This document contains proprietary information,
see proprietary statement on first page.
9.5.1.2 Microphone Mode Mic Impedance
When the “MIC_MODE_N” discrete input is grounded, the channel 1 audio input of the
RT-7000 PMR is configured to directly interface with a microphone. The Microphone
Mode Microphone Impedance button in the configuration screen shows the currently
configured microphone impedance. Selecting this button causes a menu of
microphone impedance choices to drop down. Selecting an impedance from this menu
configures the RT-7000 PMR microphone mode audio input.
Choices are 5 ohms, 75 ohms, or 150 ohms.
9.5.1.3 MIC BIAS Setup
To enable Mic Bias on the RT-7000 PMR/RMR the installer will have to complete two
tasks. The first task is to select the 150Ohm option for the Mic 1 Impedance. This will
make the ‘Mic Bias Enabled’ text become highlighted. In addition to selecting the
options shown below, the installer will also need to have Pin 76 on the DB-78
connector brought to ground to enable the MIC MODE. After completing these two
tasks the MIC 1 HI/LO will begin supplying MIC BIAS.
NOTE: Only MIC 1 HI/LO will have BIAS, and the other mic/audio ports will not have
BIAS.
NOTE: The high side of the Mic 1 will have the bias voltage applied. The low side of
the Mic 1 cannot be used for the return path for the bias voltage. The installer must
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