MIL-DTL-55288E
4.7.8 Flexing test (see 3.7.7). One base assembly spring shall be flexed 40,000 cycles with each cycle consisting
of a deflection of the top of the spring +30° from the unflexed position, to -30°, and return to normal. The 40,000
cycles shall be accomplished by rotating and cycling the spring approximately 13,333 cycles at each of three (3) 120°
positions. A second spring shall then be flexed 5,000 cycles, with one cycle consisting of a deflection of +90° from
the unflexed position, to -90°, and return to normal. The 5,000 cycles shall be accomplished by rotating the spring
approximately 1,666 cycles at each of three (3) 120° positions. The test shall be performed at a temperature of -
40°F. The flexing rate shall be 10 ± 1 cycle per minute. Tests of springs shall be performed with rf cable SM-D-
542043 assembled in it in holders SM-D-542060 and SMC-542059 or equivalent fixtures. The rf cable shall be tested
for continuity before and after the flexing procedure.
4.7.9 Fungus (see 3.7.8). The antenna shall be tested in accordance with method 508, procedure I of MIL-STD-
810. The antenna matching unit case (SM-D-542066) shall be opened, the AT-1095/VRC and AS-1730/VRC
elements shall not be connected to each other or the MX-6707/VRC base, the parts and materials of the antenna
internal assembly, the interior of the case, the interior surfaces of the cable mount assembly (SM-D-542042), as well
as the exterior of the antenna shall be sprayed with the spore suspension. The antenna shall be subjected to the test
in this open condition. There shall be abundant growth colonization (see 6.10) on 50 percent or more of the control
items after 7 and 28 days. The inability of the antenna to meet the requirements of 3.7.8 shall constitute failure of this
test.
4.7.10 Salt fog (see 3.7.9). The equipment and assemblies shall be exposed in their operating configuration to salt
fog in accordance with method 509 of MIL-STD-810 for 48 hours. Equipment and assemblies shall not be opened or
operated during the test cycle. Immediately before and after the test cycles, the equipment and assemblies shall be
tested for compliance with the requirements specified in 3.7.9.
4.7.11 Rain test (see 3.7.10). The Antenna Matching Unit Base MX-6707 shall be subjected to the blowing rain
and water-tightness tests of procedures I and II in method 506 of MIL-STD-810. The choice of related test conditions
for each of the two tests are as follows:
Condition
Procedure I
Procedure II
Test Item Configuration
Operational, on tank and wheeled
Washing with high pressure hoses
vehicles.
on both
Rainfall Rate/Pressure
5 inches per hour
150 psi at 3 feet
Wind Velocity/GPM
40 mph
100
Duration
45 minutes
10 minutes
Rain temperature +18°F minimum
Hose water temperature +18°F
Temperature, Unit Base, °F
at beginning.
minimum at beginning.
4.8 Electrical tests.
4.8.1 Voltage standing wave ratio (VSWR).
4.8.1.1 Standard test condition. All electrical free space measurements, unless otherwise specified, shall be made
in a reflection free environment. The test setup shall be located in an area that is away from any structure or
geographical feature which would produce reflections and measurably alter the free space impedance. The antenna
under test shall be elevated sufficiently to minimize the effects of terrain and all tests shall be performed over a
ground plane consisting of a solid 10 foot by 10 foot copper sheet ground plane. Input impedance shall be referred to
50 ohms and the frequency of the source shall be accurate to within ±0.1 MHz. The magnitude of rf leakage in any of
the test equipment plus any subassembly of the AS-1729/VRC Antenna shall be sufficiently low so that it cannot
introduce errors into any electrical measurement.
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