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).
The construction and specifications of a coil's primary winding.
| Identifier | ExFiles\Box 164\5\ img041 | |
| Date | 9th February 1931 guessed | |
| (2) WE80 contd position by a circular spigot extension which fits over the core at the top, the H.T. terminal being in the centre of the moulding externally and the two L.T. primary terminals at each side. Bent round each side of the coil were 8 iron plates (4 each side) 3" x 3 3/4" x .013", for the purpose of additional iron in the magnetic circuit and also apparently to confine the flux path within the case. This we consider is an important feature in the design of these O.P coils. The primary winding consisted of 404 turns of 25 SWG. plain enamelled wire, weight 3 1/2 oz, wound in 6 layers as follows:- Bottom layer next to secondary 82 turns 2nd layer 75 " 3rd " 71 " 4th " 65 " 5th " 57 " 6th " 54 " Each layer was insulated with a .005" thickness of varnished paper by appearance. | ||