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).
Establishing the new standard production test for a 22 SWG primary coil with double ballast resistance.
| Identifier | ExFiles\Box 70\4\ scan0023 | |
| Date | 9th June 1928 | |
| X8781cl To BY.{R.W. Bailey - Chief Engineer} from EFC. c. Mr. Brock. c. Mx.{John H Maddocks - Chief Proving Officer} EFCl/T9.6.28. PRODUCTION TEST OF 22 SWG. PRIMARY COIL WITH DOUBLE BALLAST RESISTANCE. Please find attached copy of our amended production test for the coarser primary coil rearranged suitably for test with the double value ballast resistance, and with a .55 make ratio for contact breaker in place of .5. This now becomes the standard production test for coils. EFC. | ||