[Prev][Next][Index][Thread]
Re: Toroid = shorted turn ?
Tesla List wrote:
>
> Original Poster: "Payne, Will E" <will.e.payne-at-lmco-dot-com>
>
> Most large top loads and especially toroids I have seen are conductive all
> the way 'round, which forms a shorted turn above the top of the coil. The
> induced EMF would create a repulsive field cancelling the ringup field, in
> effect "shading" the upper end of the secondary and wasting energy.
>
> Some coilers believe this is not a significant effect, but I remain
> skeptical. Coil behavior is pretty sensitive to the spacing between the top
> winding and the toroid, although I realize other effects are also at work
> here. I tried to insulate the joints of my stovepipe toroid and connect
> each section together at the center. The voltage at the joints would be no
> more than a hundred volts, I think. Since my joint insulation did not
> survive the assembly process, and I have plenty of more important things to
> optimize, my experiment may have to wait for the next toroid. However, I
> would like to hear from anyone else who has investigated this.
>
> Will
I have run careful measurements of several different coils here and can
detect no effect whatever on the properties of the inductor. Any
inductance change certainly less than 0.25%, and no measurable change in
the Q of a coil with an initial Q of around 300. I suppose there could
be some effect for a "short, squatty" coil (mine have length/diameter
ratios of around 4), but can't imagine any serious damange.
Ed