Re: Sonotube's high RF loss!...yes or no?

["Mark L. Fergerson" <mfergerson1-at-xxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

  The microwave-oven test is just a "rule of thumb" thing; as others
have pointed out, very few TC's operate at 2.54 (IIRC) GHz. Looking for
RF absorption that high may seem silly, and as you say even ceramics and
glass will heat up (melt?? wow!) at that freq., but you gotta start
somewhere. I s'pose the "right" thing to do would be to assemble a bunch
of candidate materials the same size and use them as inserts in the same
coil and run as close to identical tests as possible while monitoring RF
power transfer. Since to my knowledge nobody's done that, well, just use
what works for you, I guess.

 Since we're (still) on the subject of other materials for TC forms,
what "exotic" materials have been used and rejected i.e. various
plastics, glasses, and so on? From first principles, I'd have said glass
was the ideal material, but nobody seems to recommend it. There needs to
be a TC-specific FAQ on this somewhere IMHO. Looking up RF absorption
curves for various materials can be a pain because researchers will look
for losses in their area of interest (what they're funded to do) which
sometimes leaves us out in the cold. The Devil's in the details.

  Mark L. Fergerson

Tesla list wrote:
> 
> Original poster: "Albert Hassick" <uncadoc-at-juno-dot-com>
> 
> Hi all , I wonder if sonotube or quikrete tube chunks in the microwave
> mean anything at all.  Since I can get pvc and cpvc and abs tubes to get
> very hot, yes, too hot to hold when I nuke them in my microwave oven.  So
> what does that mean?  If you ask me, I will say that any and all
> substances can be heated in a microwave oven.   I will point out to you
> that we use our microwave oven to set ceramics and fuse and melt
> decorative particles of glass.  So the sandy/clay/glass mix gets hot and
> fuses.  Kind of a super kiln!  I can melt plastic tube in my microwave,
> AND it deforms and bubbles terribly! ANd it is a hot sticky mass that
> cannot be touched by hand.   The neat thing is that when the plastic tube
> is melting away and collapsing that the cardboard tube next  to the
> bubbling plastic tube still retains its shape and integrity while the
> plastic tube deforms and collapses!  So what are we to gather here? Is
> the ultimate Telas coil secondary/tertiary wound in plastic or cardboard?
>   AL.
> 
> n Sun, 29 Oct 2000 18:35:56 -0700 "Tesla list" <tesla-at-pupman-dot-com> writes:
> > Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> >
> > Hi,
> >
> > I stuck a chunk of Sonotube in the microwave for 15 seconds.  In
> > that short
> > time, it got too hot to hold!!!  Something is lossy there!
> >
> > Cheers,
> >
> >       Terry