MIL-PRF-39035 Resistor, Variable, Nonwirewound \(Adjustment Type\), Nonestablished Reliability, And Established Reliability, General Specification ForThis specification covers the general requirements for nonestablished reliability \(non-ER\) and established reliability \(ER\), multiturn lead-screw actuated, and single-turn, nonwirewound, variable resistors with a contact bearing uniformly over the surface of the entire resistive element, when positioned by an actuator. These resistors are capable of full-load operation \(when the maximum resistance is engaged\), at a maximum temperature of 150 Degrees C, with a resistance tolerance of ??10 percent. The ER resistors will have life failure rate levels ranging from 1.0 to 0.001 percent per 1,000 hours \(see 1.2.1.5\). These failure rate levels are established at a 60 percent confidence level maintained at 10 percent producer\'s risk on the basis of the life tests.

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MIL-PRF-39035E

3.9 Contact resistance variation. When measured as specified in 4.8.3, the contact resistance variation shall not

exceed �3 percent or 20 ohms for characteristic C, and �3 percent or 3 ohms for characteristics F and H, which ever

is greater.

3.10 Integrity of shaft (not applicable to style RJR32). When resistors are tested as specified in 4.8.4, there shall

be no evidence of shaft breakage, and the shaft shall remain in one piece.

3.11 DC resistance.

3.11.1 Total resistance. When measured as specified in 4.8.5.1, the total direct current (dc) resistance shall not

deviate from the specified nominal resistance (see 3.1), by more than �10 percent.

3.11.2 End resistance. When measured as specified in 4.8.5.2, the end resistance for all characteristics shall not

exceed 2 ohms or �2 percent of the total resistance, which ever is greater.

3.11.3 Resistance value deviations. All maximum deviations as specified in this section are to be considered

absolute limits with the exception of the contact resistance adjustments.

3.12 Immersion (not applicable to L terminals). When resistors are tested as specified in 4.8.6, no continuous

stream of bubbles shall emanate from any concentrated point of the resistor. When resistors are subjected to the dye

penetrant test, there shall be no evidence of dye in the internal cavities.

3.13 Actual effective electrical travel. When resistors are tested as specified in 4.8.7, the number of turns of the

operating shaft necessary for the contact arm to traverse the resistance element shall be as specified (see 3.1).

3.14 Dielectric withstanding voltage. When resistors are tested as specified in 4.8.8, there shall be no evidence of

damage, arcing, or breakdown. The leakage current shall not exceed one milliampere.

3.15 Insulation resistance. When resistors are tested as specified in 4.8.9, the dry insulation resistance shall not

be less than 1,000 megohms.

3.16 Torque.

3.16.1 Operating. When resistors are tested as specified in 4.8.10.1, the minimum torque required to move the

contact arm shall be 0.05 ounce-inch and the maximum torque required shall be as specified (see 3.1).

3.16.2 Clutch (applicable only to multiturn adjustment type units, unless otherwise specified). When resistors are

tested as specified in 4.8.10.2, the contact arm shall idle against the stop without electrical discontinuity or evidence

of mechanical damage. The travel of the contact arm shall also be capable of reversing direction.

3.16.3 Stops (applicable only to single turn units, unless otherwise specified). When resistors are tested as

specified in 4.8.10.3, they shall withstand the stop torque specified (see 3.1), without damage to the contact arm or

stop.

3.17 Thermal shock. When resistors are tested as specified in 4.8.11, the change in total resistance shall not

exceed �2 percent for characteristic C, and �1 percent for characteristics F and H. The change in setting stability

shall not exceed �1 percent. There shall be no electrical discontinuity or evidence of mechanical damage.

3.18 Solderability (not applicable to terminal L). When resistors are tested as specified in 4.8.13, they shall meet

the criteria for wire-lead terminal evaluation in the test method.