Batboard

I am using this quantar as a base station to talk to a local repeater. The only problem I am having is that the receiver does not mute. I have the quantar set as a base, not a repeater, but the receiver stays on when the PTT is pressed. The mic is a HMN1001B connected into the port on the front panel of the SC. I am using two antennas at the moment. The TX is on the roof and the RX inside the building, it picks up the repeater just fine.

I have studied the RSS book and I can't find the setting that would mute the receiver in TX. I can't find anything in the hardware book that explains how the mute works in this radio. Would appreciate any help on this.

Thanks