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

3.29 Marking. Resistors shall be marked in accordance with MIL-STD-1285, with the PIN and the manufacturer's

name or code symbol and date code. The date code shall be in accordance with MIL-STD-1285. The circuit diagram

shall be marked on the resistor as specified in 3.4.5.1. The location of the manufacturer's code symbol shall be at the

discretion of the manufacturer. There shall be no space between the symbols which comprise the PIN. If lack of

space requires it, the PIN may be placed on two lines or on separate surfaces. In this event, the PIN shall be divided

between the temperature characteristic and terminal symbols, as shown in the following example:

RK09SAC

S101

Marking shall remain legible at the end of all tests.

3.30 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally

preferable materials should be used to the maximum extent possible, provided that the material meets or exceeds the

operational and maintenance requirements, and promotes economically advantageous life cycle costs.

3.31 Workmanship. Resistors shall be processed in such a manner as to be uniform in quality and shall be free

from holes, fissures, chips, corrosion, and malformation; the terminals shall be unbroken and not crushed or nicked;

and the resistors shall be free from other defects that will affect life, serviceability, or appearance.

4. VERIFICATION

4.1 Classification of inspection. The inspection requirements specified herein are classified as follows:

Qualification inspection (see 4.4).

Conformance inspection (see 4.5).

4.2 Test equipment and inspection facilities. Test equipment and inspection facilities shall be of sufficient

accuracy, quality, and quantity to permit performance of the required inspection. The supplier shall establish

calibration of inspection equipment to the satisfaction of the Government.

4.3 Inspection conditions. Unless otherwise specified herein, all inspection shall be made in accordance with the

test conditions specified in the "GENERAL REQUIREMENTS" of MIL-STD-202.

4.3.1 Precautions. Adequate precautions shall be taken during tests to prevent condensation of moisture on

resistors, except during the moisture-resistance and thermal-shock tests.

4.4 Qualification inspection. Qualification inspection will be performed at a laboratory approved by the

Government (see 6.3).

4.4.1 Sample. The number of sample units comprising a sample of resistors to be submitted for qualification

inspection shall be as specified in the appendix to this specification.

4.4.2 Test routine.

4.4.2.1 Sample units with S-type terminals. Sample units with S-type terminals will be subjected to the

qualification inspection specified in table II, in the order shown. Thirty enclosed sample units will be subjected to the

inspection of group I; they will then be divided equally into five groups of six units each, for group II to group VI,

inclusive, and subjected to the inspection for their particular group. The two unenclosed sample units will be

subjected only to the visual and mechanical examination of group I. The 12 sample units of the locking-bushing type

will be subjected to test group I. They will then be divided equally into two groups of six units each, for group II and

group VI, and subjected to the inspection for their particular group.

4.4.3 Defectives. Defectives in excess of those allowed in table II shall be cause for refusal to grant qualification.