MIL-PRF-1/852E
TABLE I. Testing and conditions - Continued.
Limits
MIL-STD-
1311
Requirement or test
Notes
Conditions
Symbol
Unit
Min
Max
method
Conformance inspection,
part 3 - Continued.
Intermittent life-test end points (500
hours):
Total grid current
1266
ľAdc
Ic1
0
-6.0
Heater current
1301
mA
If
800
1,010
ĆPo
Power oscillation (Ef = 5.7 V)
1236
%
---
15
Ef
ĆPo
Power oscillation (change in
1236
%
---
20
individual tubes)
t
Power oscillation (overage change)
1236
%
Avg
---
15
ĆPo
t
Heater-cathode leakage
1336
ľAdc
Ihk
---
150
MegΩ
Insulation of electrodes
1211
R
25
---
Total defectives
---
---
---
---
---
Intermittent life-test end points (1,000
---
hours):
Total grid current
1266
ľAcc
Ic1
0
-6.0
Heater current
1301
mA
If
800
1,010
ĆPo
Power oscillation (change in
1236
%
---
25
individual tubes)
t
Power oscillation (average change)
1236
%
Avg
---
20
,ĆPo
t
150
Heater-cathode leakage
1336
ľAdc
Ihk
---
MegΩ
---
Insulation of electrodes
1211
R
25
---
Total defectives
---
---
---
---
NOTES:
1.
This test shall be performed at the conclusion of the holding period.
2.
Prior to this test, the tubes shall be preheated a minimum of 5 minutes at the conditions indicated below. The 3-minute test
is not permitted. Test at specified conditions within 3 seconds after preheating. Grid emission shall be the last test
performed on the sample selected for the grid-emission test.
Ef
Rg1
Ec2
Ec1
Eb
V dc V dc V dc Meg Ω
V
0.01
300
-29
600
7.5
3.
Envelope-temperature (TE) requirements, when measured in accordance with the temperature by conduction-band
measurement (method 1226), will be satisfied if a TUT having bogey Ib (ą5 percent) under normal test conditions, is
determined to operate at or above minimum specified temperature at any position in the life-test rack.
4.
The test duration shall be of sufficient length to obtain a stabilized negative Isc2 value. Adjust Ec1 (0 to 6 V dc) to give Pg2
= 5 W. Pg2 shall be calculated as 2.48 times the product of the rectified current and rectified voltage. A protective resistor
of 15,000 ohms shall be placed in series with the primary emission current meter.
5.
This test shall be conducted on the initial lot and thereafter on a lot approximately every 12 months. When one lot has
passed, the 12-month rule shall apply. In the event of a lot failure, the lot shall be rejected and the succeeding lots shall be
subjected to this test until a lot passes. ANSI/ASQ Z1.4, sample size code letter E, shall apply.
6.
A grid resistor of 0.1 megohm shall be added; however, this resistor shall not be used when a thyratron-type short indicator
is employed.
7.
The life-test sample shall consist of 20 tubes per lot and not more than 1 tube failure shall be permitted. In the event of
rejection of the first sample, due to failure of more than 1 tube, a second sample of 40 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 three.
8. This specification sheet utilizes accept on zero defect sampling plan in accordance with MIL-PRF-1, table III.
4
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