MIL-PRF-1/1099H
TABLE I. Group A inspection.
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│MIL-STD-|
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│ 1311 │
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Limits
│ Inspection
│Method │ Conditions
│ Acceptance
│ Symbol
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│ Unit
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│ level 9/
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│ min
│ max
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│ Conformance
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│ inspection, part 3
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│ -Continued
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│Life test (2) 6/
│ ----
│Life test (1); operation (2)
│ ----
│ ----
│ ----
│ ----
│ ----
│
│
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│Zg = 250 Ω; t = 500 hours
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│Life test (1) and (2)
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│ endpoints:
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│ Operation (1)
│ 3246 │
│ ----
│ egy
│ ----
│ 650
│v
│
│ DC anode voltage
│ 3247 │egy = 500 v
│ ----
│ Ebb
│ ----
│4500
│ Vdc
│
│
│
│
│
│
│
│
│
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for conduction
│ Time Jitter
│ 3261 │egy = 500 v; Zg = 250 Ω
│ ----
│ tj
│ ----
│ 0.005
│ µs
│
│
│
│
│
│
│
│
│
│
│Operation at elevated
│ 3246 │TA = 75ºC; t = 5 hours
│ ----
│ egy
│ ----
│ 550
│v
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│ ambient temperature
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1/ 2/
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│Life test (3) 1/ 3/
│ ----
│t = 500 hours
│ ----
│ ----
│ ----
│ ----
│ ----
│
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│Life test (3)
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│ endpoints:
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│ Operation (1)
│ 3246 │
│ ----
│ egy
│ ----
│ 675
│v
│
│ DC anode voltage
│ 3247 │
│ ----
│ Ebb
│ ----
│4500
│ Vdc
│
│
│
│
│
│
│
│
│
│
for conduction
│ Time Jitter
│ 3261 │egy = 650 v
│ ----
│ tj
│ ----
│ 0.01
│ µs
│
1/ The circuit constants shall be chosen so that at epy = 25.0 kv under charging conditions: dik/dt = 5,000 a/µs minimum; ib =
1,000 a minimum; tp = 2.5 ± 0.25µs; prr = 500 minimum. The grid pulse characteristics shall be: tp = 2.0 µ maximum; tr =
0.35 µs minimum; internal impedance of driver = 250 ohms minimum.
2/ This test shall be conducted for a total of 5 consecutive hours with no more than three kickouts and with no evidence of anode
heating. The tube shall be started at Eres = 105 percent of the inscribed value and operate at this value for 4 hours. At the
start of the fifth hour and while the tube is still operating, the reservoir voltage shall be lowered to 95 percent of the inscribed
value and remain there for the final 1 hour of operation.
3/ The life test shall be intermittent, with the tube operating approximately half the total elapsed time, and held without reservoir
voltage or cathode-heater voltage approximately half the total time. The tube shall make a minimum of four starts during
each 24-hour period. The life-test duration is measured in operating hours. Failure of the tube to operate following the
minimum allowable cathode and reservoir heater warmup time constitutes failure of the test.
4/ The tube shall operate satisfactorily on push-button starting within three attempts when the anode voltage (epy) is applied to
the tube under test in such a manner as to rise from 0 to 18 kv 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.
5/ The anode circuit constants shall be so chosen that a resonant charging conditions; epy = 15 kv; ib = 500 a minimum; dik/dt =
5,000 a/µs minimum. Output pulse; tp = 1.3 µs ±10 percent; prr = 1,500 minimum; epx = 5.0 kv. Grid pulse the same as
note 1. Adjust reservoir voltage to optimum value for these test conditions. The tube shall operate continuously for 20
minutes without continuous conduction.
6/ The optimum reservoir voltage for operation in accordance with operation (2) conditions shall be so determined that the tube
shall operate at 95 to 105 percent of the established reservoir voltage for these conditions.
7/ 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 -tad measurement is the numerical difference
between the 2-minute and 4-minute, or 2-minute and 30-minute anode delay time readings, whichever is greater.
8/ The tj shall be not greater than the amount specified after 120 seconds of anode operation.
9/ This specification sheet uses accept on zero defect sampling in accordance with MIL-PRF-1, table III.
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