I am using an FM1200 as a 4m internet gateway and have just built a new interface to link the radio to the computer. This interface has a PIC chip to control all the switching instead of relying on just VOX audio and also has a built in DTMF decoder.
This has presented me with a problem as I need to obtain a +5v ( COR signal ) from the radio when the squelch opens in order to trigger the interface switching. The interface will also work with reverse switching, in other words the +5v can be present when idle and drop to zero when the squelch opens. I have tried using the gate that operates the green LED on the display unit but this only seems to switch the ground side of the LED
Anyone know where else I can look in order to pick up a squelch switched 5v ?