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 (refer to Figure 4). 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
Gain Adjustment
Figure 4: Microphone Gain Adjustment
MICROPHONE BIAS VOLTAGE REQUIREMENTS
The boom microphone requires a bias voltage of 8-16 VDC through 470Ω DC resistance, 150Ω AC resistance (per RTCA DO-170). If you are uncertain whether your avionics equipment meets this requirement, consult the avionics equipment manufacturer.
