MIL-PRF-32517
d. Workmanship: Visually examine with a 3X microscope for blistering, pitting, or
peeling of plating, cracks, and other defects which may affect serviceability.
TABLE XI. Classification of defects.
Examination or test
Major
Minor
Workmanship and markings
X
Missing components
X
All other criteria
X
4.6 Test methods.
4.6.1 Characteristic impedance (see 3.4.1).
4.6.1.1 Specimen. The specimen shall be not less than 10 feet.
4.6.1.2 Procedure. The specimen shall be prepared for testing by assembling appropriate
connections to the cable ends. The equipment shall include a Time Domain Reflectometer
(TDR). The rise time of the TDR shall be 150 picoseconds or less, and the vertical sensitivity of
the system shall provide for a minimum resolution of one major scale division. Matched
impedance splice measurement shall be taken by gating within 1 nanosecond on each side of the
splice.
The matched impedance splice assembly shall then be turned end-to-end and the measurement
repeated. For cables of other than 50 and 75 ohms characteristic impedance, the characteristic
impedance may be determined by calculation from the capacitance measurement determined and
the velocity of propagation measurement determined, using the following formula:
Zo = Velocity of propagation (%) X Capacitance (pF/ft)
4.6.2 Insertion loss. The insertion loss shall be determined in accordance with EIA-364-
101, Method A. A vector network analyzer is preferred. For cable impedances other than 50
ohms, minimum loss impedance matching pads or a mechanical adapter with adapter
characteristic embedding may be used with open/short/load calibration standards for the cable
impedance value (see 3.4.2 and 6.5).
4.6.3 Return loss. The return loss shall be measured in accordance with EIA-364-108,
frequency domain method. For cable impedances other than 50 ohms, minimum loss impedance
matching pads or a mechanical adapter with adapter characteristic embedding may be used with
open/short/load calibration standards for the cable impedance value. SWR is mathematically
calculated from the return loss (see 3.4.3).
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