commgrp@silver.bacs.indiana.edu (05/20/88)
I'm looking for literature about avalanche beacons, especially schematics. I am also looking for a source of inexpensive units. Skiers carry tiny transmitters which help rescuers locate them quickly if they are buried by an avalanche. The beacons are cigarette-pack sized, and operate at 2275 Hz (yes, Hz) and/or 475 kHz. (There is no technical reason for the dual frequency used by the most expensive units; the Swiss and Austrians were unable to agree on a standard.) Avalanches are very rare here in Indiana. I have borrowed a pair of 2275-Hz beacon transceivers to evaluate them as "cave radios" used for finding the surface location above an underground transmitter, and measuring depth (reference: _73_ magazine, Feb. 1984 p. 42). I have extended their normal 100-foot range to over 300 feet simply by placing the unmodified units within large (20-30" dia.) resonant coils of several hundred turns of wire. I plan further experiments which should extend their range even more. The beacons are sealed, so I cannot inspect their insides. They apparently have ferrite loopstick antennas. Background atmospheric noise indicates that the receivers are very sensitive. The units are made by Alpine Research, Inc., of Golden, Colorado. Any information or references will be appreciated. Thanks in advance; e-mail replies don't always go. -- Frank Reid W9MKV PO Box 5283 Bloomington, IN 47402-5283 (812) 335-0711 w reid@gold.bacs.indiana.edu bitnet: reid@iubacs "Ski Indiana! Surf Ohio!"