2m Amateur Radio Fox

2m (146.55 MHz) Amateur Radio Fox (hidden transmitter)

The is a fox that the local radio club is using for transmitter hunting practice. The theory behind this circuit is that the oscillator is a programmed oscillator with a frequency of 146.55 MHz. The good thing about the programmable oscillator is that they are not always very stable. The phase noise is a good thing for this transmitter. I am using an astable multivibrator operating at approximately 1k Hz. When the oscillator is enabled and disabled it does not start back up in phase. This allows you to hear the tone on an FM receiver. You will have to turn the squelch all the way down on your radio so you can hear the tone. This transmitter actually sounds better on an AM receiver.

Schematic for the fox. (Click on the image for a larger one)

The fox now installed in the Altoids tin.

The outside view of the fox not that it is now painted so that it is easier to hide outside.