MIL-F-18327F
4.7.8.4 Special characteristics. Special characteristics shall be measured as specified (see 3.1).
4.7.9 Stability at temperature extremes (see 3.12). Filters shall be exposed to a temperature of -55°C +0°, -3°C for
the minimum number of hours specified in table XI (see 3.1). At the end of this exposure period and while the filters
are at this temperature, the electrical characteristics (see 3.1) shall be measured as specified in 4.7.8. The filters
shall then be exposed at the maximum operating temperature for the class, +3° -0°C, for the minimum number of
hours specified in table XI (see 3.1). At the end of this exposure period and while the filters are at this temperature,
the electrical characteristics (see 3.1) shall again be measured as specified in 4.7.8. The filters shall then be
subjected to the dielectric withstanding voltage test specified in 4.7.6.
TABLE XI. Exposure time at temperature extremes.
Weight of filter
Minimum time
Pounds
Hours
0.3 and below
1
Above 0.3 to 3 inclusive
2
Above 3 to 30 inclusive
4
Above 30 to 50 inclusive
8
4.7.10 Life (at elevated ambient temperature) (see 3.13). Filters shall be tested in accordance with method 108,
MIL-STD-202. The following details and exceptions shall apply:
a.
Distance of temperature measurements from specimens: 6 inches.
b.
Test temperature and tolerance: Maximum operating temperature for the class.
Tolerance shall be +10°, -5°C.
c.
Operating conditions: Rated voltage at the reference frequency operating into the rated source and load
impedances.
(1)
Composition 1 filters (see 1.2.1.7) which dissipate less than 0.1 watt average output need not be
subjected to the foregoing phase of the life test.
(2)
DC operating voltages or requirements shall be applied as specified (see 3.1).
d.
Test condition letter (see 1.2.1.4):
(1)
F: For filters with life expectancy X.
(2)
D: For filters with life expectancy Y.
e.
Measurement after exposure: Dielectric withstanding voltage, insulation resistance, and electrical
characteristics shall be measured as specified in 4.7.6, 4.7.7, and 4.7.8, respectively. Filters shall then be
examined externally and internally for evidence of leakage and physical damage. Before measurements,
all units shall be removed from the test chamber and stabilized at room temperature.
4.7.11 Temperature rise (when specified, see 3.1) (see 3.14). Filters rated at more than 0.8 watt average output
shall be tested using one or more thermocouples, as required, attached to the outside of the filter. Rated voltage
(see 3.1) shall be applied to the filter for a sufficient period until two consecutive thermocouple measurements, taken
30 minutes apart, are the same. The temperature rise shall be the difference between the temperature obtained and
the ambient temperature existing at this time. The filters shall then be examined for evidence of leakage and physical
damage.
25
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business