$5 INCLUDING: July/August 2004 Forum for Communications Experimenters Issue No. 225 A Low-Cost, PC-Based Network Analyzer The national association for ARRL AMATEUR RADIO 225 Main Street Newington, CT USA 06111-1494 2004 QEX 7 Cover.pmd 1 5/11/2004, 3:04 PM APRS—Moving Hams on Radio ARRL’s Low Power Communication ARRL’s HF Digital Handbook and the Internet —2nd edition —3rd edition A Guide to the Automatic Position The Art and Science of QRP. Build, experiment, Learn how to use many of the digital Reporting System. operate and enjoy ham radio on a shoestring budget. modes to talk to the world; PSK31, RTTY ARRL Order No. 9167—$17.95 plus s&h ARRL Order No. 9175—$19.95 plus s&h PACTOR, Q15X25 and more! ARRL Order No. 9159—$19.95 plus s&h VoIP: Internet Linking for The ARRL Operating Manual ARRL’s Vintage Radio Radio Amateurs —8th edition QST articles about the lure of vintage A guide to some of the popular VoIP The most complete book about Amateur Radio Amateur Radio gear. Includes classic ads! systems used by hams: EchoLink, IRLP, eQSO and WIRES-II. operating. Everything for the active ham! ARRL Order No. 9183—$19.95 plus s&h ARRL Order No. 9132—$25 plus s&h ARRL Order No. 9264—$17.95 plus s&h The national association for 2003 ARRL Periodicals on CD-ROM ARRL AMATEUR RADIO Includes QST, NCJ and QEX magazines. SHOP DIRECT or call for a dealer near you. View, search and print! ONLINE WWW.ARRL.ORG/SHOP ARRL Order No. 9124—$19.95 plus s&h ORDER TOLL-FREE 888/277-5289 (US) Shipping and Handling charges apply. Sales Tax is required for orders shipped to CA, CT, VA, and Canada. Prices and product availability are subject to change without notice. QEX 7/2004 QS5 2004 New Pubs Ad.pmd 1 5/14/2004, 10:18 AM About the Cover Tom McDermott, N5EG and INCLUDING: Karl Ireland describe an easy to build, professional quality vector network analyzer that makes use of your PC for QEX (ISSN: 0886-8093) is published bimonthly in January, March, May, July, September, and processing and display. November by the American Radio Relay League, 225 Main Street, Newington CT 06111-1494. Periodicals postage paid at Hartford, CT and at additional mailing offices. POSTMASTER: Send address changes to: QEX, 225 Main St, Newington, CT 06111-1494 Issue No 225 Mark J. Wilson, K1RO Publisher Doug Smith, KF6DX Editor Features Robert Schetgen, KU7G Managing Editor Lori Weinberg, KB1EIB 3 A Low-Cost 100 MHz Vector Network Analyzer with Assistant Editor USB Interface L. B. Cebik, W4RNL Zack Lau, W1VT By Tom McDermott, N5EG, and Karl Ireland Ray Mack, WD5IFS Contributing Editors 15 Crystal Filters with Variable Bandwidth and Constant Production Department Center Frequency Steve Ford, WB8IMY Publications Manager By Robert Lytle, N3FT Michelle Bloom, WB1ENT Production Supervisor 18 Help for Amplifier Failure in the HP8640B Sue Fagan Graphic Design Supervisor By Markus Hansen, VE7CA Mike Daniels Technical Illustrator 23 A Doubly Balanced “H-mode” Mixer for HF Joe Shea By Sergio Cartoceti, IK4AUY Production Assistant Advertising Information Contact: 33 Improved Remote Antenna Impedance Measurement Joe Bottiglieri, AA1GW, Account Manager 860-594-0329 direct By Ron Barker, G4JNH, VK3INH, ex VK2INH 860-594-0200 ARRL 860-594-4285 fax 43 A Tutorial Dispelling Certain Misconceptions Circulation Department Concerning Wave Interference in Impedance Matching Kathy Capodicasa, Circulation Manager Cathy Stepina, QEX Circulation By Walter Maxwell, W2DU, ARRL Technical Advisor Offices 225 Main St, Newington, CT 06111-1494 USA 51 Resistance—The Real Story Telephone: 860-594-0200 Telex: 650215-5052 MCI By Doug Smith, KF6DX Fax: 860-594-0259 (24 hour direct line) e-mail: [email protected] Subscription rate for 6 issues: In the US: ARRL Member $24, Columns nonmember $36; US by First Class Mail: ARRL member $37, nonmember $49; 54 Book Reviews 61 Letters to the Editor Elsewhere by Surface Mail (4-8 week delivery): ARRL member $31, nonmember $43; 55 Antenna Options 62 Next issue in QEX Canada by Airmail: ARRL member $40, By L. B. Cebik, W4RNL nonmember $52; Elsewhere by Airmail: ARRL member $59, 60 Tech Notes nonmember $71. Members are asked to include their membership control number or a label from their QST when applying. In order to ensure prompt delivery, we ask that Jul/Aug 2004 QEX Advertising Index you periodically check the address information on your mailing label. If you find any inaccura- cies, please contact the Circulation Department American Radio Relay League: Cov II, National RF: 64 immediately. Thank you for your assistance. 53, Cov III, Cov IV Nemal Electronics International, Inc.: 63 ARA West: 64 Noble Publishing Corp.: 63 Copyright ©2004 by the American Radio Relay League Inc. For permission to quote or reprint ARRL/TAPR DCC: 17 SSB Electronic: 54 material from QEX or any ARRL publication, send Atomic Time, Inc.: 64 Teri Software: 32 a written request including the issue date (or book Down East Microwave, Inc.: 63 Tucson Amateur Packet Radio Corp.: 62 title), article, page numbers and a description of JWM Engineering Group: 63 Watts Unlimited: 22 where you intend to use the reprinted material. Send the request to the office of the Publications Lewallen, Roy, W7EL: 64 Manager ([email protected]) Jul/Aug 2004 1 table of contents.pmd 1 6/4/2004, 2:50 PM THE AMERICAN RADIO RELAY LEAGUE Empirical Outlook 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 Behind the Scenes at QEX the establishment of networks to provide broadband-over-power-lines (BPL) communications in the event of disasters or other Here are a few notes about our staff struggle. Additionally, Ray is our emergencies, for the advancement of radio art and how we operate. In light of some regular proofreader. Even as we adapt and of the public welfare, for the representation to change, the good news is that we of the radio amateur in legislative matters, and recent changes, now seems a good time for the maintenance of fraternalism and a high to elaborate. are adding to our capacity to bring you standard of conduct. Theorem: In almost any office setting, the best in communications experi- ARRL is an incorporated association without there is always one person who knows mentation. capital stock chartered under the laws of the I think you will agree that all those state of Connecticut, and is an exempt organiza- everything that goes on. Assistant Edi- tion under Section 501(c)(3) of the Internal tor Lori (Maty) Weinberg, KB1EIB, is individuals deserve hearty congratu- Revenue Code of 1986. Its affairs are governed that person for us. She logs and ac- lations for their central roles in mak- by a Board of Directors, whose voting members ing League publications topmost in are elected every two years by the general knowledges submissions and distributes membership. The officers are elected or them amongst our editorial board, their field. Mentioned too infrequently appointed by the Directors. The League is which consists of our editorial staff plus is that ARRL’s efforts—and yours— in noncommercial, and no one who could gain ARRL Technical Advisors. She sends the publishing world have augmented financially from the shaping of its affairs is our collective standing in a unique eligible for membership on its Board. out post-production page proofs and “Of, by, and for the radio amateur, ”ARRL handles author release forms, as well as way. Keep those projects going! numbers within its ranks the vast majority of much of our other correspondence. active amateurs in the nation and has a proud My own job is to ensure the best In This Issue history of achievement as the standard-bearer in amateur affairs. content. That means not only deter- Tom McDermott, N5EG, and Karl A bona fide interest in Amateur Radio is the mining what goes into each issue but Ireland present their 100-MHz vector only essential qualification of membership; an also reviewing page proofs, conduct- network analyzer design. If you build Amateur Radio license is not a prerequisite, it, this instrument will bring you ca- although full voting membership is granted only ing correspondence, assembling a let- to licensed amateurs in the US. ters column, writing this editorial pabilities that might otherwise be be- Membership inquiries and general corres- and so on. You intrepid writers have yond your means. pondence should be addressed to the made my job easier by largely remov- Rob Lytle, N3FT, introduces an im- administrative headquarters at 225 Main Street, Newington, CT 06111 USA. ing worries about having enough good provement to the so-called Jones filter. material to fill these pages. I do some It allows the center frequency of a vari- Telephone: 860-594-0200 of the copy editing before handing ar- able-bandwidth crystal filter to remain Telex: 650215-5052 MCI ticles to our Managing Editor for fur- reasonably constant as the bandwidth is MCIMAIL (electronic mail system) ID: 215-5052 FAX: 860-594-0259 (24-hour direct line) ther processing. Every now and then, changed. Using readily available com- I get to write an article. ponents, Markus Hansen, VE7CA, Officers Managing Editor Bob Schetgen, shows how to fix your HP8640B when President: JIM D. HAYNIE, W5JBP KU7G, is at the center of the QEX its output pre-amplifier fails. We under- 3226 Newcastle Dr, Dallas, TX 75220-1640 work storm. He assigns final format- stand that is a fairly common situation Executive Vice President: DAVID SUMNER, ting to text and graphics and leads ar- with the generator.