I designed this circuit to enable a Pye PMR MX290 radio that I converted to 145MHz (2m) amateur band to access our UK repeaters. The IC is a divider chip, dividing the 7.168MHz crystal by 4096 equalling 1750Hz. The circuit board fitted into most microphones provided a 7V to 12V dc supply is available. The output can be fed directly to the microphone input connection.
This page was updated on 15th February 2000.