MIL-PRF-1/1755B
TABLE I. Testing and inspection - Continued.
21/ The radio frequency bandwidth and side lobes shall be within the limits specified with a VSWR of 1.5:1 minimum is introduced in
the load and the phase is adjusted at the start of each measurement to produce maximum degradation. A satisfactory spectrum
is one whose slope does not change sign more than once for power levels greater than 6 dB below its peak.
22/ The seal formed by clamping the tube mounting plate against a suitable tube test fixture shall be hermetically tight for 1 minute
minimum with the specified air pressure applied so as to surround the entire input bushing below the mounting plate.
23/ The seal formed by clamping the tube output flange against a suitable tube test fixture shall be hermetically tight for 1 minute
minimum with the specified air pressure applied internally to the test fixture.
24/ The tube shall be coupled directly to M3922/59-007 choke flange modified so that mounting holes provide clearance for No. 8
bolts.
25/ The modulator shall be such that energy per pulse delivered to the tube, if arcing occurs, shall not greatly exceed the normal
energy per pulse. The tube heater shall be protected against arcing by use of a connector that places a minimum of 4,000 pF
across the heater directly at the input terminals.
26/ At the completion of this test, the tube shall meet the power output and pulse voltage requirements of quality conformance
inspection, part 1.
27/ The pushing factor shall be measure in steps of at least 4 amperes each and no value shall exceed the limits specified herein.
The peak current through the tube shall alternately be the limits as specified under this test condition. These tests shall be run
to exclude the affects of thermal drift and frequency instability not due to pushing.
28/ In addition to regular markings the tuner dial settings for the following frequencies shall be marked on the tube. The accuracy of
these settings shall be ±5 MHz at the start of life under conditions of test condition (2) with the anode temperature approximately
80șC as measured at the point specified on figure 1 when tuning is performed in the order of increasing the frequency.
Frequency code
Dial setting
F1
----
F2
----
F3
----
29/ Starting at F1 and increasing to F3, then decreasing to F1, the frequency of the tube will be changed in 200 MHz increments
(approximately) after each 50 hours (approximately) of high-voltage operation. The duration of the switching interval between
test conditions 1 and 2 shall not exceed 5 seconds. The following cycle shall be used for life test:
Condition
Duration (minutes)
Standby
2.5
Test condition 1 (see note 5)
25.0
Test condition 2 (see note 5)
25.0
Off
7.5
30/ Service-life guarantee is acceptable in lieu of life test if specifically authorized by contract.
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