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

4.8.26 Resistance to solvents (see 3.31). Resistors shall be tested in accordance with method 215 of

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

The marked portion of the resistor body shall be brushed.

The number of sample units shall be as specified in tables VI and X, as applicable.

Resistors shall be examined for evidence of mechanical damage and legibility of markings.

4.8.27 Low temperature storage (see 3.32).

4.8.27.1 Mounting. Resistors shall be mounted by their normal mounting means and in such a position with

respect to the air stream that the mounting offers substantially no obstruction to the flow of air across and around the

resistors.

4.8.27.2 Procedure. Total resistance shall be measured as specified in 4.8.5.1. Within one hour after this

measurement, the resistor shall be placed in a cold chamber at a temperature of -65OC � 2OC for a period of

24 hours � 4 hours. The resistors shall then be removed from the chamber and maintained at a temperature of

25OC � 5OC until thermal stabilization is achieved. Total resistance shall then be measured as specified in 4.8.5.1.

Resistors shall then be examined for evidence of mechanical damage.

5. PACKAGING

5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the contract or order

(see 6.2). When packaging of materiel is to be performed by DoD or in-house contractor personnel, these personnel

need to contact the responsible packaging activity to ascertain packaging requirements. Packaging requirements are

maintained by the Inventory Control Point's packaging activity within the Military Service or Defense Agency, or within

the military services system commands. Packaging data retrieval is available from the managing Military Department's

or Defense Agency's automated packaging files, CD-ROM products, or by contacting the responsible packaging

activity.

6. NOTES

(This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.)

6.1 Intended use. Resistors covered by this specification are intended for use in electronic equipment, and are

used for matching, balancing, adjusting circuit variables in computers, telemetering equipment, and other critical

applications. Resistors covered by this specification are unique due to the fact that these devices must be able to

operate satisfactorily in military systems under the following demanding conditions: 20Gs of high frequency vibration,

100 Gs of shock (specified pulse), undergo moisture resistance, setability and salt corrosion test. In addition these

military requirements are verified under a qualification system. Commercial components are not designed to

withstand these military environmental conditions.