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Braided or Smooth Strap
> , throw the braid away and use pipe, copper strap, v. thick
> wire, *anything but*.
Quoting rwstephens:
> Thank you both for your input on this subject. Malcolm, that
> test data you re-posted for my benefit and that of others was
> most interesting. Implications would appear that even the wire
> used to wind the secondary should bear more consideration. In
> my two cases to date of larger coils I have used #12 AWG THHN
> tinned copper stranded, plastic insulated wire, PVC with a
> clear nylon outer sheath I think, and #18 AWG, PVC coated
> stranded tinned copper. Malcolm, your test results indicate
> that silver covered, solid copper wire with Teflon or Poly-
> ethylene outer sheath would be the best secondary wire
> for a large coil system. Here I was proposing to possibly wind
> a large secondary with RG-59, employing the outer shield as
> the conductor. Guess I'll have to re-think that one!
<snipage>
> Have either of you considered 'why' bare coax outer braid is
> poor? Is it because the individual wires which are woven
> together do not 'talk' to each other contact wise at RF and
> what we end up with is, by the nature of the weave, a whole
> bunch of parallel conductors, ala litz wire, but measurably
> longer than the actual length of the finished cable. Such that
> a 10 foot section of coax in this series resistance concept,
> actually represents a 15 foot or so length which makes it
> measure poorer than a real 10 foot length of solid single
> wire?
There are a bunch of reasons. Off axis inductance, longer
electrical pathways, higher RF impedance (the shorter paths are
frequently insulated with manufacturing oil), and the outer
insulating sheath on commercial coax is the cheaper (and higher
loss) PVC. Take your pick or add them up.
Richard Quick
... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12