RE: Quick toriod question...

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

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
>