From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Specification sheet for insulated resistors detailing their dimensions and electrical ratings.
| Identifier | ExFiles\Box 63\2\ scan0313 | |
| Date | 18th June 1937 guessed | |
| INSULATED RESISTORS DIMENSIONS type No. Nominal rating Nominal dia. Nominal length Maximum dia. Maximum length Dia. of leads Length of leads 3N 1/2 or 3/4 watt 0.220" 11/16" 0.240" 11/16" .032 1 1/2 ± 1/8" 4N 1/4 or 1/3 0.220 7/16" 0.240" 7/16" .032 1 1/2 ± 1/8" RATING. Recommended voltage Continuous rating Overload rating Maximum voltage rating 3N 1/2 or 3/4 watt 200 1 watt 1 1/4 watt 300 4N 1/4 or 1/3 150 1/2 watt 0.7 watt 200 Note: All ratings are for eight either DC or AC (RMS) except the maximum voltage rating, which is for peak values of applied voltage. Ratings are on ambient conditions 40°C. External insulation test 3000 v.{VIENNA} RMS | ||