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).
Table detailing the specifications for various coil primary windings.
| Identifier | ExFiles\Box 45\4\ Scan290 | |
| Date | 21th August 1925 guessed | |
| X 465 X. 918 - COIL PRIMARY WINDINGS. References: X. 079 (struck out), X. 3173 (struck out), X. 3448 (struck out), X. 4273., X. 4595. | Coil. | Number of Turns. | Number of layers. | Dia. of wire. | Gauge of wire, S.W.G. | Approx. resis. (cold) (ohms). | Approx. inductance, heneries. | |---|---|---|---|---|---|---| | GP1. | 390 | - | .020" | 25 | 1.90 | .0153 | | GP.2. | 390 | - | .020" | 25 | 1.94 | .0153 | | FP.{F. Potts}1 | 360 | - | .022" | 24 | 1.76 | .0128 | | FP.{F. Potts}2. | 360 | - | .022" | 24 | 1.84 | .0125 | | ||