The TMN1004B Desk Microphone contains a microphone and preamplifier circuit board, and a dual-action "Transmit" switch which allows easy operation for either hand-held or desktop use in carrier squelch applications. The TMN1005B Desk Microphone is the same as the TMN1004B except that it contains an additional dual action "Monitor" switch for use in coded squelch applications.
Before connecting the desk microphone to external equipment, verify that printed circuit board jumpers JU1 and JU2 are configured correctly for the system application. Microphones are shipped from the factory with both jumpers installed. The jumpers are removed to obtain the following conditions:
Jumper JU1 is removed when parallel microphones or other local equipment are connected at the same microphone input.
Jumper JU2 (Model TMN1005B only) is removed when it is necessary to prevent an operator from transmitting without first monitoring a channel to verify it is clear. With JU2 removed, both the MONITOR and TRANSMIT switches must be activated before transmitting.
The desk microphone is connected to external equipment through a 7-foot stranded cord. The pinout of the cable is as follows:
|Yellow*||Speaker Audio Hot|
|Red*||Speaker Audio Mute|
*Used only when transmit monitor is desired at parallel-connected dispatch points when microphone is transmitting.
The schematic for the microphone can be found here.