Batboard

Does anyone have a cheap way to convert A logic Low into a chasis ground so I can turn a repeater on/off with a st809 dtmf decoder I am trying to wire this to a r1225 to enable and disable the repater over the air any suggestions

I don't know how your knowledge of electronics is, but I'll give a brief answer, if need be someone can fill in more details.
P
robably a couple of transistors would do it, an NPN with the emitter to ground, collector to whatever you're trying to pull to ground, then to get it to turn on with a logic low you'd drive the base with a PNP transistor as an inverter.
Cost wise probably under a dollar.

There's an INPUT pin option in the RSS, accessory pins for repeater disable.