Re: More Coupling...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> 

Tesla list wrote:
 
> Original poster: "BunnyKiller" <bigfoo39-at-telocity-dot-com>

> while reading all of the coupling threads, I began to wonder about the
> coupling of
> a helical primary and if anyone has done any experimenting on the
distance from
> the secondary. ( e.g. instead of having a helical primary say 2" from the
> secondary , how about having it 6 or 8" from the secondary?)
> 
> would this extra distance decrease the coupling or would it matter?

Certainly the distance affects the coupling. Actually, the coupling
coefficient for an helical primary is approximately the ratio of
the areas occupied by the secondary and primary coils, or the square
of the ratio of their diameters.
An helical coil uses less wire than any other usual form for the same 
inductance.

Antonio Carlos M. de Queiroz