MIL-DTL-87104C
4.6.4.2 Vibration test (see 3.5.3.4). The vibration test shall determine the assembly's ability to withstand various
frequencies of vibration without degradation of the electrical performance.
4.6.4.2.1 Test setup.
4.6.4.2.1.1 Test configuration. The assembly shall be installed on the vibration table to simulate the same physical
configuration as would be encountered if the item were attached to an antenna assembly. One end of the cable
assembly shall be mated to a connector receptacle that is mounted on the vibration table, and the other end of the
cable shall be mated to a connector receptacle that is mounted to a rigid structure off the vibration table. Clamps or
supports shall not be used within 18 inches (457.2 mm) of the connector that is located on the vibration table.
4.6.4.2.1.2 Test conditions.
a.
The specified vibratory accelerations or displacement levels shall be maintained at the receptacle that is
mounted on the vibration table. Displacement levels shall be monitored at various locations on the test
sample.
All frequency measurements shall be accurate within ± 5 percent.
b.
All displacement or acceleration measurements shall be accurate within ± 10 percent.
c.
d.
The motion of the vibrator table shall be simple harmonic motion with not more than 20 percent distortion.
4.6.4.2.2 Procedure. The vibration test shall be performed with the motion applied in the direction of each of three
mutually orthogonal axes, at three temperatures: room ambient (see 4.3.1.1, -53.8°C, and +71.1°C; and in two
modes: frequency range scans and resonant endurance runs.
4.6.4.2.2.1 Test sample. The test sample shall be subjected to examination of product, procedure II (see 4.6.1.2);
VSWR, procedure II (see 4.6.2.1.2); and RF insertion loss, procedures I and II (see 4.6.2.3.2 and 4.6.2.3.3) at room
ambient temperature.
4.6.4.2.2.2 Frequency range scans. The frequency range scans shall be conducted under the conditions specified
herein.
4.6.4.2.2.2.1 Amplitude. Unless otherwise specified in the detail specification, the test sample shall be subjected
to a simple harmonic motion having an amplitude of either .2 inch (5.08 mm) double amplitude (maximum total
excursion), or ± 1 g, whichever is less, between the approximate limits of 5 and 18 Hz; and .06 inch (1.52 mm) double
amplitude (maximum total excursion), or ± 15 g, whichever is less, between the approximate limits of 18 and 2,000
Hz.
4.6.4.2.2.2.2 Frequency range. The vibration frequency shall be varied logarithmically between the approximate
limits of 5 and 2,000 Hz.
4.6.4.2.2.2.3 Sweep and duration. The entire frequency range of 5 to 2,000 Hz and return to 5 Hz shall be
traversed in 20 minutes. This cycle shall be performed 12 times in each of three mutually perpendicular directions
(total of 36 times), so that the motion will be applied for a total period of approximately 12 hours. Interruptions will be
permitted, provided the requirements for the rate of change and test duration are met. Completion of cycling within
any separate band is permissible before going to the next band.
4.6.4.2.2.2.4 Other tests. The assembly shall be sequentially subjected to the tests specified in 4.6.2.1.2, 4.6.2.3.2
and 4.6.2.3.3 while performing the vibration test procedures.
4.6.4.2.2.2.5 Temperature conditions. The frequency range scans shall be conducted at room ambient
temperature (see 4.3.1.1), -53.8°C, and +71.1°C, with two-thirds of the frequency range scans being conducted at
room ambient temperature, one-sixth of the scans at -53.8°C, and one-sixth of the scans at +71.1°C.
4.6.2.4.2.2.6 Resonant frequencies. During the entire frequency range scans, the test sample shall be monitored
by accelerometers for resonant frequencies.
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