot Lake Park. Akron. 8 AM to 4 PM. leur Rad~oClub IMAMARC)will sDonsor events commemorat- Famlly admlss~on$4.00/advance; $5.00 at gate. For tickets and Ing Malor Edwin Howard Armstiong's achievements in the lnformation contact William F. Dunn. WBIFM. 4730 Nottlngham field of radio broadcasting. The club is seeking other Ama- Lane, Stow, OH 44224. (216) 673-8502. teur operators around the world who are willing to research Major Armstrong's accomplishments and become official WRITE FOR JUNE 10: PENNSYLVANIA: The 17th annual Central PA Ham MAMARC special events stations. Major Armstrong was a and Computerfest, sponsored by the Milton and Central oloneer responsible for the creation of Wideband FM and the Susquehanna ARCS. Winfield Fireman's Fairgrounds. 8 AM inventor of ihe suoerhetrodvne receiver. If vou are interested to 5 PM EST Donations $4/gate. For information Jerry Wil- qn partlclpatlng &d oecom'1ng an off c~al AMA ARC speclal liamson, WA3SXO. 10 Old Farm Lane, Milton, PA 17847. (717) event statlon conlact Barry Groupp. NZHDW. MAMARC, c/o FREE 742-3027or Bob Stahl, KOJKR, 452 Fourth Street. Northum- 100th Blrthday Commlttee. PO Box 581. A plne NJ 07620 berland. PA 17857. 1717). . 473-7050. Please SASE. JUNE 16: NEW JERSEY: The Raritan Valley Radioclub's 19th YOUTH LINK NET. Open to all Hams under age 18 Satbr- BOOK annual Hamfest and Computer Show, Watchung Hllls HS, days at 2000 UTC 28425 MHz For more ~nformal~oncon- Warren. Gates open 8 AM. Lookers $4 donation. Spouse and tact Nel Control. deorae Mannlnq. WB5NMH. 602 Glendale k~dsfree. For further information call Dave. KAZTSM (201) St. Burkburnett. TX 78354 - 763-4849 or John. WA2C (201) 968-5070. CATALOG FREE 1969-90 Florlda two meter repeater directories are cur- JUNE 16-17: MONTANA: The Valle ARC of Glas ow IS spon- rently being distributed by the Hernando County Amateur sorlno a Fatner's Dav Ham Plcnlc Antact Lmda iray, N7FSH Radio Assn, of Brooksville, FL. Ask for one at any official (406r228-2324. . Florida Welcome Center or SASE to Repeater Directory. Hernando County ARA. POB 1721. Brooksvllle. FL 34605.1721. JUNE 17: MARYLAND: The Frederick ARC'S annual Ham- Ham Radio's Bookstore test on Father's Da Frederick County Fairgrounds. 8 AM to AMATEUR EXAMS, ~~l~ 14, september8, ~~~~~b~~ 17, st. Greenville, NH 03048 4 PM. Admission $4. Spouse and kids free with one paid Mary Medical Center, 3333 No. Seminary Street, Galesburg. admission, For information Ernie K3VVV,PO Box IL 61401. 12 Noon to 2 PM. For information contact Larry ; 589. Mt. Airy, MD 21771. -- ~~I!er,~~?M, 1436 Brown Avenue, Galesburg, IL 61401. JUNE 17: INDIANA: The Lake County ARC'S annual Fathers' Day Hamfest, Industrial Bullding of Lake County Fairgrounds. Crown Point. 8 AM to 2 PM. Admission $3.50. For informa- Monthly Ham Exams. The MIT UHF Repeater Association tlon contact Ken Brown. KESTC, 918 Chippewa. Crown Point, and the MIT Radio Soclety offer monthly ham exams, all IN 46307. (219) 663-5035. classes Novice to extra: next-to-last Wednesday of each MlNINEC USERS month, (JUNE 20) 7:30 pm, MIT Room 1-150, 77 Mass Ave- JUNE 17: MICHIGAN: The Monroe County Radio Communi- nue. Cambridge. MA. reservation requested a couple of days cations Association's 1990 Hamfest. Monroe Countv Fair- in advance, walk-ins welcome; call the shack (617) 253-3776, Tired of counting pulses? grounds, Monroe. Tickets $3ladvance; $4/gate. Handi park- or Nich Altenbernd (617) 437-0320. Exam fee $4.95. Bring copies of your current license (if any) and Certificates of Com- In and wheelchair accessible. Contact Fred Lux. WOBITZ. glves you all the power of MININEC, full Box 982. Monroe, MI 48161. (313) 243-1053. pletion (if any), two forms of icture ID, and a completed form ELNEC ~8 610, available from the FCC! (617) 770-4023. plotting and analysls features, easy menu-driven Input, JULY 4: PENNSYLVANIA: Firecracker Hamfest sponsored by and n~ frrnslclO with DuI~!Just tell ELNEC which the Harrisbur RAC, Bressler Picnic Grounds, Harrisburg. AMATEUR RADIO CLASSES: For those people interested in wlre to place a source or load on, and the dlstance from Starts 8 AM. idmission $3. Contact Dave Dormer, KCJMG obtaining a Novice (basic level) Ham license or upgrading to the end (In percent), and It's there to stay. Use 171n 939-4957 for reservations. TnchlGeneral the Chelsea Civil Defense. in coooeration with &A uirllo club will soonsor Amateur Rad~oCommunlca- ELNEC's powerful features to add, delete, and modify LAUREL ARC monthly (except December)Amateur exam ses- cons ci&;ei iien~n~gic~helseaHlgh School startlng sources, loads, wlres, and ground media, and the slons for all llcense classes No fee IS charged Pre- MARCH 7, 1989 For more ~nformallonwrlte Frank Masuccl, sources and loads stay where you put them - not on realstratlon IS reaulred Call (301) 725-1212. Maryland Rad~o KIBPN. 136 Grove Street, Chelsea, MA 02150 Please enclose some obscure "pulse number" that moves every time a Center, 8576 Laureldale Drive, iaurel, MD 20m your telephone number wlre is changed. ELNEC has a host of other features to make antenna analysls fast, accurate, and easy. Llke drue current- for phased array analysls. ChanOc wire lengths wlthout recalculating end cwrdlnates. And much more.

Here's the best news: ELNEC Is just $49 postpaid (USA, Canada, Mexico). Two versions are available, optimized for coprocessor or non-coprocessor systems Roy Lewallen, W7EL P.O. Box 6658 Beaverton, OR 97007 WEATHER SOFTWARE

ACCU-WEATHER FORECASTER is a menu driven program that allows the user to tap Into Accu-Weather's extensive computerized database. In addition to Accu- Weather's forecasts, you can get hourly updates from Nat~onalWeather Service Offices nationwide. Maps, graphs, pictures, charts, and narrative descriptions are just paR of what can be downloaded to your MS.DOS computer. To save telephone and hook-up charges. tell your computer first exactly what information you want. Then call ACCU-WEATHER; the computer will download the files you want and save them to disk. lnformation can be Say You obtained for the entire United States or a specific geographical region. Several different services are available from ACCU-WEATHER. Price varies with the service and ttme of day that the computer is accessed. Add $3.50 for shipping and handling. MC-IBM $89.95 Saw It in 0 MC-MAC $89.95

Please enclose $3.75 shipping & handling HaM as

GREENVILLE, NH 03048 603-878-1441 aR L

78 Ham Rad/o/June 1990 KENWOOD

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Also displiryrng the poprtlrrr trcces.\ories ne~t1c.dto cnttiplc~rr~cr HAM STATION . . . ARRL PUBLICATIONS AEA PRODUCTS AMPHENOL ALPHA DELTA ASTRON AUSTIN ANTENNAS AVANT1 HEL1)EN BENCHER B & W DAIWA ALINCO HUSTLER KLM LARSEN MIRAGE ROHN TEI,EX/HY-GAIN TOKYO HY-POWER LABS DIAMOND 'TRAC KEYERS VIBROPLEX WELZ ETC.

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SURER PERFORMANCE BATTERIES UPDATED SUPER ICOM SUPER YAESU SUPER ICOM BP.7S. 132 volts. SUPER YAESU FNB-4SH. 12 volts. l?OO~na tr~l)letlie capac~tyof the 1000ma. docrt)le the capaclty of the Icom BP-7. Sw outpul Yaesu FNB-4 5 wall output Rap~d All Jerrold, Oak, Hamlin, Zenith, SUPER ICOM BP-BS. 96 volts. charge orily S71 00 SUPER YAESU FNB-3s. 96 volts. Scientific Atlanta, and more. 1200n1a. 50 more capaclly than lh~!lcorn BP-8 1200ma. tr~plethe capaclty of the Both are rap~dbase charge only, or Yaesu FNR-3. 3 5 watt output. 60 Day Money Back Guarantee sl~deIn wall charger. 4 Inches h~gh Rap~dor wall charge 56500 BP-7S or BP-8S S65 00 Botli are perfect for the 03. 09 and Shipment within 24 hours 727 serles rad~osand are 4 Inches SUPER KENWOOD Exact replacement FNB-2 Nlcad pack high VisalMC and C.O.D. SUPER KENWOOO PB.25S/PB.26S. 8 4 for Yaesu FT-4MR 1207R1208R1708R lmea for: volls. 9001n,r dolll~lvth~ ciil)ac~ty S?2 50 Kenwmd PB-25. 25H. 26 525.00 of the PB~25lPB-26lor the 25001 lmm BP-3 318.95 WE WILL BEAT ANYONFS PRICE ~W/~SMI/XMI Ctlarge with ellher SPEAKERIMICS lmm BP-5(SCIDIIIR) 324.95 No Illinois Orders Accepted the standard wall charger or drop IcOm HM.9 335.00 lmm BP-7 (500mal 529 50 tn charqer 3 ~ncheshlqh S6500 Yaesu MH12A2B 331.00 Imm BP.8 529 50 Full line for Yaesu 4111811 1470, FNB-10111/12114 avallable Add M W sh~polnqRhandl~ng for llrsl pack CT resldenls add 8 lax Complete line of NlCAD packs for Icorn. Kenwood. Yaesu. Tempo. Sanlec. Azden. Cordless Telephories. Akallne. Nicad 8 Gell-Cells All NlCAD packs Include 1 year guarantee Comrnerclal Rad~oPacks avallable For all your battery needs. wrlte or call today lor a complete catalog Dealer Inqucrres lnvlted .,l;,lll ,!\ ,{;.%$!L, i,,,;::,*,*., m \iilllllPemW Im. vtu 149 Palmer Road Southbury CT 06488 (800) 634-8132 In CT 1203 264-3985 FAX: 12031 262-6943

fl 160 Ham Radio/June 1990 79 I Advanced Antenna Turn your IBM PC or compatible into a com lete I Isfow ranTV nstem YOU dont need anotfer I erto ssrid and recewe Images in up to 64 1 Analysis Program d gray Works wlth most popular qraphics I I ELNEC Is an all.ncw. porsdul. easy-to-use antenna nnslyrls -ram Anlsnne aercrlpllon and changw am la$l and easy

ELNEC 18 convlelely mnudrlvan. All anlanna dssolptlons and Tutorial Caseme chenws nrr done wllhoul extllng the program. Add. delete. modlly sources, lasds. and rrltcs wllh Iw heyslrohcs.

ELNEC user the powerol MININEC, ye1 cowlelely lrwr yw lrom thsle- dl~~schore01 cmnllng "pullst" Slmply tell ELNEC whlch wlm sna where you wan1 a source or load to go - ELNEC puts It there and keeos I1 them. even when wtre9. sourns and loads are added. drlel

ELNEC runs on any PC*ompallble comwler wllh at leart36Ok ol RAM. and CGA, ECA. or Hcrcules Plols prmt on Epson-compallble 8 9 or 24 pin ~rlnlcrsTwo vcrslons aro avallablc. o~llml~edlor svs- lems woth and w#lhoula roprocorqor

ELNEC 1% an Incomparable valw 11 only S49.W poalpald (USA. Canada. end Mextco) Spoc~lycoprocessor or nonloprocessor version. Order or wrllo lor more Inlormallon Irom.

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r/ 167

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CRmEK CORPORATlON All =ln~~~~.inptrrnlo~FO 2?1krem?rnndSl.lllll1.r$It>lbchMmt lkwrrn!~rxcernt trnlklt#n 1"~l~nl~nst~lalo~r(>laled t U ', ~B~~WRIEholt) h-rnd$nmvtet U V $10.78 and rerslnnf U boltl YO 3.0 lealures tmproved accuracy, faster compulalion. I)IVI ,10r1 .L~II~IIIA!I~OWV'W~I~ON opllmtzatlon ot s~ngleYag~s over ground, and slacked Yag~sIn free space YO 3 0 IS 2-4 tlmes more accurate 4'5ALSO AVAILABLE and 20.65% laster lhan YO 2 0 Opt~m~zea Yag~ a1 11s 2351123il Cryrtal DI .ft Myerr. FL 33907 PO &,OoIrr,.rl MV. II 3>9(~61r', The incomparable FO-25 and FO-33 exact tnstallat~on holghl for lmpmved F!B and SWR. TOU FREE 1-800-237-3061 S IACfiNG IRAMELPOWEfl OIVIOERS Opttmize take-011angle Account lor antenna ~nteract~on

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Ham Radio/June 7990 81 GET YOUR ADVERTISER'S INDEX AND READER SERVICE NUMBERS Listed belowarethepageand readersewice numberforeachadvertiser inthisissue. Formoreinformationon their products. select the appropriate reader service number make acheck mark in the space provided . Mail this form to BAGS PACKED! ham radio Reader Service. I.C.A., PO. Box 2558. Woburn. MA 01801 . Name Call

Address .- NASHVILLE 'go! City -State .Zip *Please contact this advertiser directly. Please use before July 31. 1990.

is almost here! We'd like to see your company listed here too . Contact Arnie Sposato at 516-681-2922 or FAX 516-681-2926 to work out an advertising program tailored to suit your needs. SBCA / STTl READER SERVICE # PAGE # READER SERVICE # PAGE # -112 -Ace Communications. Monitor DIV ...... 27 -129 -Link Comm ...... 58 presents -165 -Ace Systems ...... 80 -143 .Madison Electronics Supply ...... 69 -117 -Advanced Receiver Research ...... 46 -150 -Madison Electronics Supply ...... 72 105-AEA ...... 13 .Maggiore Electronic Lab ...... 53 -131 .Aluma Tower Co...... 58 -162 -Glen Martin Engineering. Inc...... 33 NASHVILLE -104 MFJ Enterprises 8 * -Amateur TelevisionQuarterly ...... 66 ...... -119 .AMC Sales. lnc ...... 46 -189 -Missouri Radiocenter ...... 83 -154 -American Reliance ...... 77 -122 -Monitoring Times ...... 21 SHOW 'go! -116 -Ampire ...... 39 -142 -NCG ...... 69 -152 -AMSAT ...... * .Nemal Electronics...... L -115 -Antique Radio Classified ...... 39 -134 -Nuts 8 Volts ...... 60 Opryland Hotel -108 - Astron Corp ...... 20 * -Omega Electronics ...... 58 -109 - AVCOM ...... 53 -170 - OPTOelectronics ...... 84 Nashville Tennessee * - Barker8 Williamson ...... 21 -160 - Periphex Inc...... 79 - Barry Electronics ...... 58 -149 - Pac-Comm Packet Radio Systems, lnc ...... 70 July 9.10.11. 1990 -132 - Bilal Company ...... 58 -126 - Palomar Engineers ...... 54 -124 -Bird Electronics ...... 54 -151 - Ramsey Electronics. Inc...... 75 Plan to Attend - Brian Beezley. K6STI ...... 80 -141 - Thg RF Connection ...... 66 * - Buckmaster Publishing ...... 46 -161 - Rutland Arrays ...... 33 The World's Largest -121 - Buckmaster Publishing ...... 51 -166 - Rutland Arrays ...... 80 -138 - Buckmasler Publishing ...... 61 * -SIGN ON ...... m and Most Exciting -153 - Buckmaster Publishing ...... 77 -123 -Software Systems ...... 71 -111 - CBS Sales ...... 26 -167 -Software Systems ...... 80 SATELLITE TV -118 -Communication Concepts. Inc ...... 46 * - STTI ...... 82 -102 -Communications Special~sts...... 1 137- STVIOnSat...... 62 TRADE SHOW! -130 -Creative Control Products ...... 58 -147 -Synthetic Textiles. Inc...... 70 -163 -Cryslek Crystals...... 80 -155 -TeI.Com ...... 79 -127 - Cygnus-Quasar Books ...... 54 133- Unadilla ...... 60 * Hundreds of Exhibits! -Digital Digest ...... 33 * -Universal Radio ...... 61 -138 - Doug Hall Electronics ...... 65 -148 -Vanguard Labs...... 4 ~rUp-To-Date Seminars! -128 - Down East Microwave ...... 54 -125 - VHF Communications ...... 54 * Entertainment! 159-Electronic Engineering ...... 79 113- Wacom Products Inc...... 27 - Engineering Consulting ...... 72 -145 - W 8 W Associates ...... 71 * Fun For the Whole Family! -146 -GAP Antenna Products...... 71 - W5YI Marketing ...... 39 144- Gilfer Shortwave ...... 69 -135 - W9INN Antennas ...... 61 -103 -Ham RadioOullel ...... 6 -168 - Wilam Technology ...... 80 * -Ham Radio's Bookstore...... 42 * -~aesuUSA ...... CIII -106 - Hamtronics. NY ...... 15 -110 - E . H . Yost ...... 27 * - Hamtronics, PA ...... 65 139-ZCo Corporation ...... 65 For Details Call 114- Henry Radio ...... 3 -101 - ICOM America . Inc ...... CII PRODUCT REVIEWINEW PRODUCT National Satellite Shows - Indianapolis Hamfest ...... 66 -120 - Jun's Electronics ...... 51 -306 . AEA ...... 81 -107 - Kantronics ...... 16 -302 .Ameritron ...... 61 1-800-654-9276 -140 - KComm. The Ham Center ...... 66 -301 .Cushcraft Corporation ...... 81 or - Kenwood USA Corporation ...... 2 . 5. CIV -304 .Fundamental Services ...... 81 -158 -Roy Lewallen, W7EL ...... -305 .ICOM America . Inc...... 81 702-367-1471 -164 - Roy Lewallen, W7EL ...... 80 -303 .Roy Lewallen. W7EL ...... 81

82 Ham Radio/June 1990 DEPENDABLE SERVICE

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/no dmower.. L . and Yore! Automatic Repeater FT-212RH Shift (ARS):Enables selection of repeater Frequencv Svnt hesized transmitter offset VMFIUHF FM autoniatically when Transceiver tuned to a standard The compact. versatile repeater subband. FT-212RH is a 45 watt. 2 Programmable meter mobile that boasts Scanning: Scans band. a lot more than just high I band segment or

power. Inside its sturdy com- --~-memories. - ~ Scan~ auto-resume pact frame hides an impresive with carrier drop or after Freqocnc~R:inge: 140-174 array of performance features 5-second pause. plus high reliability.. .like MHz on receive (144-148 MHz 18 general purpose memories: TX-Modifiable for MARS Tuning Steps: Operator one-touch call channel memory: and CAP). Specification< selectable steps in 5, 10, 12.5. two scanning range memories: guaranteeti on aniateur bands 20 ant1 25 KHz increments. CTCSS on any of the 37 only. CAT System Control: standard tone frequencies Power 011tput:45 watts Provides for external control may be programnied into any output with selectable 5 watt of VFO frequency, mode and memory channel. Choice of low power. memory functions from standard. or optional. high CTCSS: Accc\\ any of the operator's personal computer. performance tone encoding 37 standard CTCSS tone fre- Amber Backlit I.,CD Display: microphones. The FT-2 12RH quencies. plur 97.4 Hz can Automatically controls the and its 35 watt UHF counterpart, be displayed, selected and brightness of the display back- the FT-712RH are packed with programnicd into any memory lighting and pilot lamps. state-of-the-aft refinements.. . for trans111iwinn. Tone Encoding 3Iicrophone: power and more! I0RIemories: Each memory Choice of standard. or optional \tore\ eithcr programmable high performance DTMF tone repeater sh ~ftor independent encod in(. micro~hones. L TX and RX frequencies. Digital Voice System (DVS-I): Optional sytem which allows local and reniote digital voice recording and playback. 1111 (rnotlil'~:~hlelor hljlRS and CAP): 430-450 h1t1? on 7(lcrn. * I'o~c-r For inli)r~nationtin thew anti Y:ir.su'\ full l~nc Outpul: 50 \vatt\ on 2m: 40 watt\ on oiprc>ducfs,cull r>ur liri.r;~turedesk toll-free ;]I 70cni. Sclcctahlz 5 \\,art\ lo\+power on I (XIHI1 999-2070. hot11 h;rncl\. Full l)upleu ( roc\ Itancl Oprratic~n: I)~titlKrrri\c: .('-1'!%S 1:ncrrcleil~ecoclc: "=T-4700RH Itrri~~rtt*<'c~ntrol Kit Inrli~clecl: 41nher l',:icklit

u TI' * :I1- ! !.('I) i)i,lil:l! ;ind conrrol, w 1111tlimmcr\\vitcli. 20 3lcrii11rirs:. I)ui~l \ntt~ntii~ l'orlz: Trunk Mountahle l'r~r~r:ttiini:aI)l~Scan~iitl~: \lll-l5('R hlic FM Transceiver \tantl;~rd:\Irj-Isi)x Iltcol~tional. YAESU Pcrtort?rarli~zil~tllolct io~!r/~ronlisc. c 1990 Yaesu USA. 17210 Edwards Road Cerr~los.CA 90701 Speclf~cat~onssublecl lo change wlthout notrce