MIL-PRF-26542/9C
REQUIREMENTS:
Component parts:
Microphone element: Shall be in accordance with figures 1 and 2, as specified by the PIN (see table I).
Bracket: Shall be in accordance with figure 1, for interface to the dimensions of the gas mask assembly. Two
(2) screws securing the bracket to the microphone element, Air Force-Navy Aeronautical Standard type
AN500D-6 (3/8 inch) 2-56 thread, shall be supplied for interchangeability. The bracket shall also be supplied
with suitable hardware to ensure that the microphone element does not become disengaged during normal use,
such as lock washers.
Cable assembly: Shall be PIN M22442/36-5, for interchangeability, and to meet the environmental requirements
of this specification and the end-item-assembly.
Plug assembly: U-173/U, in accordance with USAF Drawing 57B12662, or electrically and mechanically
compatible part meeting the environmental requirements of MIL-PRF-26542.
Performance:
Sensitivity at ground level: 36.90 dB - 42.92 dB (re 1 µV) or 69.98 µV 139.63 µV with a SPL input of 28
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dynes/cm at 1 kHz.
Sensitivity at a simulated altitude: Sensitivity shall be within 8 dB of the ground level sensitivity when tested at
25,000 feet.
Frequency response at ground level and at 25,000 feet: The envelope shall be as shown on figures 3 and 4.
The frequency response range of the element shall be 200 Hz to 5,000 Hz.
The response curves generated shall be on the same scale as shown on figures 3 and 4. 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 charts (see figures 3 and 4).
Impedance: 4.0 ohms to 6.0 ohms.
Resistive load: 5.0 ohms.
Intended use: Microphone element M-101/AIC is a noise canceling dynamic moving coil microphone element
designed for use on a headband type headset at low altitudes or 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 primarily in US Army applications requiring the M45 or the M40A1 series of gas masks, to provide
communication under the noise conditions encountered in military aircraft.
TABLE I. PIN designations.
PIN
Characteristics
M26542/9-01
Supplied with the bracket and cable assembly
M22442/36-5 (19.50 in), as shown on figure 1.
M-133/U
Supplied with microphone element only
The microphone assembly shall be tested in accordance with the tests listed in table II.
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