MIL-PRF-26H
4.7.14 Shock, specified pulse (applicable to axial-lead resistors only) (see 3.18). Resistors shall be tested in
a.
Special mounting means: Resistors shall be mounted on appropriate jig fixtures with their bodies restrained
from movement and their leads supported at a distance of .250 inch (3.18 mm) from the resistor body.
These fixtures shall be constructed in a manner to insure that the points of the resistor-mounting supports
shall have the same motion as the shock table. Test leads used during this test shall be no longer than
AWG size 22 stranded wire, so that the influence of the test lead on the resistor shall be held to a minimum.
The test-lead length shall be no longer than necessary. In all cases, the resistor shall be mounted in relation
to the test equipment in such a manner that the stress applied is in the direction that would be considered
most detrimental.
b.
Measurement before shock: DC resistance shall be measured as specified in 4.7.2.
c.
Test condition letter I.
d.
Number and direction of applied shocks: The resistor shall be subjected to a total of 10 shocks in each of
two mutually perpendicular planes, one perpendicular and one parallel to the longitudinal axis of the resistor.
e.
Measurement during shock: Each resistor shall be monitored to determine electrical discontinuity by a
method which shall at least be sensitive enough to monitor or register, automatically, any electrical
discontinuity of 0.1 millisecond or greater duration.
Measurement after shock: DC resistance shall be measured as specified in 4.7.2.
f.
g.
Inspection after test: Resistors shall be inspected for evidence of mechanical and electrical damage.
4.7.15 Vibration, high frequency (applicable to axial-lead resistors only) (see 3.19). Resistors shall be tested in
a.
Mounting of specimens: Resistors shall be mounted on appropriate jig fixtures with their bodies restrained
from movement, and their leads supported at a distance of .25 inch (3.2 mm) from the resistor body. These
fixtures shall be constructed in a manner to insure that the points of the resistor mounting supports shall
have the same motion as the vibration test table. The fixtures shall also be of a construction that shall
preclude any resonance in the fixture when subjected to vibration within the test frequency range, and the
fixture shall be monitored for these features on the vibration table. Test leads used during this test shall be
no larger than AWG size 22 stranded wire, so that the influence of the test lead on the resistor shall be held
to a minimum. The test lead length shall be no greater than is absolutely necessary. A shielded cable that
may be necessary because of the field surrounding the vibration table, shall be clamped to the resistor
mounting jig.
Initial measurement: DC resistance shall be measured as specified in 4.7.2.
b.
c.
Test condition D.
d.
Direction of motion: In each of two mutually perpendicular directions, one perpendicular and the other
parallel to the longitudinal axis of the resistor. Six hours in each direction for a total of 12 hours.
e.
Measurement during test: Each resistor shall be monitored to determine electrical discontinuity by which
shall at least be sensitive enough to monitor or register, automatically, any electrical discontinuity of 0.1
millisecond or greater duration.
Measurement after vibration: DC resistance shall be measured as specified in 4.7.2.
f.
g.
Inspection after test: Resistors shall be inspected for evidence of mechanical damage.
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