MIL-PRF-1/1371J
TABLE I. Testing and inspection - Continued.
1/
An MT-4 mounting assembly (or equivalent) shall be provided as an integral part of each tube. (See figures 2 and 3 for
reference only.)
2/
Instantaneous starting is permissible. The maximum permissible instantaneously applied epy is 18.0 kv and shall be attained
in not less than 0.04 second. The epy may then be raised to full rating.
In pulsed operation, the peak inverse voltage exclusive of a spike of 0.05 µs maximum duration, shall not exceed 5.0 kv
3/
during the first 25 µs following the anode pulse.
The driver pulse, measured at tube socket with thyratron grid disconnected: tr = 0.35 µs maximum, grid pulse duration = 2.0
4/
µs minimum. Impedance of drive circuit 50 to 400 ohms.
5/
A maximum backswing voltage of 650 volts on the grid of the thyratron is permissible immediately after the trigger pulse.
There shall be no forced-air cooling which will reduce T (anode) or TE below 150°C. At average current levels exceeding 1.5
6/
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amperes when the Pb factor exceeds 10 x 10 , cooling of the tube is necessary by means of an anode radiator, forced air, or
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both. Radiator design for operation at Ib = 2.0 A dc and Pb = 20 x 10 shall be such that the center of the upper radiator
surface shall not exceed 200°C under operation. A cooling airblast of 10 cfm may be directed into the anode cup.
7/
The circuit constants shall be chosen under resonant charging conditions so that: epy = 25 kv; ib = 1,000 a minimum; dik/dt =
5,000 a/µs minimum; tp = 2.5 ± 0.25 µs; prr = 500 minimum. Grid pulse shall have the following characteristics: tr = 0.35 µs
minimum, tp = 2.0 µs maximum, Zs = 50 to 400 ohms.
8/
The tube shall operate satisfactorily on pushbutton starting within three attempts when the epy is applied to the tube under
test in such a manner as to rise from 0 to 18 kv minimum within 0.03 second. The filter in the rectifier shall be designed so
that the epy reaches at least 9 kv within 0.015 second.) Any tube failing to start within three attempts will be considered a
failure.
9/
The tube shall operate continuously for 30 minutes without evidence of arc-back, with not more than three kickouts during the
first minute of operation.
Reduce the ambient temperature to -55°C in not less than 30 minutes. After 15 minutes soaking, tubes shall perform to
10/
operation (1) conditions, except Ef = Eres = 6.3 V.
11/
This test shall be performed simultaneously with the operation (1) test. An anode delay time measurement shall be made at
the end of 2 minutes, 4 minutes, and 30 minutes of the operation (1) test. The Ćtad measurement is the numerical difference
between the 2-minute and 4-minute, or 2-minute and 30-minute tad readings, whichever is greater.
12/
The tube shall be tested by applying a peak forward anode voltage not to exceed that specified in the test conditions for the
time jitter test immediately after the tk. The tj shall be not greater than the amount specified after 120 seconds of operation.
The anode circuit constant shall be so chosen that the epy = 20 kv; ib = 667a minimum; dik/dt = 5,000 a/µs minimum; tp = 1.0
13/
µs ± 10 percent; prr = 1,500 minimum; grid pulse same as 7/. Tube shall operate for 20 minutes without continuous
conduction.
During every 100 ± 24 hours of life-test operation, the life test shall be shut off for a minimum of 60 minutes, and then checked
14/
for life-test end points.
15/
Where production is less than 50 tubes per month, life test (1) will be performed alternately with life test (2) on a monthly
basis. Sample size under these conditions shall total one tube per month.
16/
Tube must operate satisfactorily at the specified ambient temperature at operation (1) condition for a total of 5 consecutive
hours with no more than three kickouts and with no evidence of detrimental anode heating. The tube shall be started with Ef
= Eres = 6.8 V ac and operate at this value for 4 hours. At the start of the fifth hour, and while the tube is still operating, the
filament voltage shall be lowered to Ef = Eres = 5.8 V ac and remain there for the final one hour of operation.
17/
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 18/). The "12-calendar month" sampling plan shall be reinstated after three consecutive samples have been accepted.
18/
This specification sheet uses accept on zero defect sampling in accordance with MIL-PRF-1, table III.
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