MIL-PRF-1/1335H
TABLE I. Testing and inspection - Continued.
7/
In performing this test, the cathode by-pass capacitor should be charged to +6 volts prior to insertion of the tube into the test
socket to prevent high-initial surge current.
8/
Low-frequency vibration. Test shall be performed as follows: The tube shall be vibrated with simple harmonic motion in each of
two planes; first, parallel to the cylindrical axis; second, perpendicular to the cylindrical axis and perpendicular to major axis of
terminal lug.
9/
Sweep-frequency vibration. Test shall be performed as follows:
a.
The frequency shall be increased from 100 to 2,000 Hz with approximately logarithmic progression in 3 ± 1 minutes. The
return sweep (2,000 to 100 Hz) is not required.
b.
The tube shall be vibrated with simple harmonic motion in each of two planes; first, parallel to the cylindrical axis; second,
perpendicular to the cylindrical axis and parallel to a line through the major axis of a terminal lug. At all frequencies from 100
to 2,000 Hz, the total harmonic distortion of the acceleration waveform shall be less than 5 percent.
c.
The peak acceleration shall be maintained at 10 ± 1.0 G throughout the test.
d.
The value of the alternating voltage, Ep, produced across the resistor, Rp, as a result of the vibration shall be measured with
a suitable device having a response of the RMS value of the voltage to within ± 0.5 dB of the response at 400 Hz for the
frequency range of 100 to 3,000 Hz, and having a bandpass filter with an attenuation rate of 24 dB per octave below the low-
frequency cutoff point of 50 Hz and above the high-frequency cutoff point of 5,000 Hz. The meter shall have a dynamic
response characteristic equivalent to, or faster than, a VU meter (operated in accordance with Standard ASA No. C 16.5-
1954).
10/
Sweep-frequency vibration fatigue. Test shall be performed as specified in MIL-STD-1311 method 1031, except that the tubes
shall be vibrated for a total of 6 hours, that is, 3 hours in each of two directions; first, parallel to the cylindrical axis; second,
perpendicular to the cylindrical axis and parallel to a line through the major axis of a terminal lug.
11/
This test shall be performed during the initial production and once each succeeding 12-calendar months in which there is
production. An accept on zero defect sampling plan shall be used, with sample of three tubes with an acceptance number of zero.
In the event of failure, the test will be made as a part of conformance inspection, part 2, with an acceptance level of 6.5 (see 12/).
The regular "12-calendar month" sampling plan shall be reinstated after three consecutive samples have been accepted.
12/
This specification sheet uses accept on zero defect sampling in accordnce with MIL-PRF-1, table III.
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