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 of specifications for coil primary windings.
| Identifier | ExFiles\Box 49\5\ Scan055 | |
| Date | 25th September 1929 | |
| X4273 25.9.29. X.918 - COIL PRIMARY WINDINGS. X.4079, X.4273, X.3173, X.3445, X.4596. X.8710, X.4501. Short. { Coil. | Number of turns. | Number of layers. | Dia.of wire. | Gauge of wire. | Approx. resis. (cold).(ohms). | Approx. inductance (henries). A | 450 | 6 | .024" | 23 D.S.C. | 1.86 | .024 B | 300 | 6 | .040" | 19 D.S.C. | .54 | .010 Z | 366 | 6 | .032" | 21 D.S.C. | .86 | .014 G | 300 | 6 | .036" | 20 E.C.C. | .63 | .010 } TG | 300 | 4 | .032" | 21 D.S.C. | .68 | .010 TS | 300 | 4 | .028" | 22 E.C.C. | .92 | .010 TR {Capt. F. W. Turner - Finance} | 300 | 4 | .028" | 22 E.C.C. | .92 | .010 GP | 390 | 4 | .020" | 25 E.C.C. | 2.20 | .015 LS | 300 | 4 | .028" | 22 E.C.C. | .92 | .010 LC | 242 | 4 | .032" | 21 E.C.C. | .65 | .007 | ||