MIL-R-93 Resistors, Fixed, Wire-Wound, Accurate, General Specification ForThis specification covers the general requirements for accurate, wire-wound, fixed resistors having a maximum resistance tolerance of 1 percent, with the winding protected against high humidity. The resistors are rated for continuous full load operation at any ambient temperature up to 125 Degrees C, and derated up to 145 Degrees C. They are not capable for application where alternating current ac characteristics are of critical importance. Performance characteristics are in accordance with table I.

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MIL-R-93F

4.7.15 High temperature exposure (see 3.19).

a. Mounting: Resistors shall be mounted by their normal mounting means and no soldering shall be used.

b. Procedure: DC resistance shall be measured as specified in 4.7.2 at room ambient temperature.

Resistors shall then be exposed to an ambient temperature of 145°C +5°C, -0°C for a period of 24 hours ±4 hours. Not less than 2 hours after the end of the exposure period, the dc resistance shall again be measured as specified in 4.7.2, at room ambient temperature.

4.7.16 Shock, specific pulse (see 3.20). Resistor shall be tested in accordance with method 213 of

MIL-STD-202 . The following details and exceptions shall apply:

a. Special mounting means: Resistors 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.

(1) Wire lead terminal resistors: Resistors shall be rigidly mounted on appropriate jig fixtures with their bodies restrained from movement and their leads supported at a distance of 0.25 inch from the resistor body. These fixtures shall be constructed in a manner to insure that the points of the resistor mounting supports will remain in a static condition with reference to the shock table.

b. Test leads: 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 will be held to a minimum. The test lead length shall be no longer than necessary.

c. Measurement before shock: DC resistance shall be measured as specified in 4.7.2. d. Test condition: I.

e. Number and direction of applied shocks motion: The resistors shall be subjected to 5 shocks (total of 15 shocks) in each of 3 mutually perpendicular planes. The initial plane shall pass through the resistor axis and terminals and the other two planes shall be mutually perpendicular.

f. 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.

g. Measurement after shock: DC resistance shall be measured as specified in 4.7.2.

h. Examination after test: Resistors shall be examined for evidence of mechanical and electrical damage.