Winter 2009 Issue

Homing In

Transmitter Hunters Track Rockets in the Desert and Plan to Meet in Boston

By Joe Moell,  KØOV

Surrounded by their high-power rockets, Mark Melnyk (left) and Rob Foth, KE6YGF, carefully prepare seals that hold the solid fuel sticks in place. (Photo by Joe Moell, KØOV)

Six months before I got my first ham radio license, I tuned my little Hallicrafters S-38D receiver to 20 MHz and heard the faint beep-beep signals that ushered in the space age. I was fascinated by rockets such as the one that put Sputnik into orbit, how they were propelled and how they were guided.

For me and for many others, that fascination continues into the 21st century. Tens of thousands have built and launched their own rockets, big and small, with help from organizations such as the National Association of Rocketry (NAR).1 As it has gained in popularity, rocketry has become safer. The days of metal shells and mixed liquid propellants have given way to cardboard, plastic, fiberglass, and carbon-fiber frames with solid fuel sticks that can be purchased at hobby stores.

Serious “model rocketry” enthusiasts usually progress quickly into “high power rocketry” with motors that are too powerful to be purchased in shops. They don’t achieve orbit, of course, but the really big ones can experience over 30 G’s on liftoff, fly at super-sonic speeds, top out at heights of 15,000 feet or more, and parachute down several miles from the launch site. Since they aren’t inexpensive, builders want to retrieve them. That’s where amateur radio and transmitter hunting enter the picture.

I’m Over Here

Some hobbyists outfit their craft with sound sources that activate on impact and beep loudly. Everybody possesses direction-finding equipment for audio, but range is limited to several hundred feet, and less if the wind is blowing strongly. Since anyone nearby can hear the beacon, rocket-napping isn’t unheard of.

Over the years, a few companies have offered radio tracking systems using unlicensed transmitters on the 88–108 MHz FM broadcast band. However, the range of a Part 15 compliant transmitter on those frequencies is quite limited, especially in locations where the band is full of mountaintop transmitters running tens of kilowatts of effective radiated power. Licensed hams have much better alternatives. They can build their own mini-transmitters or buy them ready-to-use in the uncrowded 222- and 433-MHz bands.
 

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