MIL-DTL-87104C
6.3 First article inspection. When a first article inspection is required, the item will be tested and should be
representative of the product to be produced for delivery on the contract or purchase order. Information pertaining to
first article inspection and approval of products covered by this specification should be obtained from the acquiring
activity.
6.4 Definitions.
6.4.1 Test discrepancy. Test discrepancy should be construed to be a condition whereby the equipment fails the
accept-reject criteria for a given test due to accidental damage, documentation error, installation error,
instrumentation malfunction, or failure of the test equipment or facility.
6.4.2 Damage, deterioration, and degradation of performance.
6.4.2.1 Damage: Damage must be construed to include such items as: Cracks or fractures of external or internal
structure, irreversible strain or deformation of the structure, fatigue embrittlement of any component, damaged
threads, hairline cracks, cracks or flaws in epoxied or soldered joints, or change in tolerance limits of any internal or
external components beyond specified tolerance limits. If the equipment cannot be completely examined both
internally and externally, it will be necessary to accomplish the examination by radiographic means.
6.4.2.2 Deterioration: Deterioration must be construed to include such items as: Discoloration as would result
from inadequate finish, corrosion, fraying, plating or paint blisters, pitting or peeling, warped or bent parts, excessive
wear, fungus growth, and evidence of moisture inside the equipment.
6.4.2.3 Degradation of performance. Degradation of performance must be construed to include any condition that
results in the loss of performance beyond specification limits.
6.4.3 Band of doubt: A VSWR value must be considered to be in the band of doubt if the measured VSWR = The
maximum allowable VSWR +0.08* (the maximum VSWR = 1). If the VSWR values fall within the band of doubt, a
frequency band of ± 10 percent must be investigated about the point. (*0.10 for frequencies above 12.0 GHz.)
6.4.4 Insertion loss: The insertion loss must be defined as the ratio of the power (P1) absorbed by a given load
from a generator and the power (P2) absorbed by a given load from a generator after insertion of the sample between
the generator and the load, must be primarily made up of two factors: (1) the mismatch losses and (2) dissipative
losses. The insertion loss must be expressed in dB and equal to:
10 log
10 ( P1 )
( P2 )
6.4.5 Fine structure variation: A periodic or abrupt change that appears in the plotted measurement of insertion
loss versus frequency (see figure 5).
6.4.6 Peak-to-peak variation: The variation in the characteristic impedance plot caused by mismatches or
imperfections in the coaxial assembly (see figure 6).
6.4.7 Critical resonant frequency. A critical resonant frequency is that frequency at which any point on the test
sample is observed to have a maximum amplitude more than twice that of the support points.
6.4.8 Resonant frequency: A resonant frequency is that frequency which has an amplitude that is greater than 1.5
times the amplitude of the support points.
6.4.9 Coaxial assembly classifications.
a.
Class 1: A class 1 (flexible construction) coaxial assembly is one where, during installation, bending is
required to facilitate running long lengths, where attachment to shock mounted equipment is required, and
where large angular displacements are encountered during service and maintenance conditions.
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