From: "Malcolm Watts"
Date: Mon, 11 Sep 2000 09:11:02 +1200
Subject: Re: [TSSP] Mystery of the missing loss
Hi Terry, all,
My antennae shot up when I read this:
> >3.)Possibly extra high dielectric loss in coil form
> > (unlikely here I think)
>
> Now this I can NOT rule out! The secondary seemed to have much higher loss
> at low frequencies than at high!! Using my vacuum cap (which actually
> showed a loss higher than my super cap!) I could clearly see that higher
> frequencies had higher loss. Here is a little chart I made of the
> effective secondary resistance vs. frequency. I made it with the vacuum
> cap by varying the capacitance and finding the effective Rac.
>
> http://216.160.168.190/TeslaCoils/Misc/PaulNich/BRacvF.gif
>
> Basically, it says something is getting very lossy very fast as frequency
> increases. I have no idea what, but the larger toroid case was probably
> less lossy due to the frequency being lower rather than the fields and such.
***********>
***********>
> This secondary is a 1/8 inch thick cardboard impregnated with paraffin wax
> "sonotube" used for circular concrete forms. This wire may have had an
> oxide layer at the surface before it was coated. The vacuum cap is
> probably more lossy at low capacitance than high Maybe the polyurethane
> coating is doing something... The list goes on... but I seem to be
> getting super high loss as frequency increases.
My one *really* bad secondary (which I actually threw away)
was wound on sonotube with the tar layer removed. That coil
was spacewound to boot!
I don't think the polyurethane is the culprit. More
likely the paper form. Wax is possibly also not the best.
Remember those old transformers from the forties? which went
o/c in the sixties? the rotted copper inside complete with
verdigris (sp?)? I never decided whether they were trapping
moisture inside or admitting it.
> >4.)EM Coupling of secondary with enviroment and losses
> >outside a coil structure.
>
> I have done such tests a number of times in a number of places and gotten
> similar results. I don't have an oxygen free silver plated room coated
> with a gold anti-oxidation layer or anything, but the room is not all that
> unusual... I would guess the previous option three...
I think that is a good bet. The room does make difference once
Q's get beyond a hundred or so but not to that extent (say six
foot clearance all round).
> >
> >I don't belive that Terry made serious mistakes
> >relating 2 and 3.Neither that the reason for very high
> >Garry Johnson's secondary coil Q in order of 500
> >is some kind of superior secondary construction.
> >But I do belive it is due to point 4.
> >That would be the reason:Enviroment and resonator
> >position in it.
> >I'm quite convinced Terry's secondary coil Q results
> >would be much better in different enviroment
> >conditions.
>
> I have played with some modelling and I think the "room" is far enough away
> that it should not be a factor. It is raining now so outside is not an
> option. There are a number of things in the Rac loop but the coil form
> really does seem lossy to me...
Me too.
Regards,
malcolm
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.