MIL-PRF-1/1612C
NOTES:
1/ Instantaneous starting is permissible. The maximum permissible instantaneously applied epy shall be 16 kv and
shall not be attained in less than 0.04 second. Epy may then be raised to full rating.
2/ In pulsed operation, the peak inverse voltage, exclusive of a spike of 0.05 µs maximum duration, shall not
exceed 5 kv during the first 25 µs following the anode pulse.
3/ The driver pulse, measured at tube socket with thyratron grid disconnected: amplitude per ratings; tr = 0.35 µs
(max); tp = 2 µs (min); Zg = 250 to 500 ohms. At -55°C, 250 V (min) is required.
4/ For hydrogen thyratron applications Ip shall be computed as the square root of the product of Ib x ib.
5/ A cooling air blast of 10 cfm may be directed into the anode cup when operating at maximum anode dissipation.
6/ The optimum heater voltages for operation in accordance with Operation (1) conditions is 6.3 V ac and shall be
held to within ±7.5 percent. Applications involving other operating conditions may necessitate redetermination of
the optimum reservoir voltage.
7/ Appreciably less jitter than 0.005 µs can be realized: If the anode voltage is 8 kv or more; the grid drive amplitude
is near the maximum and the grid drive impedance is near minimum.
8/ There shall be no pronounced resonance in the range from 10 to 250 Hz when the tube is mounted by the
cathode flange.
9/ The tube shall be tested in the test circuit shown on figure 2. Tests performed at repetition rates less than the
resonant rate shall be made with a hold-off diode in the charging circuit. The circuit constants shall be chosen
under resonant charging conditions so that:
epy = 20 kv; ib = 200 a (min); dik = 2,000 a/µs (min); tp = 0.6 µs ± 10 percent; prr = 2,500 pps (min).
dt
WARNING: These conditions are specified only for the purpose of determining circuit constants. The actual
operating voltage and repetition rates for each test are specified in the conventional manner under the particular
conditions or under the general test conditions, as the case may be.
Grid pulse as measured at tube socket with thyratron grid disconnected shall have the following characteristics: tr
= 0.35 µs (min); tp = 2 µs (max). The internal impedance of driver shall be 500 ohms minimum.
10/ This test shall be the first test performed after the holding period. The tube shall operate satisfactorily on push-
button starting within three attempts when the anode voltage (epy) is applied to the tube under test in such a
manner as to rise from 0 to 16 kv minimum within 0.03 second. (The filter in the rectifier shall be designed so
that the epy reaches at least 8 kv within 0.015 second.) The intervals between successive attempts to
instantaneously start the tube shall be not less than 10 nor more than 30 seconds. Any tube failing to start within
three attempts shall be considered a failure.
11/ This test shall be conducted within 60 seconds of the Operation (1) test.
12/ The tube shall operate continuously for 10 minutes.
13/ There shall be no evidence of arcback or detrimental anode heating during this test.
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