The American Radio Relay League

The American Radio Relay League. Inc, is a noncommercial association of radio amateurs, organized for the promotion of interests in Amateur Radio communication and experimentation, for the establishment of networks to provide communications in the event of disasters or other emergencies, for the advancement of radio art and of the public welfare, for the representation of the radio amateur in legislative matters, and for the maintenance of fraternalism and a high standard of conduct.

ARRL is an incorporated association without capital stock chartered under the laws of the state of Connecticut, and is an exempt organization under Section 501 (c)(3) of the Internal Revenue Code of 1986. Its affairs are governed by a Board of Directors, whose voting members are elected every two years by the general membership. The officers are elected or appointed by the Directors. The League is noncommercial, and no one who could gain financially from the shaping of its affairs is eligible for membership on its Board.

"Of, by, and for the radio amateur, "ARRL numbers within its ranks the vast majority of active amateurs in the nation and has a proud history of achievement as the standard-bearer in amateur affairs.

A bona fide interest in Amateur Radio is the only essential qualification of membership; an Amateur Radio license is not a prerequisite, although full voting membership is granted only to licensed amateurs in the US.

Membership inquiries and general correspondence should be addressed to the administrative headquarters at 225 Main Street, Newington, CT 06111 USA.

Telephone: 860-594-0200

Telex: 650215-5052 MCI

MCIMAIL (electronic mail system) ID: 215-5052

FAX: 860-594-0259 (24-hour direct line)



5155 Shadow Estates, San Jose, CA 95135 Executive Vice President: DAVID SUMNER, K1ZZ

Purpose of QEX:

1) provide a medium for the exchange of ideas and information between Amateur Radio experimenters

2) document advanced technical work in the Amateur Radio field

3) support efforts to advance the state of the Amateur Radio art

All correspondence concerning QEX should be addressed to the American Radio Relay League, 225 Main Street, Newington, CT06111 USA Envelopes containing manuscripts and correspondence for publication in QEX should be marked Editor. QEX

Both theoretical and practical technical articles are welcomed. Manuscripts should be typed and doubled spaced. Please use the standard ARRL abbreviations found in recent editions of The ARRL Handbook. Photos should be glossy, black and white positive prints of good definition and contrast, and should be the same size or larger than the size that is to appear in QEX.

Any opinions expressed in QEX are those of the authors, not necessarily those of the editor or the League. While we attempt to ensure that all articles are technically valid, authors are expected to defend their own material Products mentioned in the text are included for your information; no endorsement is implied. The information is believed to be correct, but readers are cautioned to verify availability of the product before sending money to the vendor.

Empirically Speaking

RFI Help from the FCC

Telephone RFI is rapidly becoming the bane of amateur operators. In the past, back when telephones were simpler devices, telephone RFI was fairly uncommon and fixes were pretty easy. Not so today. Every new generation of residential telephones packs more RF-sensitive microelectronics into the case, and competition drives down prices, leading telephone manufacturers to count every penny of production cost. The result is phones that have little if any RFI protection of the circuitry—a recipe for receipt of interference from nearby radio transmitters.

Unfortunately, consumers often assume that if interference occurs, it's the fault of the transmitting station. Last year, the FCC's Compliance and Information Bureau issued a bulletin, CIB-10, to debunk this myth and to provide practical solutions to consumers who are experiencing telephone RFI. This bulletin explains in no uncertain terms that it is the telephone at fault in such cases and provides some simple suggested cures. It also contains a sample complaint letter that the consumer can send to the manufacturer and suggests that if the manufacturer's response is insufficient, the consumer should contact the Electronic Industries Association. A list of providers of RFI filters and RF-proof telephones is also given.

Best of all, the FCC has placed this bulletin on the World Wide Web for easy access. If you are having trouble convincing an irate neighbor that an interference problem has to be resolved at the affected telephone, maybe the "official word" from the FCC will do the trick. CIB-10 is available at http:// WWW/phone.html.

Our Visit to the Pack Rats

We recently had the opportunity to visit the Mt Airy VHF Radio Club (the Pack Rats), which is 40 years old this year, for their "ARRL night" club meeting. This is a vibrant club, full of interesting people doing fascinating things. This month, we are printing some examples of their work. We mention this because one thing that was clear from our visit was that part of the reason for the success of these VHF/UHF/micro-wave experimenters is the synergy provided by the club. All too often, we experimenter types tend to live in the basement workshop, emerging blinking into the sunlight only when dinner calls.

A stack of technical books and magazines is no substitute for dialogue with others interested in your particular corner of radio technology, and the result of the work of a motivated, well-orgapized group can be more than the sum of the efforts of the individual members. For those reasons, we'd like to see more clubs devoted to amateur technical pursuits. Talk it over with the folks jn your area. See if maybe the foundation of a good technical club exists where you are.

Maybe we just all need to get out of the house more!

This Month in QEX

Portable operation usually relies on batteries, and for years, amateurs have used NiCd or lead-acid batteries almost exclusively. Recently, a class of rechargeable alkaline batteries have come onto the market. But are these batteries candidates for use in our applications? The ARRL Lab embarked on a project to find out. In "Testing Rechargeable Alkaline Batteries—and More," Ed Hare, KA1CV, and Mike Gruber, WA1SVF, have the answers. They also give some detail about the test techniques and circuits, providing in the process an interesting behind-the-scenes look at the ARRL Lab in action.

"The Ultimate VFO" would be crystal-stable, able to leap tall buildings in a single bound, uh, that is, able to switch frequencies instantaneously, and cover whatever HF frequency range you need to have it cover. Direct digital synthesis offers a pretty close approximation of these goals, and we've published several such designs of late. Don Kirk, WD8DSB, provides a new design that, controlled by a microcontroller, may answer most all of your VFO needs.

Those slick little DSP boxes that attach to your receiver's output and reduce the noise present in the received audio are amazing. But how do they do that? Doug Hall, KF4KL, explains one method used, "Spectral Subtraction for Eliminating Noise from Speech."

To those unfamiliar with UHF/microwave techniques, they seem pretty arcane. They need not be, though, and amateur experimenters have developed a host of simple ways of building or modifying equipment for the high bands. A small collection of these techniques is contained in "Pack Rat Notes," from the members of the Mt Airy (PA) VHF Radio Club. Check them out; you may find that microwave systems are simpler than you thought.

Finally, "Upcoming Technical Conferences" will bring you up-to-date on the latest scheduled meetings—where the elite meet to greet!—KE3Z, email: [email protected].

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