Operation
7
Microphone Gain Adjustment
The microphone gain has been factory-adjusted to the nominal level required for
normal radio operation and should normally not require adjustment. If needed,
adjustment by a qualified avionics technician is recommended. To access the
microphone gain, insert a small phillips head screwdriver through the access hole in
the headset (see Figure 3) Clockwise rotation increases the microphone gain.
NOTE:
The microphone gain adjustment does not have a stop; at one point the
gain will go abruptly from maximum to minimum and will remain at
minimum gain for approximately 30° of rotation.
Microphone Bias Voltage Requirements
The boom microphone requires a bias voltage of 8-16VDC through 170
Ω
DC
resistance, 150
Ω
AC resistance (per RTCA DO-170). If you are uncertain whether
your avionics equipment meets this requirement, consult the avionics equipment
manufacturer.
FIGURE 3.
Microphone Gain Adjustment
