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137 M«nch«8t*r Driva FloriMint, Colorado flOStfi (719) 8670650

Ham help

Number 10 on your Feedback card

We are happy to provide Ham Help listings free on a space available bazas. To make our job easier and to ensure that your listing is correct, please type or print your request clcarty double spaced, on a full I8 i/2~ x iH sheet of paper. You may also upload a listing as E-mail to Sysop to the 73 BBS Special Events Message Arena (2400 oaud. 8 data cms. no panty 1 stop bit (603) 924-9343), Please indicate if it is for pub it-cation. Use upper- and lower-case letters where appropriate. Also„ print numbers carefully—-a 1. for example, can be mfef&ad ¡is the letters J or or even the number 7. Specifically mention that your message is for the Ham Help Column, Please remember to acknowledge responses to your requests. Thank you for your cooperation.

I would like ta get information arid the addresses of manufacturers of amateur radio equipmenl I am in the process of setting up a smaii retail business in the Oklahoma City area to hefp the amateur community I am looking for reputable companies that give good service on their equipment, Gten Coffins. 312 Hunter Hill, Oklahoma City OK 73127.

I need information on a good 2 meter base rig, I do not want a HandMalki or mobile; I need something that will handle CW, SS6 and FM. I also need information as to where I can get a small 20-10 meter beam, as I have limited yard space. Please send replies lo Rev John J. Kubenski. Sr., 1102 \2th Ave, SE. Jamestown ND 53401,

Does anyone know oi ariy amateur radio soil ware lor the Coco III computer? \t would not matter if it was just for BASIC, DISK BASIC or OS9 Level I or IL I would like to use my Coco 111 for WeFax, RTTY. CW and whatever else in radio communications, If you have any leads or information, please help David Guess, 121 US. 31W Bypass ApL 6, Bowling Green KY 42101.

1 need to build an inexpensive, grapefruit-sized, mains-ope rated power supply, 12V (AC or DC) at 60 amps. All help/info/advice gratefully acknowledged. Alex Funke KC6IWR: 1176 Fiske St.r Pacific Palisades CA 90272

if anyone has information on modifications that can be made to the "HAlh DS300Q KSR terminal to enhance its operations, especially a mod that could provide an ASCII output as messages are displayed on the screen, please contact Eric A Stokes Sr. WA8ZJY. 11415 West Pkwy„ Detroit Ml 43239.

NEEDED: Service manual for a HEATHKIT Multi-Speed Servo Chart Recorder Model IR-1BM Series 02240 i also need chart paper $445-19 for the same machine J wrlJ pay tor copies and postage. Thanks John EtienburgH 6009 Fail Creek Rd,r Russeftvltle TN 37860.

fl^k Number 11 on your Feedback

Dealer directory card


Factory authorized dealer! Yaesu. ICGM, Ker^ wood, AR^L RuttcaiiOrtS CsllbOOk, ARE Ham-jLnv. AEA. Kantroncs Air cation. Cushcraft, Hy* Gain, Hail Sound. Siantfard Amateur Radio, MFJ, Hustler, Diamond, Butternut, Astron, Larsen, ind much more, DELAWARE AMATEUR SUPPLY, 71 Meadow Road, New Castle DE 19720. (302) 32*7728,


North Jersey's rawest Two Way Radio and Electronics Dealer is now open. Safes of Ham, Business, Marine snd C.B. two way equipment as well as Scanners Shortwave, Electronic Kits. Antennas, Books, Cable Boxes and more. Friendly service and low prices. Advanced Spz-d at ties, 114 Essex Street, Lodi NJ 07644. {201} VHF-2067,


North Jersey's oldest and linesi Shortwave and Ham Radio Deafer. Three minutes from Garden Stats Pkwy and NY Thruway Authorized Dealers for AEA, Alpha Delia, DiarrcHid, ICOV. Japan Radio Company Ken wood. Vecironics. Yaesu Ham Saies. Lee WK2T GJLFER SHORTWAVE, 52 Park Ave,T Park Ridge NJ 07656. (201) 39V7B87.

NEW YORK Manhattan

Manhattan's targesl and only Ham Radio Store, also full lire of Business, Marine. Aviaiion, Shortwave Radios and Scanners, and Cellular Phones and Beepers. Large selection ol Books^

Antennas, Test Equipment, coaxial cabfe and aarls, Full Service Repair Lab on premises. Our 44th Year...We cany all major lines: MOTOROLA. tCOM. KENWOOD. YAESU. BENDIX KING. ASTRON. AE-V SONY, PANASONIC, MFJ. CCTV CAMERAS AND MONITORS, BtflO WATTMETERS, FREQUENCY COUNTERS. SCANNERS- HYGAINh VlBROPLEX. HEIL, CALLBOOK,, ARRL OTHER PUBLICATIONS, Open 7 days M-F. 9 6 p.nv: Sal.. tQ-5 p.m., Sun, 11-4 D.m. We ship Htortdwiffe. Call. Fax. or wnie for information and prices. Y6ur one Source lor HAM and Business Radios SAflRY ELECTRONICS, 512 Broadway. New York NY 10012. [212} 925-7000. FAX (212)925-7001.

OHIO Columbus

Ceniral Ohio's lull-line authorized dealer tor Kenwood, 1COM, Yaesu, Alineo, Japan Radio, Standard. AEA. Cushcrafi, Hustle*. Diamond and MFj New and used equipment on dismay and operat-orsal in our new 10.000 sq. ft. taoJrty. Large SWL Department too UNIVERSAL RADIO, 6830 Americana Pkwylf Reynoldsburg (Columbus) OH 43065, (614) S66-4267,


Authonzed factory sales and service, KENWOOD, [COM. YAESU, fealunng AMERÍTRON, B&W. MFJ, HYGAIN. KLM CUSHCRAFT, HUSTLER, KANTRONICS, AEA, V1BROPLEX, H&U CALLBOOK. ARRL Publications, and much more HAMTRON1CS. INC., 4033 Brownsville Road, Tremóse PA 19047. (215) 357*1400^ FAX (215) 355-0958. Sales Order 1-flQtM26-2-830, Circle Reader Service 238 for more information,

Deaiers Your company name and message can contain up lo 50 words for as little as $420 yearly (prepaid). or S2t0 icr six months (prepaid). No mention of mail-order business please. Directory texi and pay men* must reach us 60 days in advance of publication. For example, advertising for the April '92 Issue must be in our bands by February 1sI. Mail lo 73 Amateur Radio Today, 70 Pile. 202 N, Peterborough, NH 03458


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73 Amateur Radio Today* November, 1994 39

73 Review

Number 12 on your Feedback card by Dave Petaez AH2AR/5

Btlal Company 137 Manchester Or. Florissant CO S0Ô16 Telephone; (719) 687-0650 Price Class: $59.95

The Isotron 40

The neighbors might think it's a futuristic bird feeder, but it's really a compact, horizontally-polarized 40 meter antennal

Lefs face it ... a 40 meter antenna that is small enough to fit inside a trash bag probably puts out about as much signal as a dummy toad, right? Also, if it looks unconventional, it must not work as welt as a normal antenna, right? Surprise! Both of these premises are incorrect! The Isotron antenna is an excellent example of one that shouldn't work because it simply doesn't "look" right ... at least this is what \ thought before actually buying one of these antennas. But work It does! Much to my surprise, the Isotron 40 meter antenna has performed so well it has now become a part of my permanent HF installation. As long as the antenna is electricaily correct, and laws of physics aren't broken, many unusual antenna designs are possible. And this antenna has proven to be no exception. Let's take a closer look at this extremely compact HF antenna that could be the answer for hams with antenna space limitations.

In business since 1980, Ralph Bilaf WD0EJA has actually designed six different Isotrons for 160, 80, 40, 20, 15 and 10 meters, A search for the "textbook' name for these antennas came up "empty." I discovered that Mr Bilai coined the term "Isotron" to describe his design which is really quite unique.

Construction t found the instructions provided were excellent. Assembliy time is about 40 minutes, start to finish. The only tools that are required are a screwdriver, pliers, and a small wrench. You must purchase a five-foot mast section in order to fully assemble the antenna, as the mast section is not included. There is no need to break out the soldering gun or wire stripper. The SO-239 connector is pigtailed at the factory and the coil assembly is pre-wound, stripped, and tinned. The total part count is 10, and all fastening hardware is stainless steeL


Wayne would indeed grimace. 1 decided to mount the antenna for testing in the attic, knowing full well of the E-Re!ds that would be present (another good reason not to run the amp!). This installation was to keep myself in good graces with the XYL, As we had just moved into a newly-constructed home, 1 had earlier ruled out putting up a dipole, as the closest "attachment point" for a wire antenna was a transplanted sapling that I had earlier mistaken for a large Texas weed. So up went the Isotron,

Isotron Antenna

Photo A. The Isotron 40.


The most challenging part of the assembly is the tuning of the antenna to find its resonant point Mr. Bifal has compiled a detailed step-by-step process to make this "black art" less tedious. In fact, the instructions are complete enough so you do not have to rely on a noise bridge to adjust the antenna's resonant point. Tuning this antenna is a matter of pivoting a capacitance hat thai is attached to an aluminum rod from the vertical and past the horizontal, rotating the rod to the "front" of the antenna. — The instruction booklet contains some neat tricks and shortcuts on how to arrive at the desired resonant point. These helpful hints are a product of a whole lot of ''corporate memory" that greatly assists the new Isotron purchaser in avoiding the potential pitfalls of bringing the antenna to resonance. For in-band utilization, no trimming of the coil is ^^^ required; however, the instruction manual explains the procedure for trimming the coil if the antenna is going to be used for out-of-band activities (MARS CAP FAA etc).

Once the resonant point is found, you will notice a dramatically steep resonance skirt,. In my installation \ have a minimum centered 1.1 to 1 VSWR and a usable 3 to 1 VSWR about 150 kHz up and down the band, More typically, a 250 kHz tuning range can be expected. This "usable" tuning range wili vary, depending on the installation environment An Isotron in the clear, as opposed to one located next to metal attic ductwork, will behave differently. Past the usable range, the VSWR ends up going off the chart very quickiy.


My first perception after tun^g the antenna was that 1 had the transmission line hooked up to an in-the-cfear dipoie. \ listened up and down the band, and the usable bandwidth was very active with many signals. The atmospheric noise level seemed to be a bit quieter than "normal" Frankly, I was expecting to hear only a few of the "big guns" on the band, but 1 was pleasantly surprised to hear an active band. After one final check of the VSWR, I broke into about a half dozen QSOs. E was also surprised that I could work emt This was not expected, especially with my compromise attic installation. I tried another "test" later in the week with some friends who were about 40 miles out {ground wave), it was interesting to note that the staiion on the other end was experiencing a high noise level due to a distant thunderstorm. He was using a long-wire antenna. and we both were running about 100 watts.

— Up to three different Isotrons can be connected in parallel; however, the manufacturer recommends the utilization of a noise bridge, as mutual coupling causes the overall impedance to become an average of the three antennas* making the tuning process extremely complicated.

How Does it Work?

I have successfully kept an active 40 meter schedule with KK4LW/7 who lives in Fort Collins, Colorado. Tve been amazed that we have been able to consistently communicate from Dallas using an attic antenna about the size of a small Texas watermelon. Just remember one thing: The "feed point" does not require the placement of bird seed between the coif and the plates. Q

Tve been amazed that we have been able to consistently communicate from Dallas using an attic antenna about the size of a small Texas watermelon


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