scope:

This specification covers the general requirements for nonestablished reliability (non-ER) and established reliability (ER) lead screw actuated, wire wound, variable resistors with a contact bearing uniformly over the surface of the entire resistive element, wound linearly, when positioned by a multiturn lead screw actuator. These resistors are capable of full load operation (when the maximum resistance is engaged), at a maximum ambient temperature of 85°C and are suitable for continuous operation, when property derated, at a maximum temperature of 150°C (see 3.6), with a resistance tolerance of ±5 percent. The ER resistors will have life failure rate (FR) levels ranging from 1.0 percent to 0.001 percent per 1,000 hours (see 1.2.1.4). These FR levels are established at a 60 percent confidence level on the basis of life tests.

Resistors specified herein are identified by the PIN which consist of the basic number, associated specification, and a coded number. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: US Army Communications-Electronics Command, ATTN: AMSEL-LC-LEO-E-EP, Fort Monmouth, NJ 07703-5023 by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.

The style is identified by the three-letter symbol "RTR" followed by a two-digit number; the letters identify lead screw actuated, wire wound, variable resistors, and the number identifies the physical size.

The performance requirements are identified in accordance with table I.

The resistance value designator is a coded value which identifies the resistance value, maximum resolution, and maximum rated working voltage (see 3.1).

The terminals are identified by a single letter in accordance with table II.

The product level designation as shown in table III is signified by a single letter (M, P, R, S or C), which identifies the product level for which the resistor is qualified. TABLE II.Terminals.

Symbol Type of terminal ---------------------------------------------------------------- Symbol Type of terminal L Flexible, insulated-wire leads P Printed-circuit pins W 1/ Printed-circuit pins (edge mounted) X 2/ Printed-circuit pins (edge mounted, alternate configuration) Y 3/ Printed-circuit pins (staggered) 1/ Available only in essentially square styles. Pins extend from the edge 180 away from the screw head, and are parallel to the longitudinal axis of the lead screw. 2/ Available only in essentially square styles. Pins extend from the edge 90 away from the screw head, and are perpendicular to the longitudinal axis of the lead screw. 3/ Applicable to style RTR12 only.

TABLE III. Product level designator.

Product level Product level designator ----------------------------------------------- C Non-ER M 1/ 1.0 P 1/ 0.1 R 1/ 0.01 S 1/ 0.001 1/ FR in percent/1,000 hours

This appendix details the procedures for submission of samples for qualification inspection of resistors covered by this specification. The procedure for extending qualification of the required sample to other resistors covered by this specification is also outlined herein. This appendix is a mandatory part of the specification. The information contained herein is intended for compliance.

intended Use: