The above Astatic handbook doesn't cover the Cam 88 and unlike other Cobra models, finding a schematic on the Cam 88 is difficult, at least on-line. I would first figure out the pin-out of that old 60’s style 4 pin Amphenol jack. I would either buy Sam’s Photofact # 9 or I would take apart the stock mic or plug to determine those connections. Usually with radios this old, only 3 pins will be used, audio, transmit and ground. You probably won’t need to consider any “receive” wire connection. The relay inside the radio will be handling that part. As a side note, some people like to keep the old jack to preserve originality on these old radios Others prefer to change that jack over to the modern 4 pin. That way you can easily swap out any number of mics that use the standard Cobra 4 pin configuration.