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PRM80 Wide-Narrow Deviation Mo

This mod came about as I use a commercial narrow band frequency for work, and wish to have amateur frequencies to use as well.

Program one of the function buttons to activate the AUX function in the RSS. Under the deviation adjustment pot on the control board there is 2 vacant pads which connect across the deviation adjustment. Make the circuit in the following link. Also see the photo which shows where to get the aux output from the microprocessor.

The parts required are

  • 1Meg ohm resistor
  • 38k ohm resistor
  • BC558 Transistor.

I have mounted the components on the circuit board with hot glue and connected them “ugly” style. I found with a correct narrow deviation adjustment adding a 38k resistor gave me a wide band setting. you can replace this with a 50k pot if you require.

The radio is in narrow “mode” when the AUX indicator is off.

Circuit Schematic Aux Pin

prm80_wide_nar_dev_mod.txt · Last modified: 2018/09/14 23:17 by vk3smb