I have been soldering a # 30 wire to pin 13 - goes to +3.1 for PTT → I add a 4.7K resistor to the base of a 2n2222 (grounded emitter) and use the collector for PTT - Let the DSP handle the Squelch and COS / Tone Decode - so only 4 wires - GND, PTT and RX and TX audio - I remove the 3.5 MM Jacks with hot air and add a 56K or 470K resistor (some need more receive signal) and 4.7K in the spkr out (transmit) line - these on ebay worked OK for me - 10PCS CM108 USB Drive Free Sound Card Laptop Computer External Sound Card Module | eBay steve nu5d