AUX muting by external contact closure for push-to-talk microphones. TEL input for telephone paging applications. TEL input voice-activated (VOX) mute over AUX input. Variable threshold for TEL input voice-activated AUX mute. Audio output for tape recorder or booster amplifier. Outputs for 4-ohm (direct), and 16-ohm, 25V and 70V speaker s
