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External tritium contamination. |
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|  MIL-M-70742 (AR)
3.5.4.2 Vibration "B". The Mount shall be vibrated in a
vertical plane at a constant frequency of 30 + 5 cycles per
seconds with an amplitude of 1/16 inch (1/8 + 1/64 inch total
excursion) for a period of five minutes plus or minus 15 seconds.
Subsequent to vibration there shall be no evidence of physical
failure.
3.5.5 External tritium contamination. Tritium shall not be
present on the external surfaces of the mount in excess of 1000
dpm/100 sq. cm.
(counter box area). The counter box area of
3.5.6 Sealinq
the mount shall be
capable of sustaining an internal pressure of
2.0 + .2 psi for a
period of 2 hours (minimum) without loss of
pressure in excess
of 0.2 psi.
3.5.7 Purging. The counter box area of the mount shall be
purged with dry nitrogen supplied at a pressure of 5 + .2 psi
until the dew point of the emergent gas is no higher than -25
degrees Fahrenheit. Purging apertures shall be quickly and
positively closed to minimize intermingling of external atmosphere
upon disconnecting of puring equipment.
3.5.8 Rain test. The mount shall meet the requirements of
Procedure I of the rain test of MIL-F-13926.
3.6 Performance.
The mount shall be positioned and
3.6.1 Orientation.
orientated as follows:
a. The mounting surface (internal surface) of the mount shall
be in a vertical plane.
b. The mount locating keyway shall be horizontal within 10
seconds.
The top locating surface for the telescope, shall be
parallel to the mount's locating keyway within 0.5 mil.
d. The elevation and cross level vial bubble shall be
centered.
e. The gunner's quadrant pads shall be level in reference to
location keyway within 0.2 mil.
f. The locating key for the telescope shall be parallel to
the vertical mounting surface within 1.0 mil.
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