Good Afternoon,
Has anyone come up with a simple circuit to tie a repeater controller's port to a PC's serial port for Echolink? I have customized a few Rigblaster type units in the past to add COS funtionality, but the more I have looked at them, the more I think they are a waste of money. A simple circuit consisting of a few parts should be enough to adapt RTS or DTR for a COS signal to the controller, and the controller's PTT to the PC's DSR or DCD input. Most of the commercial interface boxes don't really offer any advantage to the audio paths, so hooking the sound card directly to the controller's audio in/out paths shouldn't be a problem. In the past I've simply tied a radio's COS to the PC's DCD input via an isolation diode and current-limiting resistor with great success, and used the DTR to trigger an NPN transistor across the radio's PTT, but obviously things are reversed on a controller. I was figuring I could use RTS as the controller's COS signal, and set the active hi/lo on the controller accordingly. For the PTT signal, I might need to invert the PTT output of the controller to control DSC or DCD in the right active direction. Anyone have any suggestions or documented circuits before I embark on this project? Eric KE2D
