MIL-PRF-1/1657E
TABLE I. Testing and inspection - Continued.
4/
This test shall be performed in amplifier cavity Amerac Model No. 1244-1, or equivalent. Test
frequency shall be 550 10 MHz. Input = 0.2 W. When the amplifier has been tuned, adjust
Ec for Ib = 20 mA dc.
5/
Transconductance (2) is the percent change in transconductance (1) of an individual tube
resulting from a change in Ef.
6/
Tube supported at cathode and anode terminals with the grid disk centered. The supports
shall be placed 0.938 0.016 inch (23.83 0.41 mm) apart. Apply force to the grid disk
without shock, perpendicular to the axis of the tube. Inspect for defects described in MIL-
PRF-1, appendix D, Vacuum Seal (metal-to-glass) defect classification.
7/
Electrical rejects may be used.
8/
Whenever Ec is not specified on any test, the grid shall be grounded directly or through a grid
resistor (if specified) except when related MIL-STD-1311 test methods imply grid variance to
accomplish this test.
9/
The no-load to a steady-state full load of the heater voltage supply shall be not more than 3
percent. A failure or defect shall consist of an open heater, open cathode circuit, heater
cathode short, or heater cathode leakage in excess of the specified heater cycling life-test
end-point limit.
10/
Test shall be performed in amplifier cavity Amerac Model No. 1244-1, or equivalent. Test
frequency shall be 550 10 MHz. Adjust Rk for Ik = 25 mA dc and Rg for Ig = 6 mA dc.
11/
Cycle Ef only, 110 minutes "on", 10 minutes "off".
12/
Test shall be performed on a group D basis every 90 days with the lot consisting of the current
month and two subsequent months. Failure of any tube shall revert back to group D monthly
lot sampling. After three consecutive successful lot submissions have been completed, the
test may revert to the quarterly basis.
13/
Test shall be performed in accordance with method 1521 and MIL-PRF-1 every 90 days.
Failure of any tube shall revert back to MIL-PRF-1 monthly lot sampling. After three
consecutive successful submissions have been completed, the test shall revert to the
quarterly basis.
14/
A complete cycle is made in a 6-minute period as follows: 3 minutes on, 3 minutes off. This
is a destructive test. Mechanical or electrical rejects may be used.
15/
Tubes meeting the initial test requirements after stability and survival-rate life tests shall be
accepted under this specification.
16/
Subject tubes to shock in axes X, Y, and Z for a total of 15 blows, five blows in each axis.
17/
Vibrate in axes X and Y only for a total of 64 hours, 32 hours in each axis.
18/
This specification sheet uses accept on zero defect sampling in accordance with MIL-PRF-1,
table III.
19/
Use basic test method 2126 (for receiving tubes) for seal strain test of this ceramic tube type.
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