Check the listing for details. Heathkit GC-1000 Tone Board Extender. Condition: New. Listed at 50.00 USD. Heathkit GC-1000 Tone Board Extender These are some GC-1000 Tone Board Extenders that we had made. When working on the tone decoders, it is very difficult to get to the parts on the board to troubleshoot. This board will mount where the tone board was and allow you get the tone board up and out of the way of the rest of the GC-1000 so you can use your scope / meter or whatever to troubleshoot the board. In addition, we also added a few convenient test points: Vcc, Ground, Audio In, 100 Hz decode output, and the 1000 Hz decode output. I have found the best way to align these is to generate a 1000 Hz tone to your RF generator, feed the RF into the Antenna input on the GC-1000 then reduce the RF level as you adjust the 100 and 1000 Hz Adj pots. You can really zero in on the correct adjustment for each. The 'Audio' test point can also be used for Audio out or Audio in to the tone board if you remove the RF board. The board can be mounted in the GC-1000 with the original tone board screws, or just left installed without the screws. The missing male pin is for the index of the tone board. It is NOT broken... These are brand new boards. International sales only through the eBay Global Shipping Program