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Environmental service condition |
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|  MIL-T-48621A (AR)
3.3 Environmental service condition.
3.3.1 Baseline data. Prior to any environmental tests of the
Noise Tester, he following test shall be performed at Standard
Ambient conditions: With equipment connected as shown in Figure
3, a qualified good Microwave Power Source (Table 111, Item 18)
shall be noise loaded at the O MOD INPUT port with an External Noise
Source (Item 26), so that with an Input signal to the Noise Tester
of +10 dBm at any frequency between 9140 and 9250 MHz, the NOISE
I
INDICATOR meter will read within the limits defined by the black
band when measuring the Source on any of the three bands. The
levels of in injected noise required to achieve "black-line" for each
band (as read on the True RMS Voltmeter, Item 28) end the power
level indicated on the input monitoring Power Meter (Items 6, 8)
shall be recorded as Baseline Data.
3.3.2 Repeatability. Subsequent to any environmental testing
of the Noise Tester, he following test shall be performed: With
equipment connected as shown in Figure 3, the Baseline Data shall be
noise loaded with the same level of External Noise as recorded in
the Baseline Data for the band under test. The Variable Waveguide
Attenuator (Item 16) shall be adjusted to obtain a black line center
meter reading on the Noise Tester, when it is set up for noise
measurement of the band under test. The resultant level indication
on the Input monitoring Power Meter (Items 6, 8) shall be within
+ 2 dB of the same level recorded in the Baseline Data.
3.3.3 Physical characteristics. The Noise Tester is housed in
a Style E enclosure, as defined In MIL-T-28800. The enclosure has
external dimensions of 12 In H x 16 In W x 15.5 in L, and has an
internal volume of 1.7 cubic feet. The Noise Tester in its
enclosure weighs 53 pounds.
3.3.4 Reliability. The Noise Tester shall be capable of
meeting the requirements for Type I reliability as defined in MIL-T-
28800, i.e., a minimum MTBF (Mean Time Between Failure) of 1000
hours `for continuous and intermittent operation, for the
environmental conditions specified herein 3.3.6 - 3.3.1.3.
3.3.5 Maintainability. The Noise Tester shall consist of
seventeen non-repairable major subassemblies, all replaceable at the
Direct Support level of maintenance. As such, the Noise Tester
shall meet the requirements for Type I maintainability as defined in
MIL-T-28800 .
3.3.6 Environmental. Pretest requirements as referenced in
MIL-STD-810, paragraph 3.2, shall be confined to the retirements of
paragraph 3.3.2 of this specification.
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