PT \(see 6.1 and 6.4\).

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'INCH�POUND' by harrysmeltzer - Page 10 of 13

MIL-DTL-11134G

4.6.1 Test equipment and procedures. Except as otherwise specified herein, test equipment and procedures shall

conform to IEEE 258 and ANSI S3.7.

a. The secondary sound pressure reference standard shall be Type L (not N or H) pressure microphone

conforming to ANSI S1.12 and calibrated in accordance with ANSI S1.10.

b. The distance from the face of the microphone to the plane of the opening of the artificial voice shall be 0.25

inch. The voltage across the voice coil of the artificial voice shall be calibrated to provide a sound pressure

level of 2.8 Pascals in the frequency range of 300 to 4,000 Hz.

c. In the test circuit on figure 2 of IEEE 258, RL is 40 ohms non-inductive, C is 100 microfarad, Ebb is 24 volts

dc and the variable resistor is 250 ohms.

d. The sound pressure level of 2.8 Pa (103 dB) shall be used in place of the 94 dB specified in IEEE 258.

e. Microphone and earphone tests 4.6.2.3 and 4.6.2.4 shall be performed on the elements only. All other

tests shall be performed with the elements installed in the handset. Measurements shall be made at the

connector U-161/U terminals.

f. Continuous trace response data are required for the microphone element.

4.6.2 Methods of inspection.

4.6.2.1 Insulation resistance. The assembly shall be tested in accordance with method 302, test condition B, of

MIL-STD-202 to meet the requirements of 3.5.1. There shall be no evidence of arcing or insulation breakdown during

the test.

4.6.2.2 Operation. Establish a test circuit by providing a battery bias supply between connector pins E and C,

connect pin C to pin B through a 100 mf capacitor, and connect pin D to pin F and pin H to pin A. Speak into the

microphone. Side-tone shall be heard in the earphone only when the push-to-talk switch is depressed (see 3.5.2).

4.6.2.3 Microphone.

4.6.2.3.1 Response. (see 3.5.3.2)

a. Perform the power response test of the microphone in the vertical position with a bias current of 85 ma dc

and determine compliance with 3.5.3.2 a.

b. Perform the power response test of the microphone as specified in 4.6.2.3.l a above, with the microphone

rotated in a vertical plane +90, -90, +45 and -45 degrees and determine compliance with 3.5.3.2 b.

c. Perform the power response test of the microphone as specified in 4.6.2.3.l a above, with the bias supply of

the battery and variable resistor replaced with a bias battery of 1.5 volts dc and determine compliance with

4.6.2.3.2 Impedance. Using the test circuit of 4.6.2.3.l a, 1,000 Hz, measure the voltage (dc) across the

microphone and the direct current flowing through it and determine that their ratio complies with 3.5.3.3.

4.6.2.3.3 Unagitated current. The microphone under test shall not be preconditioned (agitated) prior to this test.

Use the test circuit as in 4.6.2.3.l a, except that the bias voltage and variable resistor combination shall be replaced

with a bias battery of 6 volts dc and the load resistor reduced to 30 ohms. During a 10 minute period, measure the

peak current flowing through the microphone for compliance with 3.5.3.4.

4.6.2.3.4 Carbon noise. Using the test circuit as in 4.6.2.3.l a, except that the bias current shall be adjusted to 170

milliampere dc and the sound pressure level shall be 7.0 Pa, perform the test in accordance with the IEEE 258 and

determine compliance with 3.5.3.5.