MIL-DTL-10392 Cord, Electrical \(Audio, Miniature\)This specification covers miniature audio cords with stranded wire conductors for use switch microphones, telephone, switchboards, and associated communication equipment. These cords are intended for use at potentials up to 300 volts \(rms\) at audio frequencies, and at temperatures from -40 degrees to +75 degrees C \(see 3.2 for individual types.\)

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MIL-DTL-10392F

4.5.10.2 Procedure. The specimens selected for checking the cord as whole shall be attached to the

proper size mandrel as specified in 4.5.10.2.1. The specimens shall be suspended vertically with lower

ends weighted sufficiently to keep specimens taut and to permit bending them without handling. The

mandrel and specimens shall be placed for at least 20 hours in the cold chamber at the specified

temperature (see 3.20.1). While at this temperature, the specimens shall be bent for seven close turns

around the mandrel at the rate of approximately fifteen turns per minute. After the test has been

complete, the jacket on the specimen of cord shall be examined for damage through a magnifying glass

of at least three diameter's magnification. The jacket shall be carefully removed and the individual

conductor insulation of all specimens shall be examined for damage with the magnifying glass. Only the

five inside turns shall be considered for evidence of damage.

4.5.10.2.1 Mandrels for cords. The mandrel for testing the cord shall be selected from the following

standard size mandrel diameters.

Mandrel diameters (in/mm)

0.500 (12.70)

0.680 (17.27)

0.840 (21.34)

1.050 (26.67)

NOTE: Dimensions are in inches. Metric equivalents are given for information only.

The size selected shall be the largest size which does not exceed three times the specified nominal

diameter of the cord.

4.5.10.2.2 Mandrels for insulation. The mandrel for testing the insulation apart from the cord shall be

selected according to the size of the conductor as follows:

Conductor size

Mandrel diameter (in/mm)

0.062 (1.57)

0.094 (2.39)

NOTE: Dimensions are in inches. Metric equivalents are given for information purposes.

4.5.11 Conductivity of fibers and yarns. The fibers and yarns shall be subjected to the following test:

One-half gram of material removed form the finished cord shall be boiled for 10 minutes in 60 to 70 cubic

centimeters of distilled water which has a conductivity of not more than 5 micro-ohms per centimeter cube

at 20� C. Enough distilled water shall then be added to make a volume of 100 cubic centimeters. The

conductivity of this solution shall be measures with alternating current and shall be determined as the

average of tow specimens removed from each sample unit. If the average thus determined exceeds the

requirement specified in 3.9, the sample unit shall be considered defective. A conductivity cell may be

used for this test.