MIL-PRF-39002 Resistors, Variable, Wirewound, Semi-Precision, General Specification ForThis specification covers the general requirements for semi-precision, wirewound, variable, resistors having a resistance element of wire, wound on an arc shaped insulated form, so that a contact bears uniformly on the resistance element, when adjusted by a contact shaft. The electrical output \(in terms of percent of applied voltage\) is linear with respect to the angular position of the contact arm. These resistors are capable of full-load operation \(when the maximum resistance is engaged\) at a maximum ambient temperature of 85 Degrees C, and are suitable for continuous operation, when properly derated, at a maximum temperature of 135 Degrees C. These resistors have a tolerance of ??5 percent.

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MIL-PRF-39002C

Examination after acceleration: Resistors shall be examined for evidence of mechanical damage.

4.6.15 Shock, specified pulse (see 3.20). Resistors shall be tested in accordance with method 213 of

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

Special mounting means: Resistors shall be mounted by their normal mounting means, with their bodies

restrained from movement on an appropriate mounting fixture. 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. 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.

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.

Measurements before shock: Total resistance and setting stability shall be measured as specified in 4.6.2.1

and 4.6.11.1, respectively.

Test-condition letter: I.

Measurement during shock: Each resistor shall be monitored to determine electrical discontinuity of the

resistance element, and between the contact arm and element, by a method that shall at least be sensitive

enough to monitor or register, automatically any electrical discontinuity of 0.1 millisecond or greater duration.

Measurements after shock: Setting stability and total resistance shall be measured as specified in 4.6.11.1

and 4.6.2.1, respectively.

Examination after shock: Resistors shall be examined for evidence of mechanical damage.

4.6.16 Vibration, high frequency (see 3.21). Resistors shall be tested in accordance with method 204 of

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

Mounting: As specified in 4.6.15a.

Test leads: As specified in 4.6.15b.

Measurements before vibration: As specified in 4.6.15c.

Test-condition letter: D.

Measurements during vibration: As specified in 4.6.15e.

Measurements after vibration: As specified in 4.6.15f, independent linearity tolerance and torque as

specified in 4.6.8 and 4.6.10, respectively.

Examination after vibration: Resistors shall be examined for evidence of mechanical damage.

4.6.17 Salt spray (corrosion) (see 3.22). Resistors shall be tested in accordance with method 101 of

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

Special mounting: As specified in 4.6.13a.

Test-condition letter: A.

Examination after exposure: Resistors shall be examined for corrosion.