MIL-PRF-1/952H
TABLE I. Testing and Inspection - Continued
Acceptance
Limits
Requirement or Test
Method
Conditions
Symbol
Unit
level
Min
Max
note 9
Conformance inspection, part
3 Continued
Total grid current
1266
---
Ic1
0
-1.0
uA dc
Heater current
1301
---
If
275
333
mA
Change in transcon-
1306
---
%Sm
---
25
%
ductance (1) of
t
individual tubes
%Sm
Transconductance (2)
1306
---
---
20
%
Ef
Heater-cathode leakage
---
Ihk
---
20
uA dc
MegΩ
Insulation of electrodes
---
R
50
---
Ef = 6.9 V
Cathode interface life
1511
---
Ri
---
50
ohms
See note 10
NOTES:
1.
See "Reduced pressure (altitude) rating" and altitude, maximum peak voltage.
2.
Tie grid 3 co negative terminal of cathode resistor.
3.
This test shall be performed at the conclusion of the holding period.
4.
Prior to this test, tubes shall be preheated for a minimum of 5 minutes at the conditions indicated below. The 3-minute
test shall not be 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
Ec1
Ec2
Ec3
Eb
Rh
Rg1
MegΩ
V
V dc
V dc
V dc
V dc
Ohms
7.5
0
150
0
300
80
0.5
A grid resistor of 0.1 MegΩ shall be added; however, this resistor shall not be used when a thyatron-type short indicator is
5.
employed.
6.
This test shall be performed yearly. An accept on zero defect sampling plan 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,
acceptance level 6.5 (see 10/). The yearly sampling plan may be reinstated after three consecutive samples have been
accepted.
7.
Acceptance sampling procedure shall be in accordance with "base-strain test, miniature sampling" (method 1121), except
that data covered in "Acceptance and rejection criteria" shall be modified as follows:
(a)
Accepted if no defectives for class `A', `B', or `C' defects, respectively (see method 1121), or if no defectives are
found in the sample.
(b)
Rejected if any defectives for class `A', `B', or `C'defects, respectively, or if any defectives are found in the sample..
8.
Envelope temperature (TE) requirements, when measured in accordance with the temperature by conduction-band
measurement (method 1226), will be satisfied if a tube 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.
9.
This specification sheet utilizes an accept on zero defect sampling plan in accordance with MIL-PRF-1, table III.
10. The life-test sample shall consist of the lesser of 20 tubes or 10% of lot size and no failures shall be permitted. In the
event of failure of the first sample, a second sample of the lesser of 20 tubes or 10% of lot size shall be selected from the
lot. Acceptance shall then be based on the second samples, and no failures shall be permitted.
4
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