MIL-PRF-1/1000B
TEST PROCEDURE
Reflection and transmission differences
1. Purpose. The purpose of this test is to measure the reflection and transmission differences.
2. Procedure. The reflection and transmission differences shall be measured, with ignitor currents in the range specified, by
comparing the tube under test (TUT) with a standard dummy at F1, F2, F3, F4, and F5, in a special waveguide bridge circuit. The testing
procedure and equipment used in testing the TUT shall be as follows.
2.1 Tuning. The tuning and low-level acceptance testing of the tube shall be accomplished by comparing the tube with a comparison-
standard dummy (see 2.6), in the waveguide bridge circuit (see 2.5). The TUT and the comparison-standard dummy may be inserted in
opposite branches of the waveguide bridge circuit in the test openings designated 1 and 2.
2.2 Signal. The signal source and difference measuring display shall comprise a continuously-swept oscillator covering the frequency
band from 8,500 to 9,600 MHz, synchronized with a dual-channel oscillographic display (Polarad Model I, or equivalent). This signal
display shall consist of two signals proportional to the magnitude of the vector differences in reflection and transmission between the TUT
and the comparison-standard dummy, as obtained from the detectors designated R and T in the waveguide bridge circuit.
2.3 Maximum difference. This specification specifies the maximum magnitude of the vector differences in low-level reflection and
transmission between each tube and the comparison-standard dummy. The values of these vector differences are as follows.
a. 2 dB SWR in reflection.
b. 5 degrees in transmission.
2.4 Acceptance limits. The acceptance limits specified in the specification sheet and covered above in 2.3 shall be set by comparing
each of the differential standards described below in 2.7.1 and 2.7.2 with the precision guide section described below in 2.7.3. The
precision guide section shall be inserted in one of the test openings and the differential standards inserted successively in the other test
opening shown on figure 3. The magnitude of each of the resulting display deflections shall be adjusted to correspond with limit lines on
the scope face by adjusting the gain controls of each display circuit. The setting of waveguide attenuator P1 shall be determined
experimentally beforehand by adjusting it for the maximum amount of attenuation which permits both steps of the calibration procedure
described above to be performed without readjusting the attenuator or without excessive noise on the display; a minimum attenuation of 6
dB is required to pad the oscillator from the bridge circuit.
2.5 Waveguide bridge circuit. The waveguide bridge circuit is shown on figure 3, and shall meet the following requirements.
2.5.1 Mechanical. The mechanical requirements of the waveguide bridge circuit are as follows:
a. The waveguide parts shall have the inner dimensions of M85/1-073-120 waveguide (1.497 x 1.122 inches) (38.02 x 28.50
mm).
b. Both waveguides at the test openings 1 and 2 shall be terminated by M3922/59-007 flanges.
c. Each pair of flanges at test openings 1 and 2 shall be fastened rigidly together to maintain the waveguides parallel and
aligned, and the openings 2.000 ± .002 inches (50.80 ± 0.05 mm) long.
d. Test parts in openings 1 and 2 shall be held to flanges nearest signal input by even pressure applied at four points at opposite
end.
2.5.2 Electrical. The electrical requirements of the waveguide bridge circuit are as follows:
a. Over the band from 8,500 to 9,600 MHz, the reflection measured in either direction at the planes shall be as indicated below:
Plane
Maximum SWR
less than 3 dB
A
less than 2 dB
B
C
less than 3 dB
D
less than 2 dB
5
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business