I have a friend who has an old 148/side mic/5 pin. He wants me to wire up a CA73 cobra microphone with a five pin to be a spare mic for his 148. The wires in the mic cord are shield, red. wht and blue. No black! Can this be done? If so please tell me how. I tried to put in a jumper from pin 2 to pin 4 and that didn't work. What else will make it work?