MIL-PRF-1/1165F
5.
Prior to this test, the tubes under test (TUT) shall be preheated for 5 minutes at the conditions specified below. Test with
in 3 seconds after preheating. The 3-minute test shall not be permitted. Grid emission shall be the last test performed on
the sample selected for the grid emission test.
Ef
Eb
Ec
Rk/k
Rg/g
MegΩ
V
Vdc
Vdc
Ohms
7.5
250
0
1,300
1.0
6.
Tie 1k to 2k; 1 g to 2g; and 1a to 2a.
7.
The rejection level shall be set at the VU meter reading obtained during calibration.
8.
Maximum total distortion of the filament supple voltage shall be 5 percent. The frequency response of the peak-to-peak
measuring device from 20 to 5,000 Hz shall be within 0.5 dB of its response at 400Hz. Ground leads except those for the
cathode and heater lead No. 3. Measure hum voltage across specified Rk.
9.
The tube shall be rigidly mounted on at able vibrating so that the instantaneous values of acceleration shall constitute
approximately a " white noise" spectrum which is free from discontinuities from 100 to 5,000 Hz and such that the rms
value of acceleration for frequencies outside this band shall constitute no more than 5 percent of the total rms
acceleration. The spectrum of instantaneous acceleration shall be such that each octave of bandwidth delivers 2.3 ± 0.2
G's rms acceleration. With this the case the rms value of acceleration for any bandwidth within the spectrum is equal to:
GRMGrms 2.3 3.32 log10 ( F 2 / F1)
Where F2 and F1 are the upper and lower frequencies respectively of the band under consideration. The degree of
clipping of the clipping of the peak accelerations shall be such that the peak value of accelerations shall be such that the
peak value of acceleration is at least 15 G's. Half the tubes in the sample shall be vibrated in position X, the other half in
position Y. The voltage (ep) produced across the resistor (Rp) as a result of vibration shall be coupled through a
compensation amplifier to a low-pass filter. The compensating amplifier shall have a high-input impedance (250 K ohms
or more) and shall be adjusted to compensate for any insertion losses in the filter. The combined frequency response of
amplifier and filter shall be flat within± 0.5 dB from 50 to 8,000 Hz, shall be down no more than 5 dB at 10,000 Hz and 20
Hz, and down at least 30 dB at 13,000 Hz. For reading peak-to-peak value of output voltage, the filter output shall be fed
directly to the input of a Ballantine Model 305 peak-to-peak Electronic Voltmeter, or equal, while the rms value shall be
measured with the Hewlett Packard Model 400 c, or equal. The impedance of the anode and screen voltage supplies shall
not exceed that of a 40 μF capacitor at 10 Hz.
10. A grid resistor of 0.1 MegΩ shall be added except when a thyratron-type short indicator is used.
11. This test shall be conducted on the initial lot and thereafter on a lot approximately every 12 months. When on lot has
passed, the 12-month rule shall apply. In the event of lot failure, the lat shall be rejected and the succeeding lots shall be
subjected to this test until a lot passes.
12. Envelope temperature (TE) requirements, when measured in accordance with the temperature by conduction-band
measurements (MIL-STD-1311 method 1226), will be satisfied if a TUT having bogey Ib (± 5 percent) under normal test
conditions, is determined to operate at or above minimum specified temperature at any position in the life-test rack.
13. The allowable defectives per characteristic shall not be greater than 1 for first sample and shall not be greater than 3 for
combined samples. Total defective shall be 2 and 5, respectively.
14. Revision letters are not used in this revision to identify changes with respect to the previous issue, due to the
extensiveness of the changes.
15. Insert a cold tube into the test socket having all electrode current (1) (anode) conditions applied and record Ib continuously
for 3 minutes. Ib shall reach 85 percent of the 3 minutes figure within the time indicated.
16. The life-test sample shall consist of 20 tubes per lot and not tube failure shall be permitted. In the event of rejection of the
first sample, a second sample of 40 tubes shall be elected from the lot. Acceptance shall then be based on the second
samples and there shall be zero tube failures.
17. This specification sheet utilizes an accept on zero defect sampling plan in accordance with MIL-PRF-1, table III.
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