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ARRL's Technical Information Service Provides Members with Answers

04/29/2009

Have you ever had a technical question that you weren't able to figure out? Even after checking with publications such as The ARRL Handbook or the ARRL Antenna Book, you're still stumped. Have you exhausted every resource you can think of, including your Section's Technical Coordinator (TC)? Just when you think you're at the end of your rope, you remember the ARRL Technical Information Service.

The TIS is staffed by members of the ARRL Lab and is here to provide technical assistance at no cost to ARRL members. Many members seem to be using the service: In a six week period (October 20-November 30, 2008), ARRL Lab staff fielded almost 1300 requests for information from the TIS. These ranged from questions on how to choose the best radio, propagation and BPL to questions concerning antennas, feedlines and towers.

If You Have Questions, the TIS Has Answers

ARRL TCs and Technical Specialists (TS) in the field and at ARRL Headquarters can answer your questions on topics ranging from A (ampere) to Z (impedance) -- and just about anything in between. Our technical staff will help you over the phone, refer you to a volunteer ARRL TS in your area or send you the needed information from a growing collection of information packages. For really difficult questions, an ARRL Lab Engineer will research the League's technical library and send you an answer by postal or electronic mail.

ARRL Lab Engineer Mike Gruber, W1MG, remembers a question that a member sent in recently via e-mail: "I have a 250 foot run of Buryflex 213 from the shack to the switchbox at the top of the tower. I know that results in significant loss at, say, 14 and 17 MHz (I seldom work 10 or 15 and the tower antennas are only for HF), but here is the question: Is it ENOUGH of a loss (for the receiver) to warrant running hardline (it would be free) between the shack and tower switchbox with a tail of about 10 feet of 213 inside the shack, and another tail of about 10 feet at the tower end, running from the switchbox to the TA-33, considering the insertion loss of two additional connectors (to connect the hardline to the 213 on each end) and the impedance difference of the hardline compared with the 213?"

Gruber answered the ham, providing a chart he developed, showing "some losses shown for 250 feet of RG-213 vs half-inch hard line. I selected 50, 100 and 150 ohm resistive loads for this analysis. Any rate, if you consider the case with the highest loss -- 29 MHz with a 150 ohm load -- will only improve by 3.855 - 1.544 = 2.311 dB. If you consider that a typical S-unit is 6 dB, the most dramatic improvement in the example cases I selected is still less than half of an S-Unit. It's not a homerun by any stretch of the imagination. Of course, that extra 2.311 dB may be significant in some cases. If you ran 1500 W, you would only have 881 W at the antenna feed point. The rest would be lost in the feed line."

ARRL Senior Lab Engineer Zack Lau, W1VT, recalls an interesting question he received from a member: "How can I make a simple circularly polarized antenna out of linear elements?" Lau referred him to an article he wrote, "A Simple 10-Meter Satellite Turnstile Antenna," that appeared in the November/December 2001 issue of QEX.

A Wealth of Information at Your Fingertips

The TIS, as one of the many services it offers, maintains a database of more than 2000 suppliers who provide goods and services of interest to radio amateurs. These include manufacturers, dealers, publications, clubs and museums, just to name a few. The TIS also keeps what they call an "expanding list" of technical pages that include articles from QST, QEX and The ARRL Handbook, as well as original articles on a variety of subjects including theory, tutorials and projects. Many pages also contain additional sources for materials and information and Web links of particular interest.

If you need a copy of the QST Product Review from May 1985 that featured the ICOM IC-271A 2 meter multimode transceiver, look no further. The TIS also keeps a list of every QST Product Review published since 1970. ARRL members can also download any QST Product review published after 1980. If you need a quick summary of any HF transceiver featured in a QST Product Review, you can also find it on the TIS Web site.

The TIS also maintains the ARRL Periodicals Archive and Search. This feature provides ARRL members with PDF copies of all QST articles from December 1915 through December 2005, enabling members to view and print their favorite article, project and more. The ARRL Periodicals Archive and Search lists every article for QST from 1915 to the present, QEX from 1981 to the present, Ham Radio from 1968 to 1990 and NCJ from 1973 to the present (please note that beginning in 1998, each issue of QEX covers two months).

"Having access to every issue of QST through 2005 is absolutely incredible!" said ARRL Lab Manager Ed Hare, W1RFI. "The best of the best of QST from every era is now at the fingertips of every ARRL member with a keyboard and an Internet connection. Members can research articles on any subject that interests them, or just browse the past issues. This valuable content will help radio amateurs who use QST as a technical resource -- for projects, equipment 'hints and kinks' -- and for other research contributing to the advancement of the radio art."

For those needing a higher quality reprint, a reprint from QEX or NCJ, or for hams who are not members of the ARRL, the TIS also provides photocopies of articles for a nominal fee. You can reach the TIS via e-mail or by phone at 860-594-0214.

The TIS is just one of the many benefits available to ARRL members. To learn about all the benefits of ARRL membership, including QST, e-mail forwarding service, the outgoing QSL service and more, please visit the ARRL Membership Web page.



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