MIL-PRF-94G
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4.7.13.2 Cycling. Sample units shall be conditioned at 70 C ±5 C for 24 hours ±4 hours. The sample unit shall be
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returned to room ambient (25 C ±5 C) an allowed to stabilize. After stabilization, the initial resistance reading shall
be taken. The sample units shall then be subjected to applicable thermal shock shown in table XV for a total of five
cycles performed continuously. In transferring the sample units from one chamber to another, they shall not be
subjected to circulating air. The air temperature of the two chambers shall be held at each of the extreme
temperatures by means of circulation and sufficient hot or cold chamber capacity so that air at the sample units will
reach the temperature specified within 2 minutes after they have been transferred to the appropriate chamber. The
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final resistance reading shall be taken at the end of thermal shock at 25 C ±5 C after the samples have been
stabilized.
TABLE XV. Thermal shock.
Time in minutes
Temperature
Steps
o
( C)
(minimum)
30
1
-55 +0, -3
10 to 15
2
25 +10, -5
30
3
120 +3, -0
4
10 to 15
25 +10, -5
NOTE: At the option of the manufacturer the reverse sequence may be as follows:
1. Room Temperature
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2. +120 C ±3 C
3. Room temperature
4. -55OC ±3OC
4.7.14 Salt spray (corrosion). Resistors shall be tested in accordance with method 101 of MIL-STD-202. The
following details shall apply (see 3.17):
a.
Special mounting: On an aluminum panel.
b.
Test condition: A.
c.
Examination after exposure: Resistors shall be thoroughly washed for 1 minute in free-running tap water,
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the temperature of which shall not exceed 38 C. The resistors shall then be placed in an oven maintained
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at 50 C ±3 C, for a period of 24 hours ±4 hours. At the end of this period, resistors shall be removed from
the oven, disassembled, and examined for corrosion of internal surfaces.
4.7.15 Shock (specified pulse). Resistors shall be tested in accordance with method 213 of MIL-STD-202. The
following details and exception shall apply (see 3.18):
a.
Special mounting means: Resistors shall be mounted by their normal mounting means on an appropriate
mounting fixture. A suggested mounting fixture is shown in figure 6. The mounting fixture shall be
constructed in such a manner as to insure that the mounting supports remain in a static condition with
reference to the shock test table. Test leads used during this test shall be as small as a wire size as
practicable (e.g., AWG 22 stranded) so the influence of the test lead on the resistor will 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 which
would be considered most detrimental. The contact arm shall be positioned at 50 percent of mechanical
rotation. The locking bushing styles be in the locking position.
b.
Measurements after mounting: Resistors shall be measured as specified in 4.7.2. The resistance shall be
measured between the contact arm terminal and terminal 1 and between terminals 1 and 3.
c.
Test condition: I.
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