MIL-PRF-94 Resistors, Variable, Composition General Specification ForThis specification covers the variable resistors having a composition resistance element shaped in an arc, and a contact bearing uniformly thereon, so that a change in resistance is produced between the terminal of the contact and the terminal of either end of the resistance element when the operating shaft is turned. These resistors are capable of full load operation \(where maximum resistance is engaged\) at a maximum ambient temperature of 70 degrees C and are capable for continuous operation when properly derated, at a maximum temperature of 120 degrees C \(see 6.9\).

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MIL-PRF-94G

Motion: Resistors shall be subject to a total of 20 impacts (five blows in each of two directions in each of

two mutually perpendicular planes). One of the test planes used shall be perpendicular and the other

parallel to the longitudinal axis of the operating shaft.

Measurements during test: Each resistor shall be monitored to determine momentary discontinuity of the

element, and between the contact arm and element, by a method which shall at least be sensitive enough to

monitor or register automatically any momentary discontinuity having a duration of 0.1 millisecond (ms) or

less, as well as those of greater duration.

Examinations after shock: 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. Resistors shall

be examined for evidence of mechanical and electrical damage.

Inches

1.00

25.40

4.00

101.60

1.50

38.10

9.00

228.60

NOTES:

1. Dimensions are in inches. Metric equivalents are given for general information only

2. Tolerance is �0.02 inch (0.51 mm).

FIGURE 6. Suggested mounting fixture and resistor mounting plate

for shock and high frequency vibration tests.