MIL-PRF-1/1705C
TABLE I. Testing and inspection - Continued.
19/ The tuner dial shall be set for frequency F5. Cooling air shall be applied so that under test condition 2, the temperature (TA) as
measured at the indicated area in accordance with figure 1 shall fall between 80°C and 100°C after thermal equilibrium has been
reached. Measure and record the actual frequency. The tube shall then be allowed to cool with no voltages applied for at least 15
minutes before the following test. Anode voltage, as specified for test condition 2, shall be applied after a maximum of 180 seconds
of heater warm-up time. The frequency as measured 15 ± 5 seconds after application of pulse voltage shall be within the limit
specified from that measured and recorded at the start of the test. The frequency shall then be measured at approximately 3 minute
intervals until 20 minutes have elapsed. A graph of frequency versus time shall be constructed using the data. The maximum
frequency deviation from the previously recorded thermal equilibrium frequency shall not exceed the limit specified.
20/ The tube shall be placed within a test chamber wherein a temperature of 70°C Is maintained. The tube shall be exposed to this
temperature for a period of 4 hours, at the conclusion of which and within 5 minutes, the tube shall be transferred to a chamber
having an internal temperature of -55°C. The tube shall be subjected to this temperature for a period of 4 hours. This constitutes
one cycle. The number of complete cycles shall be three. The duration of the exposure at each extreme temperature shall not be
less than that specified and may be extended to over-night exposure to prevent interruption of the transfer cycle. At the conclusion
of the third cycle, the tube shall be removed from the test chamber, returned to ambient (25°C ± 5°C) temperature, and within a
period of one hour shall meet Resettability, paragraph 8 of MIL-STD-1311 test method 4223 and Tuning Rate, paragraph 2.3 of test
method 4223 in MIL-STD-1311.
21/ The magnetron shall be vibrated in each of three mutually perpendicular planes (see figure 1) through the following amplitudes for
both resonance and cycling tests:
5 Hz to
14 Hz. . . . . . . . .
0.375 inch D. A.
14 Hz to 200 Hz. . . . . . . . .
2g
200 Hz to 1,000 Hz. . . . . . . . .
1g
1,000 Hz to 1,500 Hz. . . . . . . . .
0.5 g
Any mechanical resonance that may be encountered during the test shall be sustained at the frequency and specified amplitude
which produced the resonance for the period of time specified in the standard. W hen more than one resonant frequency condition
is encountered, the test shall center on the frequency that produces the most pronounced resonant condition. Should more than
one pronounced resonant condition be encountered, the time at resonance shall be equally divided between each of the resonant
conditions.
22/ To demonstrate compliance with this requirement, power output must be measured at the minimum and maximum power points in
the range from F1 to F5.
23/ The test shall be performed using a missing pulse detector, i.e., energy comparator. The detector shall be adjusted so that all
pulses missing more than 10 percent of the energy content shall be counted. The acceptable limit shall not exceed that specified.
The test interval shall be three minutes.
24/ The tube shall be mounted in a resonance free jig and vibrated while operating in each of three (3) mutually perpendicular planes
(see figure 1) through the following amplitude for cycling tests:
5 Hz to
15 Hz. . . . . . . . .
0.2 inch D. A.
15 Hz to
50 Hz. . . . . . . . .
2g
50 Hz to 250 Hz. . . . . . . . .
1.5 g
250 Hz to 1,000 Hz. . . . . . . . .
0.75 g
1,000 Hz to 1,500 Hz. . . . . . . . .
0.5 g
25/ The magnetron shall be mounted on a test plate and dropped 10 times on each of three mutually perpendicular planes parallel to the
reference planes A, B, and C in accordance with figure 1. The shock impulses shall have a duration of 11 ± 1 milliseconds as
measured at the one-quarter amplitude points. The acceleration shall be 15 g. No physical change shall result and the magnetron
shall meet the requirements of conformance inspection, part 1. This is a nondestructive test.
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