October QEX Advertising Index

QEX (ISSN: 0886-8093 USPS 011-424) is published monthly by the American Radio Relay League, Newington, CT USA.

Second-class postage paid at Hartford,

Connecticut and additional mailing offices.

David Sumner, K1ZZ

Publisher

Jon Bloom, KE3Z

Editor

Lori Weinberg Assistant Editor Harold Price, NK6K Zack Lau, KH6CP Contributing Editors

Production Department

Mark J. Wilson, AA2Z Publications Manager Michelle Bloom, WB1ENT Production Supervisor Sue Fagan

Graphic Design Supervisor

Joe Costa Technical Illustrator

Joe Shea

Production Assistant Advertising Information Contact:

Brad Thomas, KC1EX, Advertising Manager American Radio Relay League 203-667-2494 direct 203-666-1541 ARRL 203-665-7531 fax

Circulation Department

Debra Jahnke, Manager

Kathy Fay, N1GZO, Deputy Manager

Cathy Stepina, QEX Circulation

Offices

225 Main St, Newington, CT 06111-1494 USA

Telephone: 203-666-1541 Telex: 650215-5052 MCI FAX: 203-665-7531 (24 hour direct line) Electronic Mail: MCIMAILID: 215-5052 lnternet:[email protected]

Subscription rate for 12 issues:

In the US: ARRL Member $12, nonmember $24;

US, Canada and Mexico by First Class Mail:

ARRL Member $25, nonmember $37;

Elsewhere by Airmail:

ARRL Member $48, nonmember $60.

QEX subscription orders, changes of address, and reports of missing or damaged copies may be marked: QEX Circulation. Postmaster: Form 3579 requested. Send change of address to: American Radio Relay League, 225 Main St, Newington, CT 06111 -1494.

Members are asked to include their membership control number or a label from their QST wrapper when applying.

Copyright © 1994 by the American Radio Relay League Inc. Material may be excerpted from QEX without prior permission provided that the original contributor is credited, and QEX is identified as the source.

American Radio Relay League: Cov III Communications Specialists

Inc: Cov III Down East Microwave: Cov III LUCAS Radio/Kangaroo Tabor Software: 32

PacComm Packet Radio Systems,

Inc: Cov II Tucson Amateur Packet Radio Corp: 22 Yaesu: Cov IV

Z Domain Technologies, Inc: 29

October 1994 1

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, CT06111 USA.

Telephone: 203-666-1541 Telex: 650215-5052 MCI.

MCIMAIL (electronic mail system) ID: 215-5052 FAX: 203-665-7531 (24-hour direct line)

Officers

President: GEORGE S. WILSON III, W40YI

1649 Griffith Ave, Owensboro, KY 42301

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, CT 06111 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, biack 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

Tooling Up for RF

Previously in this space we have decried the lack of low-cost design and development tools for amateurs. While multi-thousand dollar tools abound, they are hardly accessible to the amateur in the street, so to speak.

Well, cheer up. ARRL has taken the initiative to address this problem in one area: RF circuitry. Working with Compact Software, of Paterson, NJ, ARRL will soon make available ARRL Radio Designer. This Windows program performs linear analysis of circuits. That may at first sound like a description of PSPICE, or MicroCAP, both of which are linear circuit simulation tools available at low cost (in their simpler versions, that is I, but ARRL Radio Designer is different. What makes it different is that it really does RF, although it will do low-frequency circuits, too.

One of the frustrating problems with trying to use SPICE-type simulators at RF is that they don't speak the language. S-parameters, Y-parameters, H-parameters, group delay, reflection coefficient, VSWR, return loss, noise parameters—these are part of the lingua franca of both ARRL Radio Designer and human radio designers.

And ARRL Radio Designer includes capabilities usually found only in high-end programs. Want to optimize your preamp design for noise figure? Let ARRL Radio Designer's optimizer find the best set of input matching circuit components to do the job— than ask it what the resulting input VSWR will be. Want to know if you really need 1% resistors in that critical part of the club-project circuit you've designed? ARRL Radio Designer's statistical processing can tell you how many of the club's copies of the circuit will be unstable if you use 5% components.

There are limitations, of course. As a linear circuit simulator, ARRL Radio Designer can't provide information about distortion products or large-signal operation of circuits. But it can help you design and optimize the linear circuits used in your RF designs. Most of the circuits in a radio system are linear, after all. And, as KA2WEU shows us this month, ARRL Radio Designer can sometimes assist in designing even a large-signal circuit such as an oscillator.

ARRL Radio Designer's reports are available in both graphical and tabular form, as part of its Windows user interface. That means you can see the results on the screen right away, and you can print the resulting graphs or tables of calculated values.

You can read more about ARRL Radio Designer, including some sample applications, in "Introducing ARRL Radio Designer: New Software for RF Circuit Simulation and Analysis," October, 1994, QST.

This Month in QEX

Low phase noise is the holy grail of 1990s radio design. To achieve it, you need to be "Designing Low-Phase-Noise Oscillators." Dr. Ulrich L. Robde, KA2WEU, discusses the design procedure and shows how modern computer circuit simulation tools simplify the problem tremendously.

Part 2 of "Practical Microwave Antennas," by Paul Wade, N1BWT, covers dish antennas—how to build them and feed them.

Need an "Inexpensive PC A-to-D" capability? Gary C. Sutcliffe, W9XT, shows how the PC's game port can serve as a simple way of measuring an external resistance, such as a thermistor.

In this month's "Digital Communications" column, Harold Price, NK6K, expands on his previous discussion of what's holding back amateur packet development.

This month we begin a new column: "Proceedings," As the various amateur technical conferences take place, we will print lists of the papers available in the conference proceedings. Our hope is that this will help you locate those papers that can help you with your experimental efforts.— KE3Z, email: [email protected] (Internet)

2 QEX

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