MIL-DTL-24640C
4.7.18.1 Observation. Any of the following shall construe specimen failure:
a.
A specimen tensile strength which is less than that specified (see 3.1).
b.
A specimen elongation which is less than that specified (see 3.1).
4.7.19 Toxicity index. The toxicity index shall be determined as specified in Defence Standard 02-713. For
insulation materials, the toxicity index shall be calculated on the mass of insulation on 1 meter length of finished
wire size 22 AWG. For jacket and filler materials, the toxicity index shall be calculated on 100 grams of material.
(The toxicity index is derived from the chemical analysis of the products of combustion of the materials.)
4.7.19.1 Observation. Specimen failure shall be construed if any toxicity index is greater than that specified
(see 3.1).
4.7.20 Weathering. Jacket material shall be subjected to 720 hours of the xenon arc lamp weathering resistance
test in accordance with Section 1200 of UL Standard 1581.
4.7.20.1 Observation. Specimen failure shall be construed if the tensile strength and elongation retention is less
than 75 percent or if the specimen surface exhibits signs of cracking when examined using 3X magnification.
4.7.21 Tensile strength and elongation. Both aged and unaged specimens of the jacket material shall be tested
in accordance with Methods 3021 and 3031 of FED-STD-228. Unless otherwise specified in the applicable
specification sheet, there shall be 1 inch bench marks, 1 inch jaw separation, and a rate of jaw travel of 10 inches per
minute. The thickness of the specimen shall be measured using any suitable micrometer.
4.7.21.1 Observation. Specimen failure shall be construed if the tensile strength and elongation retention is less
than that specified herein or in the applicable specification sheet.
4.7.22 Shrinkage. A 12-inch specimen of cable shall be cut so that all components are flush at both ends.
Unless otherwise specified in the applicable specification sheet, the specimen shall then be aged at 136+3 °C for 6
hours in an air circulating oven. At the end of this period, the specimen shall be removed from the oven and allowed
to cool to room temperature. Shrinkage of the jacket shall then be measured to determine the total distance the
jacket has receded from both ends of the conductor.
4.7.22.1 Observation. Specimen failure shall be construed if the total shrinkage of the jacket is greater than
0.25 inch.
4.7.23 Weight. The weight of each lot of finished cable shall be determined from the length and weight of a
specimen not less than 10 feet long. The specimen shall be accurately measured and the resultant measurements
converted to pounds per 1000 feet. Lots failing to conform to the weight requirement specified in the applicable
specification sheet shall be rejected.
4.7.24 Cross linking proof. Cable jacket cross link verification shall utilize the hot creep test in accordance
with ICEA T-28-562. The procedure for jacket testing shall be modified to run at least 200 °C. Jacket percent of
elongation shall be as specified in the individual specification sheets (see 3.1).
4.8 Test methods (electrical).
4.8.1 Attenuation. This test shall determine the ability of completed cable, which is intended for the
transmission of data, voice, or control information, to propagate a signal at a frequency of 3 megahertz (MHz)
without causing an unacceptable reduction of signal amplitude.
4.8.1.1 Specimen. The specimen shall consist of a piece of completed cable, which shall have sufficient length
to exhibit an electrical attenuation of not less than 3 decibels (dB) at the specified test frequency (see 3.1).
Individual transmission lines within this specimen (where each single insulated conductor plus surrounding shield or
each insulated conductor pair plus surrounding shield is considered to be a transmission line) shall be selected for
testing as follows.
a.
Specimens containing four or fewer transmission lines: Every transmission line shall be tested.
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