Batboard

I need to have a lead go to ground on a P200 lowband when it receives a signal WITH the correct DPL code. Anyone ever do this? I can run a cable into the radio, as this is a "junk" radio (bad XMT) that's just going to be used for a specific function with receive.

I take it you are using the P200 as a remote reciever. I've taken older MT500 with PL/DPL and made cross banders out of them. If you know your switching transistor theory, you can take just about any decoder and find the poiint on the decoder board that switched "on" the audio power amp. Quite simply, I like to find that point, whether it is switching ground(stanby) to 5-7.5 volts on rx, or vice versa, run that through the fathful 2N2222 transistor, and have it turn on a relay. What happens if connect your audio output straight to the detector, you may have constant open squelch when transmitting on the host radio. I use a double pole, double throw relay for that apllication. It hasn't failed me yet. Have one working for a fire dept. now for 7 years.
Try that out.
Jimbo