Telex Airman 750, Руководство по техническому обслуживанию и ремонту

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CHAPTER 4
Maintenance
4.1 Microphone Validation and Adjustment
4.1.1 Microphone/Amplifier Sensitivity Check
Headset specifications are designed to comply with FAA TSO C-57a, C-58a, including
RTCA DO-170 & DO-160A.
To test the sensitivity of the microphone , do the following:
1. Construct a test circuit . For more information, see Figure 1.
2. Connect the test circuit to the microphone plug of the headset. For more information,
see
FIGURE 1.
Airman 750 Headset Boom Microphone Sensitivity Check Test Circuit
“Airman 750/760 Models and Connector” on page 8.
3. Calibrate a lab microphone .
4. Place the calibrated lab microphone 1/4 inch (6mm) above an artificial mouth (Bruel
and Kjaer type 4219).
5. Connect a signal generator to the artificial mouth.
6. Adjust for an output 100 dBspl or of 114 dBspl @ 1/4 inch from the opening to the lab
microphone.
7. Remove the lab microphone .
8. Position the headset boom microphone 1/4-inch (6mm) above the output of the
artificial mouth.
NOTE:
The acoustic hole in the boom mic should be aligned with the center of the artificial
mouth opening. Windscreens should be removed for this test.