MIL-R-26 Revision F, November 16, 1993
RESISTORS, FIXED, WIRE-WOUND (POWER TYPE)
Includes all amendments and changes through Amendment 4, December 9, 1997
This specification covers the general requirements for power type, wire-wound, fixed resistors for use in electrical, communications, and associated equipment. Included are general purpose styles of 5 percent initial resistance tolerance with power ratings ranging from 3 to 240 watts at 25°C, derated to 0 power at 350°C (characteristics N and V) and precision axial lead types of .1, .5, and 1 percent initial resistance tolerances with power ratings ranging from 1 to 10 watts at 25°C, derated to 0 power at 275°C (characteristic U). Table I of supplement 1 provides a summary of performance characteristics for these resistors.
The PIN shall be in the following form (see 3.1):
The style is identified by the two-letter symbol "RW" followed by a two-digit number; the letters identify power type, wire-wound, fixed resistors, and the number identifies the size, wattage rating, and construction of the resistors (see 3.1).
The characteristic is identified by a single letter that identifies the maximum continuous operating temperature (surface hot spot), the high ambient temperature derating (see 3.1), the minimum insulation resistance value, and the degree of moisture resistance in accordance with the applicable detail specification (see 3.1).
The nominal resistance expressed in ohms is identified by a three or four digit number in accordance with the applicable detail specification (see 3.1). Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to U.S. Army Research Laboratory, ATTN: AMSRL-EP-RD, Fort Monmouth, NJ 07703-5601 by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.
The resistance tolerance, when applicable, shall be identified by a single letter in accordance with the applicable detail specification (see 3.1).
The nominal power ratings for the various styles and characteristics shall be as specified (see 3.1).