MIL-DTL-55668 Cord, Electrical; Audio, Subminiature \(Retractile And Straight\)This specification covers subminiature audio helical retractile cords and straight cords with either stranded wire or tinsel wire conductors, for accessories associated in for the use with microphone, telephone, switchboard, and associated communication equipment. These cords are intended for operations at audio frequencies and temperatures from -55 Degrees C to +85 Degrees C with a high degree of flexibility. Each retractile cord is designed for extension in normal service up to 6 times its nominal retracted helical length.

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MIL-DTL-55668D

4.7.16 Humidity cycling. The test specimen shall be a finished cord which has passed the voltage

withstand and insulation resistance tests as specified in table IV. The cord shall be placed in a humidity

chamber, and the ends of the cord brought out through the walls of the chamber for electrical

measurements. The humidity cycle shall be in accordance with MIL-STD-202, method 106, except step

7. Voltage withstand and insulation resistance shall be measured before start of the environmental cycle

and during the 10th cycle, after step 6, at room temperature and 90-100 percent relative humidity (RH),

with the specimen in the chamber, in accordance with 4.7.13 and 4.7.14, and shall meet the requirements

in table IV. The specimen shall then be removed from the chamber and subjected to the bending flex test

of 4.7.10 as specified in table IV.

4.7.16.1 Alternate humidity cycle. An alternate method of humidity cycling is as follows:

Step A: 16 �1/2 hours at 65 C at 90-100 percent RH

Step B: 8 �1/2 hours at room temperature at 90-100 percent RH

Voltage withstand and insulation resistance measurements shall be made before start of the

environmental cycle and after 4 but not more than 6 hours have elapsed in step A of the 10th cycle, with

the specimen still in the chamber.

4.7.17 Simulated storage. The test specimen shall be a completed cord. The cord shall be aged in a

circulating air oven for 336�2 hours at 85�1 �C, then cooled at room temperature for a minimum of 24

hours. Effects of plasticizer migration or loss shall be determined by testing voltage withstand, insulation

resistance, and low temperature rapid extension as specified in 4.7.13, 4.7.14, and 4.7.9, and comparing

with the requirements in table IV.

5. PACKAGING

5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the

contract or order. When packaging of materiel is to be performed by DoD or in-house contractor

personnel, these personnel need to contact the responsible packaging activity to ascertain packaging

requirements. Packaging requirements are maintained by the Inventory Control Point's packaging

activities within the Military Service or Defense Agency, or within the military service's system commands.

Packaging data retrieval is available from the managing Military Department's or Defense Agency's

automated packaging files, CD-ROM products, or by contacting the responsible packaging activity.

6. NOTES

(This section contains information of a general or explanatory nature that may be helpful, but is not

mandatory.)

6.1 Intended use. The basic cord covered by this specification is intended for use in subminiature audio

helical retractile cords and straight cords for accessories such as microphone, telephone, switchboard,

and associated communication equipment operating at audio frequencies and temperatures from -55 C

to +85 C.

6.2 Acquisition requirements. Acquisition documents should specify the following:

Title, number, and date of this specification.

Type required (see 1.2).

Length and quantity of finished cords to be delivered.

Level of packaging and level of packing required (see 5.1).