The following transceiver wiring diagram applies for XCOM VHF760 models. Here you will find detail illustration and pinouts diagram of the XCOM VHF760, i.e. Pin 1 for Electret Amplified Dynamic Pilot Mike, Pin 2 Music Aux Audio Input, Pin 3 Electret, Amplified Dynamic Co Pilot Mike, Pin 4 Speaker Output 8-16 Ohms, Pin 4 Intercom ON ground to operate, etc. Note that when using Electret or Amplified Dynamics you must use individual inputs (1 and 3). Do not parallel more than one per input; Speaker now has a separate negative lead – do not ground the speaker as damage will result in the radio speaker amplifier; and 22,000 uF 25V Electrolytic Capacitor Must Be Installed. (Source: xcom760.com).