PRODUCTION FACILITIES FOR MULTI-TURN METALFILM TRIMMER RESISTORS PER SIGNAL CORPS TECHNICAL REQUIREMENTS SCS-127 DATED 9 FEBRUARY, 1962, AND MIL-R-22097B (MODIFIED).
Abstract:
Favorable load life data on 50K units was obtained when the load life temperature was reduced from 125C old SCL-6111 requirement to 85C new MIL-R-22097B requirement. Favorable data has been obtained for the following additional characteristics Load life to 2000 hours 50K units, High temperature exposure, Thermal cycling, and T.C. to 60 ppm 5K units. The fit of the contact holder in 10 and 25 turn units has been improved correcting a mechanical assembly problem. Although substitution of Rolube for the teflon insulators had corrected the problem of shift during final encapsulation, the source was found to be unreliable. A replacement for the Rolube has been found by molding the parts of Fiberite epoxy resin. This is being done in house in a test mold with satisfactory results. A production mold will be ordered. A change in pin material still within the contract requirements has been made from silver plated copper to gold plated nickel. This was done to make one unit compatible with users employing both printed circuit soldering and welded modules.