Re: AC Resistance of wires - was 8 kHz Tesla Coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Boris,

But, I think most that desire to measure and verify these things 
would have the right equipment handy or find a way to obtain them. 
The counterpoise I use is not the best in the world, but it works. 
Your right about Q in the 300's is good (low turn coils). I've also 
measured coils at half that before (one being my high turn 8.5" coil 
if memory serves). My comment was aimed relative to the predictions 
mentioned. I expect Gerry's measurements to be far below the 
predictions. Doesn't mean the predictions are wrong as losses 
elsewhere cannot be easily separated (the age old problem). But as we 
tackle one loss at a time, eventually we will be able to break them 
all down, well, if were persistent.

Looking at Table 1 of Gary's Lossy C paper shows a very high DF for 
PVC. What I found truly amazing is that magnet wire insulation is 
also very lossy and absorbent since the losses increase dramatically 
with humidity. Very good reading!

Take care,
Bart

Tesla list wrote:

> Original poster: boris petkovic <petkovic7@xxxxxxxxx>
>
> Hi Bart,
>
> Few comments interspersed.
> -----
>
> > Original poster: "Barton B. Anderson"
> > <bartb@xxxxxxxxxxxxxxxx>
> >
> <Big Snip>
>
> > Q measurement is correct, and we all know, there are
> > a lot of "what
> > can go wrong will go wrong" when measuring Q.
> -----
> What can go terribly wrong in measuring Q of a Tesla
> coil resonator?
> With probes, low Z signal generators ,or a bit
> sophisticated device called "pinger" , obtaining Q
> under various circumstances is a relatively simple
> procedure.
> -----
>
>
> >
> > I'll be interested in what you come up with. Do you
> > have all the
> > goodies? Low Z amp? etc... If you need one, just
> > ask. I can send my
> > own your way or Terry may be able to londer his,
> > etc. I think it's
> > definitely worthwhile. Also, I would set up a flat
> > ground plane for
> > measurement somewhere where external effects are not
> > capable of much
> > influence. When I make Q measurements, I always do
> > these in the
> > backyard so that there is nothing to affect the
> > reading. I keep the
> > probe at least 10 feet away from the coil at center
> > toroid height.
> > I'll usually throw down a flat metal plate equal to
> > the toroid OD for
> > the ground plane.
> ------
> Maybe  we should also suggest using a counterpoise for
> even better preceision.
> -----
>
>
> > My personal coils have been rather
> > low Q (300's
> > range).
> -----
> Umh..come again?
> I would think Q=300 is not a low Q range for Tesla
> coils.
> -----
>
> > It will be interesting if you can measure in
> > the predicted 600's range.
> -----
> Oh yes,but I'm rather pesimistic that he will measure
> above 600.
> Solely to mention one obstacle.In the limit of a
> superconducting coil case what about dielectric loss
> at tesla coil frequencies?
> Speaking of which,G.Johnson makes some good points
> regarding that issue in his paper:
> http://www.eece.ksu.edu/~gjohnson/tcchap3.pdf
>
> All the Best,
> Boris