And G Electronics Of Maryland

Various products formerly manufactured by Microlog are now available from G and G Electronics of Maryland. The ART tT AIR-1f and AlR-1 software are among these products. The SWL allows you to copy worldwide shortwave radio signals on your C-64/128. The SWL alone is $64. The AIRDOS disk, which allows you to to save data, is Si5, The MORSE COACH is $49,95. Package price is $99.95. G and G Electronics of Maryland. 8524 Dakota Drive, Gaithersburg MD 20877; 301 -258-7373L Circle Reader Service number2i6


The AR-640GP Automatic Cable Tester from American Reliance, Inc., tests cables and wire assemblies of up to 128 test points, and it is expandable to a total test capability of 512 test points by the addition oi plug-in I/O boards. It has a built-in parallel printer port, cable included, so that it can print test results and lists of wire The AR-6400P sells for $995.

The 6401 FX Universal Test Fixture is available as an option for $100, Connectors on the fixture include two each of 9. 15. 25. and 36 pin "D" types, and 37 and 50 pin Centronics types. American Reliance Inc.. 9241 E. Valley Blvd., Rosemead CA 91770; 818287-8400. Circle Reader Service number 209.


Now among the many electronics kits and assemblies A & A Engineering has to offer, is ihe DigiCOm >64 by Barry N. Kutner, M,D r W2UP [see his article in the August 1988 issue ot 73). The Digicom >64 is a sott ware-based packet radio system for the Commodore 64 which emulates the functions of a TNC. The PCB only is £10.65; the PCB and disk. S14 95: the kit with PCB and disk, $49.95; assembled board, $79.95; and disk only, $6. A & A Engineering. 2521 W. La Palmat Unit K, Anaheim CA 92801; 714952-2114. St as J. Andrzejewski W6UCMr President. Cirde Reader Service number 215.

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Tech tips

Non-Liquid Fix for the C-64 Stutter

With alt respect to Bill Clarke WA4BLC, 1 believe I have improved, on his suggestion, about the best way to ftx the Commodore 64 with a stutter problem.

As Clarke mentioned in his anicle (73 Magazine, July 1986). the C-64 has become a fixture around the ham shack. It serves such important purposes as word processing. logging. QSL design, and HTTY communications Such a hardworking, useful instrument is bound lo experience the occasional service problem, and one of the most common is the missed or repeated character.

The problem is the contacts under the keyboard develop a nonconductfve coating that causes the stutter malady The results take different forms, but they are usually aggravatrngiy apparent in embarrassing typographical errors on FITTY, or frequent use of the delete key in word processing.

"Remember the Golden Rule-keep water away from electrical circuits."

board away from the kitchen sink and possible short circuits.

By rubbing the eraser over the shiny contacts on the circuit board, and after the keyboard is reassembled, it will work as good as new

So enjoy using the C-64 in all of its many versatile applications in the ham shack. And if and when the keyboard develops the stutter problem, feel confident that the user knows what caused it and how to fix it. Also remember that this has probably saved (he user S30 to S1D0, for the technician repair cost, each time it is performed

Dust remover spray (available at Radio Shack) and the Pentef Clic Eraser make a greal team when it comes to cleaning Ehe Commodore 64 computer Use the spray to remove the inevitable accumulation inside the 64. and use the eraser to clean the contacts on the keyboard circuit board as directed in the accompanying article.

rr at a

To remedy the situation, Clarke suggests the use of a mildiy abrasive bathtub cleaner. Remembering my electrical basics, it goes against my grain to coat a circuit board with a liquid solution that is also an excellent conductor. Remember the Golden Rule of keeping water in ail forms away from elect ri-cai circuits? So when I developed a similar probfem with my C-64, I started looking tor an alternative fix.

II followed Clarke's instructions about removing the three screws on the bottom, disconnecting the plugs and wires to the keyboard, and unscrewing the 23 tiny screws that hold the keyboard together. Carefully lifting the circuit board, I turned it over to reveal the green side with the contact points that require cleaning to fix the problem.

Here is where Clarke and J differ. Rather than taking a wet approach, my fix involves using a very dry pencil eraser tn the same way used to remove pencil marks from paper. ) recommend a Pentei Cite Eraser, which is a white, pencil-shaped eraser m a plastic holder. It is easily found at most office supply oullets The eraser works so well on pencil mistakes {like they were never there), that I suspected it would clean the circuit board quite well, loo Guess whai? It does the job perfectly, quickly and keeps the

Welcome Newcomers

Refer to the October 1988 issue, page 4. Look in the ''Glossary" for the definition of frequency. Frequency is measured in cycles per second. One cycle per second is called one Hertz (Hz). Frequency is not given in meters per second, commonly termed Hertz."

Also, refer to the definition of the electromagnetic wave spectrum on the same page and in the same section of the October issue. The last line should read that the microwave portion of the spectrum is typically set at 1,000-300,000 million cycles/second." The word "million" was left out— which makes quite a difference!

Antenna SystemsSeptember 1988

A minor typographical error in this article by John Lawson W3ZC, on page 11 pplO. operator j is incorrectly identified as the square root" of i. and, unfortunately, appears quite often in engineering The square root of 1 is obviously stitl 1 Operator j is actually the square root of MINUS 1, and as it is physically impossible to quantize a square root as a negative number, it is properly referred to as an "imaginary number' HI


We've had so man\ phone calls from people warning our famous 73 code tapes ihai v-eve decided to bring them back! hn j u about rinit you dust aff that keyer and sharpen up y*w anie skilh? Order now.,.


5 wpm-This is the beginning tape, taking you through the 26 letters. 10 numbers and neces-sar> punctuation, complete with practice every step of the way. The ease of ¡earning gives confidence even to the faint of heart

'The SlicKier

6+ upm-This is the practice lape for those w ho sur\ ived the 5 \tpmtape. and it >alsci the tape for the Nos ice and Technician licenses. It is comprised of one solid hour of code. Characters are sent at I? u pm and spaced at vv pm Code groups are entirely random character sent in groups of five—definitely not memorizable!

"Back Breaker"

13+ upm Code groups again, al a brisk 13+ wpm so you'll be realt> at ease when you sit down in front of a steely-eyed volun teei examiner who starts sending you plain language al only 1:3 per. You'll need I his extra margin to overcome the sheer panic universal in most test situations. You've come this jar, so don't get code shy now!


20 -1- wpm ^Congratulations! Okay, the challenge of code is what 's gotten you this far, so don'iquit now Go for the Extra class license We send the code luster than 20 per. li s like wearing lead weight* on your feel when you run; you It wonder why the examiner as sending so slowly!

Code Tapes

Courageous S6.95__

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