Nikola Tesla Books
62 HIGH FREQUENCY APPARATUS Cor Micanite covering Primary winding End view End of winding held under tape Fig. 6.-Core and primary, showing how finishing end of primary winding is held under a loop of tape two will suffice when the coil may be removed to drain and cool. Insulation. When the primary has cooled, it may be covered with four layers of micanite sheeting. This substance is built-up mica made into a flexible sheeting about in. thick. Very thick shellac is liberally applied as the wrapping proceeds and when the final turn of the micanite is taken over the primary, the whole cylinder should be temporarily wrapped with tape until the shellac dries out thoroughly. When this is at last accomplished, the structure is to be placed in an oven until slightly warm, after which it is stood on end with the lower opening filled and the beeswax-rosin compound poured into the space between primary and insulating tube. The length of the latter is 10 in. and an inch of core is therefore left projecting at either end to permit of mounting in the frame to be described. Secondary Winding.-The secondary is wound in four sections, each section being wound in layers upon oiled paper 1½ in. wide. The wire is No. 32 S. C. C. Each layer contains 112 turns of wire and the width of the layer of wire is 1 in.; therefore, there is a margin of ½ in. on either side of the layer of wire. Each section is wound in 61 layers and the total turns to each section is accordingly 6832. The four sections will comprise 27,328 turns in consequence.
