Re: Quick toriod question...

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

Original poster: "Brian Foley by way of Terry Fritz <twftesla-at-uswest-dot-net>" <ka1bbg1-at-mcttelecom-dot-com>

hi gary, can you check the capacitance between some of the strips? i had
even thot maybe some metalic contamination but most aluminum compounds are
nice insulators? hmm season greetings! cul brian
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, December 21, 2000 2:02 PM
Subject: RE: Quick toriod question...


> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>
> Hi Gary,
>
> I too wonder if such things could cause significant loss in a Tesla coil.
> Strips of Al tape and all are not exactly recommended RF conductors.
> Perhaps fine Q measurements between a nice copper torroid and a same sized
> heating duct job would indicate the magnitude of the loss?
>
> The tape layers overlap so the current may easily flow through the layers
> simply from the capacitance between them.  Perhaps no physical ohmic
> connection is even needed but at 200kV the current will jump if it wants
to.
>
> In the case of your real nice tape toroid, I would expect the loss between
> it and a solid one to be nil.  The beat up corrugated ones would be were
> the loss, if any, shows up.
>
> Cheers,
>
> Terry
>
>
> At 09:04 AM 12/21/2000 -0500, you wrote:
> >This thread raises another question in my mind.  It appears that most
> >home-made toroids use aluminum foil tape as the conductive surface.  But
> >even though the individual strips overlap each other, the adhesive is not
> >conductive, and an Ohm meter will indicate that they do not in most cases
> >connect to each other.  Perhaps the thinking is that when we're looking
at
> >100's of kV, a thin layer of goo is probably not going to put up much of
a
> >fight before breaking down.
> >
> >But even so, I've always wondered whether this resistance between each
tape
> >segment might have a significant effect on performance when a streamer
wants
> >to suck the energy in the toroid off in a hurry.  If each "plate" in the
> >toroid-capacitor has a resistor and a spark gap connecting it to the disk
> >terminal, that can't be good.
> >
> >I've always had access to EMI gasket material at work, used to seal
computer
> >enclosures between sheet metal surfaces to keep RF energy inside the
boxes.
> >I use this EMI gasket to connect the conductive disk to every one of the
> >aluminum tape strips.  An Ohm meter will show that each strip has a solid
> >connection to the disk.  Pictures and words of the EMI gasket as well as
my
> >new 7" x 30" custom foam toroid may be seen at:
> >http://people.ne.mediaone-dot-net/lau/tesla/foamtoroid.htm
> >(sorry about the missing spaces on the page, still working on that...)
> >
> >Back to my question - I'm wondering, am I the only person to worry about
> >connections between the tape strips?  How do others deal with this?
> >
> >Gary Lau
> >Waltham, MA USA
> >
>
>
>