MIL-PRF-26542/12C
Performance:
Sensitivity at ground level: 34.96 dB 40.98 dB (re 1 µV) or 55.97 µV 111.94 µV with an SPL input
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of 2.8 Pascal's (28 dynes/cm ) at 1 kHz.
Sensitivity at altitude: At a simulated altitude of 25,000 feet, the sensitivity shall be equal or not more
than 8 dB of the ground level sensitivity.
Frequency response: The frequency response at ground level shall be within the limits shown on
figure 2. The frequency response at 25,000 feet shall be within the limits shown on figure 3. The
frequency response range shall be 200-6,000 Hz. The response curves generated shall be on the
same scale as shown in figures 2 and 3. The response curve shall not exceed the upper and lower
limit curves of the stationary Frequency Response Envelope, within the frequency ranges identified in
the appropriate chart (see figures 2 and 3).
Impedance: Four (4.0) ohms to 6.0 ohms. The impedance at any frequency over the range of 200
Hz to 6,000 Hz shall not deviate from the 1,000 Hz impedance by more than 20 percent.
Resistive load: 5.0 ohms.
Dielectric withstanding voltage: This test may be performed on the bracket in isolation from the
microphone element, at the option of the manufacturer.
Microphone bracket leakage: There shall be no more than 100 milliliters/minute of leakage, and the
test shall only be performed at 60,000 feet simulated altitude. This test shall be performed at a
laboratory acceptable to the Qualifying Activity.
Intended use: Microphone element M-169A/AIC is a noise canceling dynamic moving coil
microphone element designed for use in an oxygen mask or pressure-type oxygen helmet, at
altitudes where the use of an oxygen helmet is required. The microphone element is intended for use
with both the MBU-12 and MBU-20/P (Combat Edge) oxygen masks, to provide communication under
the noise conditions encountered in military aircraft.
The microphone assembly shall be identified as shown in table I and tested in accordance with the tests
listed in table II.
TABLE I. Part or Identifying Number (PIN) designations.
PIN
Characteristics
M-169A/AIC
Microphone assembly, as shown in figure 1.
M26542/12-01
Pass-through connector, alone.
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