MIL-PRF-1/1203K
TABLE I. Testing and inspection - Continued.
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Grid recovery. Test shall be performed as follows:
a. With 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. With application of pulse, measure undershoot (Ćib) and change in average current (ĆIb).
6/
Prior to this test, tubes shall be preheated for a minimum of 5 minutes at the conditions indicated below. The 3-minute test is not
permitted. Test within 3 seconds after preheating.
Ef
Ecc
Ebb
Rk
Rg
Rp
V
V dc
V dc
Ohms
Meg
Meg
7.0
0
250
82
0.1
0.018
7/
Envelope strain procedure. Tubes shall be tested as specified in method 2126, except that they shall be immersed in water at not
more than 5°C for 15 seconds and immediately thereafter subjected to the standard temperature cycle specified in method 2126.
The criteria for air leaks shall be heater current of 300 mA, or more.
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/
Intermittent life. The specified life-test end points shall be applied to both the intermittent life-test (1) and (2) test samples with the
exception of noise figure and power gain measurements, which shall be performed on the intermittent life-test (1) samples only.
10/
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.
Sweep-frequency vibration. Test shall be performed as follows:
11/
a. The frequency shall be increased from 100 to 5,000 Hz with approximately logarithmic progression in 3 ± 1 minutes. The
return sweep (5,000 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 heater contacts.
c. The value of alternating voltage, Ep, produced across the resistor, Rp, as a result of vibration shall be measured with a suitable
device having a response to the rms value of a sine wave of voltage to within ± 0.5 dB of the response at 100 Hz over the
frequency range of 50 to 5,000 Hz and having a frequency cutoff such that the response is down a minimum of 12 dB at
10,000 Hz. The meter shall have a dynamic response characteristic equivalent to, or faster than, a VU meter (operated in
accordance with Acoustical Society of America Standards No. C16.5-1954).
Sweep-frequency vibration fatigue. Test shall be performed as specified in method 1031, except that the tubes shall be vibrated
12/
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.
13/
This test shall be performed during the initial production and once each succeeding 12-calendar months in which there is
production. A regular double sampling plan shall be used, with the first sample of three tubes with an acceptance number of zero,
and a second sample of three tubes with a combined acceptance number of one. 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. Acceptance shall be based upon accept on zero
(c = 0) sampling plan in accordance with Table III of MIL-PRF-1. The regular "12-calendar month" double sampling plan shall be
reinstated after three consecutive samples have been accepted.
14/
Acceptance shall be based upon accept on zero (c = 0), in accordance with Table III of MIL-PRF-1.
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