MIL-PRF-1/1729E
TABLE I. Testing and inspection - Continued.
9/
After heater warmup, and using the circuit of figure 2, the anode voltage shall be raised slowly to 10 kV dc. Intermittent arcing
may occur as the anode voltage is increased, but more than 5 arcs shall be cause for rejection. The voltage shall be held at
the 10 kV dc level for 1 minute; if any arcs occur during this time, or Ib exceeds the specified limit of 1.0 mA dc, the tube shall
be rejected. If any arcs occur during this period the TUT shall be held at the 10 kV dc level for an additional 2 minutes and if
no additional arc occurs (and Ib does not exceed the specified limit of 1.0 mA dc), then the TUT shall be accepted.
10/
At zero hours of life test, measure and record Cgp, and establish the drive conditions necessary to obtain a peak anode
current (ib) of 3 amps (minimum) with an anode voltage of 2.0 kV dc and a bias of -40 V dc. The pulse width of the modulator
shall be 2 µs (minimum) and the duty cycle shall be 0.0025 (maximum). At the conclusion of the life test, measure Cgp and
calculate ĆCgp, and with the drive level determined at zero hours, check the peak anode current and calculate Ćib.
11/
Where emphasis is placed on long and reliable life, the filament voltage can safely be lowered to 6.0 volts, provided the line
voltage is regulated better than ±2 percent.
12/
The tube shall be suitably mounted (for example, epoxy encapsulated) and vibrated with simple harmonic motion. The peak
acceleration over the frequency range shall be within ±20 percent of the reference acceleration at 100 Hz. The frequency
shall vary from 55 to 500 Hz and return to 55 Hz with approximately logarithmic progression and shall require from 4 to 6
minutes to traverse the range. Each tube shall be vibrated for 30 minutes in the X and Y axes, except that if the cumulative
result of tests on 50 or more tubes shows more than 75 percent of the tubes have higher output voltages in one position,
subsequent measurements need to be taken only in the position giving the higher reading. The voltages specified shall be
applied during vibration. The value of the alternating voltage, Ep, produced across the resistor, Rp, as a result of vibration
shall be measured with a device having the ability to measure, with an error of less than 10 percent, the rms value of a sine
wave of voltage at all frequencies from 20 to 20,000 Hz.
13/
This test shall be performed during the initial production and once each succeeding 12-calendar month period in which there
is production.
14/
The tube shall be suitably mounted (for example, epoxy encapsulation). Each tube shall be subjected to a total of 15 shocks;
5 shocks in each plane +X, +Z, and -Z in any sequence.
15/
Voltage shall be 60 Hz ac applied between the anode and grid. No other voltages shall be applied. There shall be no
evidence of failure as indicated by arc-over. Perform test on 10 tubes selected from the first production lot of each year. If
any tube fails, the test shall become part of conformance inspection, part 2. After three consecutive successful submissions,
the test shall revert to a 10-tube annual test. This is not a destructive test.
16/
Test shall be conducted in a cavity assembly in accordance with the following Hazeltine Corporation drawings, or equivalent:
114329-5
Final output cavity assembly
114277-7
RF filter assembly
114612
Connector (matching stub)
330620
Power divider (SMA"T")
A 0.47 µF cathode bypass capacitor shall be employed.
(Copies of the above drawings may be obtained from Hazeltine Corporation, Greenlawn, NY 11740 at no cost.)
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