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).
Coil XQP15, which has been modified with 2,000 extra turns on its secondary winding.
| Identifier | ExFiles\Box 69\1\ scan0193 | |
| Date | 12th April 1929 | |
| EFC. X6710 12.4.29 Herewith coil XQP15 This is the coil from you recently asked for with 2,000 turns extra on secondary winding. E.J.Brock. | ||