MIL-DTL-25707F
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.
Step 11. With test item de-energized, adjust chamber temperature to step 11 conditions. The antenna temperature
shall be stabilized, and the antenna shall be energized at the highest specified input voltage, while chamber
pressure is adjusted to simulate step 11 altitude. The antenna shall be operated for 4 time periods each of 30
minutes. The first three time periods of operation shall be followed by a 15 minute period of operation,
followed by a 15 minute period with the 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 12. With the antenna de-energized, adjust chamber temperature to step 12 conditions (following steps where a
change in temperature at low pressure is required, the pressure may be increased to ambient before changing
temperature and then returned to the required pressure following temperature stabilization.) The antenna
temperature shall be stabilized and the antenna shall be energized at the highest specified input voltage and
chamber pressure adjusted to step 12 conditions. Maintain for step 12 duration. Thermal sensor readings of
antenna temperature shall be recorded every 30 minutes. At end of 4 hours, while maintaining test
conditions, check antenna for satisfactory operation.
Step 13. With the antenna de-energized, adjust the chamber temperature to step 13 conditions and maintain. The
antenna temperature shall be stabilized. The antenna shall be energized at the highest specified input
voltage and the chamber pressure adjusted to step 13 altitude. The antenna shall be operated for four time
periods of 30 minutes. The first three time periods shall be followed by a 15-minute period with the antenna
de-energized. The antenna shall be checked for satisfactory operation during each operating time period.
Thermal sensor readings shall be recorded every 10 minutes of antenna operation.
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