MIL-PRF-1/1055F
TABLE I. Testing and inspection - Continued.
1/ Sufficient conduction and convection cooling shall be provided to limit the envelope temperature to the
specified maximum of 175°C under all operating conditions.
2/ Operation at this altitude is possible in a suitably designed circuit.
3/ Modulation essentially negative may be used if the positive peak of the audio frequency envelope does not
exceed 115 percent of the carrier conditions.
4/ This tube operates at frequencies where transit-time effects of the electron current shall be considered. The
principal effects influencing the tube operation are the decrease in power output and operating efficiency with
increase in frequency, and the bombardment and heating of the cathode by electrons from the region of the
grid, which can be sufficiently severe to result in short tube life and erratic operation. Operating frequency,
circuit design and adjustment, grid bias, grid current, average power input and the operating voltage
contribute to some degree to the magnitude of the resulting cathode bombardment. There is a heater voltage
which will maintain the cathode at the correct operating temperature for a set of operating conditions. If the
conditions of operation result in appreciable cathode back-heating. It may be necessary to initiate dynamic
operation of the tube at normal heater voltage, followed by a reduction of heater voltage to the proper value.
A maximum variation of ± 5 percent in heater voltage is recommended where consistent operation and
extended tube life is a factor.
5/ Carrier conditions for use with a maximum modulation factor of 1.0.
6/ Tube shall not be operated for more than 6 microseconds in any 5,000 microsecond interval. Tube shall not
be grid-pulsed beyond the CW ratings.
7/ The regulation or series-anode-supply impedance, or both, shall limit the instantaneous peak current, with
the tube considered as a short circuit, to a maximum of 10 times the specified maximum current rating.
8/ Other tube contact configurations may be used provided the tube contact area remains unchanged and the
socket, jig, or cavity gives equal performance. Mounting of the socket, jig, or cavity may be at the option of
the manufacturer.
9/ Torque test shall be performed as follows:
a.
A torque of 15 inch-pounds shall be applied between the anode and heater terminal No. 1 without
shock. This is not a destructive test.
b.
A torque of 5 inch-pounds shall be applied between heater terminal No. 1 and heater terminal No. 2
without shock. This is not a destructive test.
During the test, the maximum temperature of any part of the envelope shall be limited to 175°C maximum by
10/
conduction or forced convection cooling.
11/
Perform test on 10 tubes selected at random from the first production lot of each calendar year. If one tube
fails, the test shall become part of conformance inspection, part 2. Acceptance shall be based upon accept
on zero defect (c = 0) sampling plan, in accordance with table III of MIL-PRF-1. After three consecutive
successful submissions, the test shall revert to an annual 10-tube test.
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