MIL-DTL-25708F
Step 1.
With antenna de-energized, adjust chamber to step 1 conditions listed above. After antenna
temperature is stabilized, maintain conditions for 2 hours.
Step 2.
With antenna de-energized, adjust chamber to step 2 conditions, and maintain. After antenna
temperature is stabilized, operate antenna at lowest specified input voltage. The antenna shall
operate satisfactorily immediately following the specified warm-up time. All characteristics likely to
be affected by low temperature shall be checked first. If time to check exceeds 15 minutes
beyond the warm-up time, the test item shall again be stabilized at the step 2 temperature and the
operational check continued.
Step 3.
With antenna de-energized, adjust chamber to step 3 temperature and stabilize antenna
temperature. Energize the antenna at highest specified input voltage and adjust chamber
pressure to step 3 altitude. At step 3 pressure and temperature, the antenna shall be checked for
satisfactory operation.
Step 4.
With antenna de-energized, adjust chamber to step 4 conditions. After antenna temperature has
stabilized, open chamber door and permit frost to form (use artificial moisture, if required) on
antenna. The door shall remain open long enough for the frost to melt, but not long enough for the
moisture to evaporate. The chamber door shall be closed and the test item operated at the
highest specified input voltage to ascertain satisfactory operation immediately following the
specified warm-up time. The antenna shall be energized and de-energized at least three times.
Step 5.
Adjust the chamber to standard ambient conditions. After antenna temperature has stabilized, an
operational and performance check of the antenna shall be made.
Step 6.
With antenna de-energized, adjust chamber to step 6 conditions. Stabilize antenna temperature
and maintain for 16 hours. Visually inspect, if practicable.
Step 7.
With antenna de-energized, adjust chamber to step 7 conditions. After antenna temperature is
stabilized, while maintaining chamber temperature, operate the antenna continuously at the
highest specified input voltage for 4 hours, recording thermal sensor readings of antenna
temperature every 30 minutes. At the end of the 4 hour time period, while maintaining the test
conditions, the test item shall be checked for satisfactory operation.
Step 8.
With antenna de-energized, adjust chamber to step 8 conditions. After antenna temperature has
stabilized, the antenna shall be operated at the highest specified input voltage for four time periods
each of 30 minute duration. The first three time periods of operation shall be followed by a 15
minute period with antenna de-energized. The test item shall be checked for satisfactory
operation during each operating time period. Thermal sensor readings of antenna temperature
shall be recorded every 10 minutes of antenna operation.
Step 9.
With antenna de-energized, adjust chamber to step 9 conditions. After antenna temperature is
stabilized, antenna shall be operated at the highest specified input voltage for four time periods
each of 10 minutes. The first three periods of operation shall be followed by a 15 minute period
with the antenna de-energized. Check antenna for satisfactory operation during each operating
time period. Thermal sensor readings of antenna temperature shall be recorded at the beginning
and the end of each operating period.
Step 10. With antenna de-energized, adjust chamber temperature to step 10 conditions. Stabilize antenna
temperature. Operate antenna at highest specified input voltage, and adjust chamber pressure to
step 10 altitude. Maintain test conditions for 4 hours. Thermal sensor readings of antenna
temperature shall be recorded every 30 minutes. At the end of the 4 hour period, while
maintaining test conditions, the antenna will be checked for satisfactory operation.
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