MIL-DTL-9177C
signal power shall be indicated by a tunable radio frequency field intensity meter isolated from the test
circuit by a 3 to 10 dB pad. Care shall be taken to ensure that the signal is a result of RFI leakage from
within the mated connector and not due to a faulty termination inside the fixture. All terminations inside
the fixture, whether to the RFI shells or between internal conductors, shall have a leakage at least 10 dB
less than the test requirements. The signal source shall be set to the desired frequency. The signal shall
be fed through a 3 to 10 dB isolation pad to a parallel circuit consisting of a coaxial switch (DPDT) so
connected that the signal can be manually or electrically fed alternately to the fixture and to a variable 100
dB reference attenuator. The attenuator shall be adjustable in 1 dB steps and calibrated to ± 3 dB.
a. The inserts may be removed from the connectors under test or the contacts removed and a hole
drilled through the inserts to accommodate a center conductor of suitable geometry to provide a
good 50-ohm impedance match with the inside diameter of the mated connector shells. Tapered
transitions may be used to provide a means of changing diameters without introducing significant
discontinuities in the line. The maximum VSWR in the inner coaxial line shall be 1.5 dB. The outer
shall of the test fixture shall be so constructed as to provide a good 50-ohm impedance match with
the outside diameter of the mated connector shells. The maximum VSWR of the outer coaxial line
shall be 1.5 dB.
b. A sliding circumferential short shall be positioned behind the connector on the single input end of
the fixture to provide for tuning the outer coaxial line for maximum output at each test frequency.
The allowable travel of this short shall be greater than 1/2 wave length at the lowest test frequency
of 1.5 meters minimum for 100 MHz. The inner coaxial line shall be terminated in a fixed 50-ohm
load impedance behind the connector at the output end of the fixture.
c. The connectors used to couple together the various elements of the test system shall be of a low-
leakage type which have a nominal impedance of 50 ohms, a VSWR of less than 1.5 dB, and a
minimum leakage attenuation of 100 dB. The output impedance of the signal source and the input
impedance of the detector shall be nominally 50 ohms with a maximum VSWR of 1.5 dB. The input
and output VSWR of the standard attenuator shall be less than 1.5 in the 20 to 100 dB range.
d. The relative signal level in the variable attenuator shall be equal to the signal level through the
leakage fixture by adjusting the attenuator. The signal loss in the fixture can then be read from the
setting on the variable attenuator.
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