A PIC-Based Repeater Controller

GB3GD is controlled by a custom-built module designed by GD4HOZ.

The design was originally created for the GB3LD repeater operated by the South Lakeland Repeater Group. Since its creation, it has found a home in a number of repeater sites around Britain.


  • CTCSS TX tone generation.
  • CTCSS RX Tone Detection.
  • DTMF remote control of various parameters.
  • 1750Hz tone detection.
  • In-Band tone generation (CW, cue beeps etc).
  • Talkthrough audio gating.
  • Raynet (Carrier access) mode.
  • Internet Linking Mode.
  • Various test modes.

And all in the space of 3 (Yes, three) IC's.

The heart of the system is a PIC16F74 microcontroller. More recent designs have been built on the 16F877 which is pin abd code compatible.

Peripheral to this are a DTMF decoder and a CML FX828 CTCSS/Selcall CODEC. Status information is provided on an intelligent LCD module

This design makes the FX828 do things for which it was never intended, but it does them rather well.

Above, the controller, built on stripboard, installed in the F494 which we used for GB3GD before moving to the FX5000.

Below, left, A more detailed view of the board.

Below, right, a newer version built-up on a PCB and installed in GB3IM's PRF1060 duplexer bay.

For the benefit of any amateur wishing to use this design, I have placed the entire project in the public domain. The schematics and source code are freely available for amateur use.

There is a Yahoo! discussion group where other users of this design have posted ideas and information, and where you can find the circuit and software details.

Go to top
JSN Boot template designed by JoomlaShine.com