MIL-DTL-87104C
4.6.2.1.3.2 Test method I: Slotted line. When using the slotted line method, measurements shall be made at
frequency increments not greater than 0.04 GHz below 0.50 GHz, 0.10 GHz between 0.50 and 5 GHz, 0.20 GHz
between 5 and 10 GHz, and 0.40 GHz above 10 GHz. The measured data shall be recorded on a tabulation sheet or
plotted on 8- by 10-inch graph paper.
4.6.2.1.3.3 Test method 2: Reflectometer. The reflectometer method shall be accomplished as specified in
procedure I (see 4.6.2.1.1.3).
4.6.2.1.3.4 Test method 3: Swept slotted line. The swept slotted line method shall be accomplished as specified
in procedure I (see 4.6.2.1.1.4), except the permanent record may be an X-Y recording or a photographic record
taken from an oscilloscope display. (Tabulation is not required.) (On photograph tabulate only the ends of the band).
4.6.2.1.3.5 Other test methods. Other test methods may be used when approved by the cognizant engineering
activity.
4.6.2.1.3.6 Accept-reject criteria (procedure III). If the VSWR of the equipment under test exceeds the value
specified in the applicable detail specification, the equipment shall be considered to have failed the VSWR production
test.
4.6.2.2 Impedance test (see 3.5.1.3). The impedance test shall determine the characteristic impedance and the
impedance uniformity (peak-to-peak variation) of the coaxial assembly. Variations in dimensions, dielectric material,
or manufacturing procedures can produce changes in the characteristic impedance or impedance uniformity. These
changes generate reflections and degrade the electrical performance of the coaxial assembly.
4.6.2.2.1 Test setup.
4.6.2.2.1.1 Test equipment. The impedance of the test sample shall be determined by means of a Time Domain
Reflectometer which has a system pulse rise time not in excess of 150 picoseconds and resolution of 0.1 ohm
throughout the length of the test sample.
4.6.2.2.1.2 Test conditions. This test shall be conducted under room ambient conditions (see 4.3.1.1) and as
specified herein.
4.6.2.2.2 Procedure. The impedance test shall be conducted as follows:
Insert an air line with a calibration of 50 ± 0.1 ohm in series with the test sample between the test
a.
equipment and the input end of the test sample.
b.
Establish a 50-ohm reference line on the graph paper.
c.
Record the impedance of the test sample on calibrated rectangular coordinates using 8- by 10-inch graph
paper (10 by 10 to the inch) and a scan rate of 20 feet of cable per minute. Identify the plots of the air line
reference, the input interface, the entire length of the test sample, the output interface and any required
terminating networks.
d.
Examine the permanent record to ascertain the maximum and minimum points of the impedance plot and
identify the value of these points.
4.6.2.2.3 Accept-reject criteria(see 3.5.1.3). If the impedance of the test sample is different than 50 ± 1 ohm, the
sample shall be considered to have failed the impedance test.
4.6.2.3 RF insertion loss tests (see 3.5.1.4). The test procedures specified herein shall determine the RF insertion
loss characteristics of the assembly.
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