MIL-DTL-87104C
4.6.2.8.2 Procedure. The velocity of propagation test shall be conducted as follows:
a.
Calibrate the system over the design frequency range of the test sample with required adapters inserted in
the leg of the phase bridge to be used for the test sample. Record calibration line.
b.
Insert the test sample in the appropriate leg of the phase bridge and an equal length of air line in the other
leg. Note the length (L) of the test sample.
c.
Using the phase bridge, adjust the electrical length of the air line leg to obtain a phase balance across the
design frequency of the test sample. Note the added length (ĆL).
Calculate velocity of propagation (VP) of calibration line as follows:
d.
L
VP =
x 100%
L + ĆL
Sweep over the design frequency of the test sample. Note maximum deviation (φ in degrees) from
e.
calibration line.
Calculate minimum velocity of propagation VP (MIN) as:
f.
L
VP (MIN ) =
= 100%
C
(L + ĆL) +
360 f
Where:
C = the velocity of propagation in free space.
f = the frequency (in Hz) at which φ is measured.
g.
Using the data obtained, calculate the electrical length over the design frequency range of the cable
assembly, at 1.0-GHz increments starting at 1.0 GHz.
h.
Using the data obtained, calculate the time delay of the cable assembly at the frequencies specified in
4.6.2.8.2g herein.
4.6.2.8.3 Accept-reject criteria (see 3.5.1.10). The coaxial assembly shall be considered to have passed this test,
if the minimum velocity of propagation is greater than, or equal to, the value specified in the detail specification.
4.6.2.9 Thermal stability test (see 3.5.1.11). This test shall determine the thermal stability of the coaxial assembly.
4.6.2.9.1 Test setup.
4.6.2.9.1.1 Test equipment. Temperature chambers and measuring devices, as applicable, shall be required.
4.6.2.9.1.2 Test conditions. Tests shall be conducted under room ambient conditions (see 4.3.1.1), except that the
temperature shall be as specified under 4.6.2.9.2.
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