MIL-DTL-11193E
4.4.1 Sampling plan. Accept on zero, for general inspection as specified in table IV. If one or more defects are
found, the lot shall be rescreened and defects removed. After screening and removal of defects, a new sample of
parts shall be randomly selected in accordance with table IV. If one or more defects are found in the second sample,
the lot shall be rejected and shall not be supplied to this specification.
TABLE IV. Sampling plan for group A inspection.
Lots Size
Sample Size
1/
2 to 12
*
13 to 150
13
151 to 290
20
291 to 500
29
501 to 1,200
34
1,201 to 3,200
42
3,201 to 10,000
50
10,001 to 35,000
60
35,001 to 150,000
74
150,001 to 500,000
90
500,001 and over
102
1/. * Indicates entire lot must be inspected.
4.5 Detailed examination.
(a) Every part of Microphone M-29( )/U shall be examined and measured for compliance with the drawings and
specifications on Drawing and Data List BC-DL-85585 (see 3.2).
(b) Every part of Microphone M-52( )/U shall be examined and measured for compliance with the drawings and
specifications on Drawing and Data List SC-DL-76334 (see 3.2).
4.6 Dielectric strength and insulation resistance. A potential of 500 volts DC shall be applied for not less than 2
seconds between each conductor and the remaining conductors connected together and to the exposed metal parts.
Immediately after the dielectric-strength test, the Insulation resistance shall be measured with a galvanometer or
other instrument approved by government inspector, using a DC potential of 500 volts, applied for not less than 2
seconds between each conductor and the remaining conductors connected together and to the exposed metal parts
(see 3.5).
4.7 Service conditions and operational tests.
4.7.1 Temperature. The microphone shall be subjected to the temperature cycle shown. Operation test shall be
made at 150°F (65.5°C), 77°F (25°C), -40°F (-40°C) and repeat 77°F (25°C) in accordance with method 503,
4.7.2 Humidity test. Subject the microphone to continuous cycling for a total of five 48 hour cycles. Each cycle
shall be in accordance with method 507 of MIL-STD-810. No repair or replacement of parts shall be made.
Afterwards there shall be no corrosion of metal parts or binding of moving parts and the microphone shall meet the
4.7.3 Operation. The microphone shall be connected to an amplifier and loudspeaker capable of indicating
operation of the microphone when spoken into. A test circuit shall be provided indicating continuity of the switch cord,
and connecter or plug when the switch is activated. (See 3.6).
4.7.4 Switch life test. The switch shall be tested by operating it for 500,000 make and break cycles at a rate of not
less than 25 cycles per minute. The switch contacts shall open and close a one ampere current at 24 volts through a
resistance load. Electrical counters shall be placed in each switch circuit and a mechanical counter on toe
mechanism for operating the switch. At the completion of 500,000 operational cycles the difference in reading
between either electrical counter and the mechanical counter shall, not exceed 1,000 operations (see 3.3).
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