MIL-PRF-1/1260K
TABLE I. Testing and inspection - Continued.
1/
It is recommended that a heater voltage, as determined from figure 3, be utilized whenever Ip is less than 0.75 A ac. The
heater voltage must be held within ± 5 percent of the values shown on figure 3.
2/
For cold-starting applications, where anode voltage is applied instantaneously, the power-supply filter design shall be such
that the maximum permissible epy is 1,000 v and cannot be attained in less than 0.04 second. It is recommended that the
driver pulse be applied prior to the application of anode voltage.
In pulsed operation, the peak inverse voltage shall not exceed 500 v during the first 25 µs after the pulse.
3/
The value shown is valid only for the following pulse shape: Time of rise = 0.5 µs maximum, grid pulse duration = 2.0 µs
4/
minimum. Impedance of drive circuit = 1,000-ohms maximum.
5/
The rated time jitter of 5 ns is applicable only at peak forward anode voltages in excess of 500 v epy, and with a driver pulse
in excess of 250 v egy. At values of epy less than 500 v or egy less than 250 v, the time jitter maximum is 10 ns.
6/
Under reduced ratings, operating frequencies up to 50 kHz are feasible.
The circuit constants shall be chosen so that at epy = 1.2 kv under resonant charging conditions: dik/dt = 400a/µs minimum,
7/
ib = 20a, tp = 0.50 µs ± 10 percent, prr = 5,000 and Rg1 = 10,000 to 30,000 ohms. The grid pulse characteristics shall be tp =
2.0 µs maximum, tr = 0.5 µs, and driver impedance = 1,000 ohms minimum.
Heater-cathode shorts for 100,000 ohms or less, having a duration of 100 µs or more, are cause for rejection.
8/
9/
Inability to hold off dc anode voltage, when tapped with a cork hammer using 3.0-inch (76 mm) strokes constitutes a failure.
10/
Monitor grid-cathode voltage to indicate short or open when tube is tapped with a cork hammer using 3.0-inch (76 mm)
strokes. Indication of short or open is cause for rejection.
11/
Failure to hold off dc anode voltage during the vibration period shall constitute a failure.
12/
The tube shall operate satisfactorily on pushbutton starting within three attempts when anode voltage is applied in such a
manner as to rise from 0 to 1,000 v within 0.03 second (the filter design shall be such that at least 500 v is reached within
0.015 second). Any tube failing to start within three attempts shall be considered a failure.
13/
No voltages shall be applied to the grid or anode of the tube under test for at least 10 minutes prior to performing this test.
14/
The tube shall operate continuously for 5 minutes without evidence of continuous conduction, anode heating, or loss of
control.
15/
Using a calibrated oscilloscope, adjust epy for a peak cathode current of 20 amperes. Measure the voltage drop between
anode and cathode from the zero reference line to the center of the tube drop porch (see figure 4).
16/
During the interval between 2 minutes and 7 minutes of the tad test, the anode delay time drift relative to the tad value
observed on the anode delay time test, shall not exceed the value specified herein.
17/
Life test shall be operated with the tube in a horizontal position. Operation shall consist of 12 minutes of operation (heater,
trigger, and anode voltage) and 12 minutes off. The application of anode voltage may be delayed a maximum of 60 seconds
after the application of heater voltage. Only anode operating time shall be considered test time. The average life of the
sample shall be not less than 90 percent of the duration of the test.
18/
No defects are allowed.
19/
This test is to be the first test performed at the conclusion of the holding period.
20/
This test shall be performed during the initial production and once each succeeding 12-calendar months in which there is
production. A regular sampling plan shall 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, with an acceptance level of 6.5 (see 21/).
The regular "12-calendar month" sampling plan shall be reinstated after three consecutive samples have been accepted.
21/
This specification sheet uses accept on zero defect sampling plan in accordance with MIL-PRF-1, table III.
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