Topband: Teflon tubing in binocular ferrites

[kurt-erich.finger at arcor.de]

I read the intereting discussion about using binocular type ferrites for transformers in this reflector (Feb 2006). I understand that the wire should be in an additinal tube to avoid scratching the enamel from the wire. But why is teflon recommended  in receiving  transformers? Shouldn't PVC isolated wires do the job? If I put the wires in tube I increase the distance beween primary and secundary and thus reduce the capacity. Is this right? I have some small diameter tubes used in the chemical laborarory with a larger wall thcikness. I assume that they would decrease the capacity even more, or?

cheers

Kurt-Erich

PS
I read the discussion "What is a turn" in this reflector. A short remark. Binocular cores are on the market for at least  17 years. I have a brochure from Amidon where they defined what a turn is.  A round-trip.

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