I have been for the past week or so researching and experimenting with how to use my radio shack scanner and a CDM1250 as a single direction (or RICK) repeater. This is what i have come up with so far (Please let me know if you see any issues or have any other suggestions).
Take the audio out from the scanner and split it (one for the audio to be repeated and another to be used to create carrier). The one audio output to be connected to directly into a RICK repeater cable I had (RA-1M Repeater Adaptor Motorola GM300 CDM CDM1250 RICK - eBay (item 350272827387 end time Dec-25-10 13:38:03 PST)
The audio out from the scanner would be connected to that of what would be coming out of Pin 11 (if I was using a motorola mobile as the source).
The other audio out would be used to create the carrier, or to "key the radio." That output would first go into a voice operated relay switch (Super Sensitive Sound Voice Activated Relay Switch - Assembled
). That would create a 3 amp carrier whenever the scanner produces audio (above a controllable level). However since motorola microphones do not work on carrier, they work on ground, the output from the voice operated relay would have to go into another relay.
From what I have researched motorola mics have a continuous 250ma current through them, when the mic is keyed it grounds thus "keying the mic." To recreate this i have a regulated 250ma transformer (a power supply for a small security camera), that will be connected to another standard relay. The voice operated relay will act a the switch however wired in a fashion to close the relay, thus creating a ground, keying the mic.
When the mic is keyed the audio input is from the scanner thus broadcasting the scanner audio. It is somewhat complex, but i am not aware of any other devices that will repeat audio from your 3.5 mm audio jack.
ALSO, it should be known the frequencies being repeater are all licensed by me (VHF and UHF) and is being repeated over another frequency licensed by me. So there is no legality issues.