Re: toroid question

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

Original poster: "Metlicka Marc by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>



Tesla list wrote:
> 
> Original poster: "Malcolm Watts by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
> 
> Hi Allan,
> 
> On 27 Jan 2002, at 23:30, Tesla list wrote:
> 
> > Original poster: "Allanh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <allanh-at-starband-dot-net>
> >
> > It has occured to me that using a toroid with no conducting material in the
> > center in effect places a
> > shorted turn in the magnetic field and would cause
> > very high current to flow. Upon testing my theory on
> > my coil, I found very little difference in the two types.
> > I would like to know why the shorted turn toroid doesn't
> > consume great quantities of power.
> >
> > any ideas?

Malcolm, all

> 
> Why should having no conducting material in the centre be worse? You
> could view either form of construction as being a shorted turn,
> possibly worse in the case of a central conductor since it is closer
> to the windings.

I don't think i agree here, I see the toroid as more of a horizontal
conductive disk with the outer ridge of a large ROC. Even with a toroid
that has no conductive center, you still must run the top turn out to
connect, this makes it still a horizontal disk with a large ROC outer
ridge. I would think that a cut toroid would tend to break out at the
edges of the cut, but since i haven't tried this i couldn't say
positive?

 In fact, the requirement for anything to consume
> power is that it must be somewhat resistive. Most terminals are close
> to perfectly conducting. There can't be much doubt that the
> arrangement modifies the operating properties of the resonator to
> some degree, but then connecting something to the top of the windings
> does that anyway.

 But more due to adding top c then anything?

  Since cutting a slit in the toroid so that a
> shorted turn no longer exists has little effect on Fr (it tends to go
> up a bit if you do this), it must be telling you something about the
> way the resonator operates (how currents are distributed for example)
> and how the two interact.

It seems to me that at some point the toroid can become to big around in
relation to the coil, I find this on my little test coil, If i put the
toroid that is almost as large of outer diameter as the coil is tall.
I think that at a point the topload will start to couple with the
primaries field, this causes some real strange effects and then i think
it looks like a shorted turn?

 I'm not sure if this has been covered in
> the tssp project yet. Perhaps Paul Nicholson might care to comment?

I remember mentioning this to Paul in that with this large topload the
first streamer always broke towards the primary and contacting the upper
two thirds secondary windings, almost at right angles then they extended
to air as normal.
Take care,
Marc M.

> 
> Regards,
> Malcolm
> <snip>