This might give you a bit more info:
http://www.rfpowersystems.com/products.htmNote that on this type of transformer, the tubes thru the core are the single turn, while the wires are the secondary. Thus a transformer with 3 turns is a 1:9 ratio. 4 turns is 1:16 ratio. The ratio is always 1:(N*N) or the number of turns squared.
RF Power Systems has some pretty good drawings of the transformers - they are not that hard to make if you've got the ferrites.
73 de Ken H>
