Radio Flea Market, 2m FM, and Other Ham Radio News

This installment of a regular feature covers the use of 2m FM equipment, a get-together the author and several ham radio enthusiasts had at a radio flea market in New Hampshire, and the use of solar cells in ham radio operation.

| September/October 1981

Copthorne Macdonald is the inventor of slow-scan television, a method of amateur radio transmission that allows ham radio operators to both hear and see each other during shortwave broadcasts.  

Radio Flea Market

Last May I had an opportunity to meet some of the eastern NDR folks, and doing so proved to be a real treat! For the past several years, you see, Bob Robinson (K1PRR) has attended the Deerfield Hamfest—a giant radio flea market held each May in Deerfield, New Hampshire—and he thought that the event would be a good place to rendezvous. Six of us made it there: Lee Branum (KL71JG), Greg Bluhm (N1BHQ), Cy Currier (KITES), and Tim McEntee (WD4KN0), in addition to Bob and me. The festival was made even better for me by the excitement of seeing old friends whom I'd never met, which is one of the paradoxical experiences ham radio makes possible! I'm already looking forward to next year's hamfest.

2-Meter FM: The Details

In the last NDR column, Jerry Rosman (KA7FTN) told us how mountaintop radio relay stations provide a communications lifeline linking his remote homestead with the outside world. Jerry's experience is by no means unusual, either. In fact, VHF communication via repeaters has become the mode of choice for "telephone quality" conversations at distances of up to 100 miles. Here's how it works:

Ham operators with 2-meter FM equipment commonly use either 1- to 3-watt hand-held transceivers or 1- to 10-watt mobile units. Direct communication from rig to rig is possible, but the broadcasting range is only a few miles, even in average terrain. However, when the low-power transceivers communicate indirectly—through an intermediary known as a repeater—a truly useful system comes into being. To understand how it works, think of a repeater as a receiver connected to a transmitter: It listens on one frequency and then automatically retransmits whatever it hears on a different wavelength.

The communication leverage provided by such relay stations is due primarily to their extremely favorable locations ...and, as you can likely imagine, 2-meter FM'ers always seem to be on the lookout for good repeater sites. Hams who work for TV stations have, in many instances, obtained permission to put their repeaters high on the stations' antenna towers. In other cases, members of radio clubs have chipped in to rent space and power from commercial microwave operators with desirable mountaintop locations.

The beauty of this system is that all hams able to communicate with the repeater are also able to communicate with one another! It's quite possible, for instance, for two operators who are 50 miles apart to chat with perfect clarity, using only low-power walkie-talkies, with the help of a well-situated repeater. And if you use a more powerful transceiver connected to a directional beam antenna, as Jerry does, distances of 200 miles or more can sometimes be spanned!

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