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|  MIL-O-52374D
4.4.2 Burn-in. Operate the oscillator continuously with a 25 pF load applied for 100 hours. Failure of
any oscillator to operate for 100 hours continuously shall constitute failure of this test.
4.4.3 Normal operation. Connect the oscillator to the circuit shown in figure 4. Operate the oscillator
under all load and input conditions specified in table I. Failure to meet the requirements of 3.7 shall
constitute failure of this test.
4.4.4 Environmental temperature. Place the oscillator in a test chamber and gradually, in not less than
30 minutes, raise the temperature to +68C and hold at the temperature for a minimum of 2 hours. At the
end of this 2 hour period, gradually in not less than 15 minutes, lower the chamber temperature to +52C
and hold at this temperature for a minimum of 30 minutes. At the end of this period, operate the oscillator
with a total capacitative lead of 25 pF. Measure the input current, (mA) (see figure 4), output voltage and
of 25 pF. Measure the input current, (mA) (see figure 4), output voltage and output frequency and record
these values. Repeat the above procedure with total output frequency and record these values. Repeat
the above procedure with total capacitive loads of 15 pF (no load) and 55 pF (full load). Remove the
oscillator from the chamber to room temperature and hold at this temperature while operating for not less
than one hour. Monitor and record the output voltage. After recording the voltage, inspect for damage.
Replace the oscillator in the chamber and gradually, in not less than 30 minutes, reduce the chamber
temperature to -54C and hold at this temperature for two hour. During the final hour of this period,
reduce the atmospheric pressure to 20 inches of mercury and repeat the tests specified above that were
performed at +52C. At the conclusion of these tests increase the atmospheric pressure to 30 inches of
mercury, remove the oscillator from the chamber and hold, while operating at room temperature for not
less than one hour. Monitor and record the output voltage and inspect the oscillator for damage. Failure
to meet the requirements of 3.8, or evidence of damage or at the conclusion of the above testing shall
constitute failure of this test.
4.4.4.1 Humidity. Place the oscillator in a chamber with an internal temperature of +30C and a
relative humidity of 90 to 98 percent and soak for 4 hours. Raise the temperature of the chamber to
+50C in not more than 2 hours. Maintain the relative humidity of 90 to 98 percent and soak for 4 hours.
Lower the temperature of the chamber to +30C in not more than 2 hours. This constitutes one complete
cycle as shown in figure 3. Perform the above cycle six times. At the conclusion of the 6 cycles operate
the oscillator with 6.75 V dc input and a 25 pF load across the output. Failure to produce an output of
2,700 100 volts or evidence of damage shall constitute failure of this test.
4.4.5 Shock. Test the oscillator in accordance with test condition C, method 213 of MIL-STD-202.
Mount the oscillator securely to the shock testing apparatus. While the oscillator is operating subject the
oscillator to six 100 g shock impulses applied in each of three mutually perpendicular directions. Monitor
the output voltage before, during and after the application of the shock pulses. Inspect for damage.
Failure to meet the requirements of 3.9 shall constitute failure or this test.
4.4.6 Vibration. Secure the oscillator to the vibration table. Vibrate the oscillator with simple harmonic
motion in three mutually perpendicular planes over a frequency range of 10 to 55 Hz with an amplitude of
.10 inch total excursion. In 1 minute vary the frequency from 10 Hz to 55 Hz and return to 10 Hz. Repeat
this frequency sweep 10 times. Failure to meet the requirements of 3.10 shall constitute failure of this
test.
4.4.7 Rise time. Place the oscillator in the environmental chamber and adjust the temperature to
+52C. Hold at this temperature for 30 minutes. With a total capacitive load of 55 pF adjust the light
source (see figure 4) for full load condition. Open S1 and discharge (short V2) the multiplier completely.
Close S1 and adjust power supply to 6.75 V dc and measure the rise time and input current required for
the oscillator to start and reach steady-state condition. Repeat the above procedure at -54C and a 6.0
volt input. Failure to meet the requirements of 3.11 shall constitute failure of this test.
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