MIL-DTL-55288E
(0.76 mm). In each of the three perpendicular directions, change the frequency in discrete steps of one
cycle per second and maintain each frequency for at least 10 seconds.
c.
At the completion of the test, the base assembly resonance test (see 4.8.2), shall be performed to
determine compliance with 3.8.1.
4.7.4.2 Vibration, whip assembly (see 3.7.4.2). The whip assembly shall be vibrated to determine its natural
frequency exhibiting the highest vibration amplitude, and then the whip assembly shall be vibrated for two hours at
this natural frequency. At the completion of the test, the whip antenna test of 3.8.4 shall be performed to determine
compliance with 4.8.4. The total excursion of the applied vibration shall be not less than .030 inch (0.76 mm).
4.7.5 Bounce test (see 3.7.5). The Antenna AS-1729/VRC shall be tested on a package tester, type 1000-SC, as
made by the L.A.B. Corporation, Skaneateles, NY or equal. Accessories shall be selected from those listed on
CECOM DWG SC-A-46439. The tests shall be as follows:
a.
Secure the equipment to the 48 inch by 48 inch (1219 mm by 1219 mm) vehicular adapter plate, in the
same manner as it would be mounted in a vehicle. The adapter plate shall be free of cracks and broken
welds, and all unused holes except the 2-inch (51 mm) breather holes shall be plugged. No part of the
mounted surface shall be less than 7 inches (178 mm) from the edge of the adapter plate.
b.
Cover the tester bed with a panel of .500 inch (12.70 mm) plywood, with the grain parallel to the drive
chain. Space sixpenny nails with heads below the surface, at 6-inch (152.4 mm) intervals around all four
edges and at 3-inch (76 mm) intervals in a 6-inch (152 mm) square in the center.
c.
Place the adapter plate on the bed of the package tester. Limit the lateral motion, by wooden fences, to not
more than 3 inches (76 mm) and not less than 1 inch (25 mm). Additional barriers may be used to
safeguard personnel, provided that the fore and aft motion of the adapter plate against the backstop is not
restrained.
d.
Operate the package tester, shafts in phase, for a total of 3 hours at 283 ± 1 rpm. Turn the adapter plate
90 degrees at the end of each 45 minutes, each time in the same direction.
e.
During the final 15 minutes of bounce testing, the antenna is to be energized by a 1,000 cycle modulated rf
carrier of minimum power in the frequency range from 30 to 75.95 MHz. A Government approved
communication type receiver located a minimum of 100 feet from the antenna under test shall be tuned to
the frequency of the AS-1729/VRC under test. The received signal shall be clear with no interruptions.
f.
At the completion of three hours of bounce testing, the equipment shall be tested to 4.8.1.2 and 4.8.2 to
4.7.6 Shock test, ballistic (see 3.7.5). The test shall be conducted on the "Shock Testing Machine for Light Weight
Equipment" shown in MIL-S-901. The antenna shall be secured in its normal operating position to the steel test plate
by means of the same fasteners used for vehicular installation of the equipment. The test shall consist of a total of 9
blows. The sequence of the test blows is to be: (a) 1-foot, and 5-foot blows on the back; (b) 1-foot, 3-foot, and 5-
foot blows on the top; and (c) 1-foot, 3-foot, and 5-foot blows on the side. As an alternative to reorienting the test
plate for the blows on the side of the plate, equivalent rotation of the equipment under test is permissible. At the
completion of the 9 blows, the antenna shall be tested to 4.8.2 and 4.8.4 to demonstrate compliance with 3.8.1 and
4.7.7 Impact (see 3.7.6). The Antenna AS-1729/VRC, secured on a vehicle in a normal operating position, shall
be subjected to 25 repeated blows in any direction, against a 4 inch by 4 inch (101.6 mm by 101.6 mm) oak beam,
when the vehicle is traveling at a rate of 25 miles per hour. The point of impact shall be at the mid-point of the whip
assembly. The oak beam shall be stationary at the point of impact. After being subjected to this test, the antenna
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