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Cheap-n-easy Bunny Beacon

posted Jun 20, 2013, 10:16 AM by Charles Boling
HT w/ earbud from  MP3 player over mic hole
Just in time for a fun Field Day activity...   Need a transmitter for a fox hunt (a/k/a bunny hunt)?  You might already have the components on hand to make quickly and easily, with no need to make custom cables or modify any equipment.

I used Audacity, an open-source sound editor, to make a 20 second MP3 file consisting of a couple of loud chirps, "W7MSH" in Morse code (generated by FLdigi), a voice announcement, and 10 seconds of silence.  Including the silence provides a 50% duty cycle for the transmitter; I decided not to make it transmit 100% of the time, but you certainly could as long as you keep your transmitter power low enough to prevent overheating).

I placed the file on a Sansa Clip audio player (obtained very cheaply several years ago), and set the player for "repeat song" mode.  I tuned the radio, a $40 BaoFeng UV-3R (Mark II) to a simplex frequency and put it on low power (about 1/2 Watt) and activated VOX mode.  I wrapped a rubber band around the radio a couple of times and used it to hold one of the earphones over the microphone hole on the transmitter.

Turn both devices on and start the "music", and place in a plastic bag to keep it from getting wet/dirty.  Presto!  Instant "fox".