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 table for various types of coil primary windings.
| Identifier | ExFiles\Box 45\4\ Scan190 | |
| Date | 17th August 1923 | |
| X4079 Typed 17.8.23. X.918- COIL PRIMARY WINDINGS. X.4079. X.4273. X.3173. X.4596. X.3445. | Coil. | Number of turns. | Number of layers. | Dia. of Wire. | Gauge of wire. S.W.G. | Approx. resis. (cold) (Ohms). | Approx. inductance (Henries). | |---|---|---|---|---|---|---| | Short { A | 450 | 6 | .024" | 23 D.S.C. | 1.86 | .024 | | { B | 300+20 | 6 | .040" | 19 D.S.C. | .54 | .010 | | { C | 220 | - | - | - | .32 | .0056 | | Z | 366+20 | 6 | .032" | 21 D.S.C. | .86 | .014. | | G | 300+10 | 6 | .036" | 20 E.C.C. | .63 | .010 | | Tall { T&G | 300 | 4 | .032" | 21 D.S.C. | .68 | .010 | | { T&S | 300 | 4 | .028" | 22 E.C.C. | .66 | .010 | 15.8.23. EFC. | ||