MIL-PRF-1/1330G
TABLE I. Testing and inspection - Continued.
3/
Prior to this test, tubes shall be preheated a minimum of 5 minutes at the conditions indicated below. The 3-minute test is not
permitted. Test within 3 seconds after preheating. Grid emission shall be the last test performed on the sample selected for the
grid-emission test.
Ef
Ecc
Eb
Rk
Rg
V
V dc
V dc
Ohms
Meg
7
0
150
82
0.1
4/
The tube shall be tested as specified in MIL-STD-1311method 1002 with the exception that the specified voltage shall be applied
between the anode and grid.
5/
Tubes shall be tested as specified in MIL-STD-1311method 2126, except that they shall be first immersed in water at not more
than 5°C for 15 seconds and immediately thereafter subjected to the standard temperature cycle specified in MIL-STD-1311
method 2126. Tubes having high heater current of 300 mA or more shall be rejected as evidence of air leaks.
6/
Eg = 7.7 V ac, 60 Hz, applied to grid through 100 µF coupling capacitor. Grid is connected to ground through 3,300 ohms.
7/
Grid recovery. Test shall be performed as follows:
a. W ith tube under test (TUT) operating under specified conditions, adjust Ec for Ib = 3 mA dc.
b. Apply 5 volt pulse, 20 µs duration, 60 pps to the grid.
c. W ith application of pulse, measure undershoot (ĆIb) and change in average current (ĆIb).
8/
The heater-cycling life-test sample shall consist of 15 tubes and no tube failure shall be permitted. In the event of rejection of the
first sample due to failure of 1 tube, a second sample of 15 tubes shall be selected from the lot. Acceptance shall then be based
on the combined first and second samples. The total tube failures from the combined first and second samples shall not exceed
one.
9/
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 parallel to a line through the heater
contacts.
10/
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 perpendicular to a line through the heater contacts. 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 response to 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 cut-off point of 50 Hz and above the high-frequency cut-off 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)
11/
Sweep-frequency vibration fatigue. Test shall be performed as specified in 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 heater contacts.
12/
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 13/).
The "12-calendar month" sampling plan shall be reinstated after three consecutive samples have been accepted.
13/
This specification sheet uses accept on zero defect sampling in accordance with MIL-PRF-1, table III.
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