Re: Extra coil

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Mark, 
         The Corums built a cavity resonator TC. They introduced a 
simple coupling link into the cavity. Obviously, it operated at 
frequencies way beyond our rather LF machines.

Regards,
Malcolm

On 9 Feb 2002, at 20:58, Tesla list wrote:

> Original poster: "Mark Fergerson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <mfergerson1-at-home-dot-com>
> 
> Tesla list wrote:
> > 
> > Original poster: "Nebojsa Kovacevic by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <morfeus-at-EUnet.yu>
> > 
> > Hello Mark!
> > 
> > Very good explanation. Tesla discovered that a long coil of wire behaves as
> > a sort of "electromagnetic
> > organ pipe". Some people think that this is important for creating an
> > "invisible wall" using TC. The
> > prediction is:  if we "modulate the field harmonics" a bit so that the
> > voltage maximum does NOT appear
> > at the end of the coil, but instead appears a few inches away...
> 
>   Then we (you, Antonio [if you're reading this], and I) agree
> that you were suggesting the "extra coil" is modellable as a
> generic resonator, and might be replaced with a microwave cavity
> to be (inefficiently, I suspect) shock-excited by an "ordinary"
> TC?
> 
>   As I mentioned, I'm interested in the limits of TCs, including
> the possibility of a microwave version.
> 
>   Now I'm wondering about the coupling method. With a typical
> hollow, metallic cavity, capacitive seems out because of the
> likelyhood of arc-over, unless the cavity be very large. Magnetic
> seems unlikely for the same reason, unless the input and output
> "loop" be large. What's left? A dielectric resonator? AIUI they
> can be coupled in and out by "evanescent waves" merely using
> nearby conductors. I'm referring to a vague memory of  an article
> I read that described DROs (Dielectric Resonant Oscillators)
> built for several GHz using little discs of synthetic sapphire (I
> think) and stripline coupling circuitry. But I don't know much
> about how to determine impedance and Q for DRs.
> 
>   Even without output coupling circuitry, it sure wouldn't look
> like an ordinary Maggie, with streamers coming off the end of a
> chunk of an obvious insulator!
> 
>   As to your latter speculation, how do you force a voltage
> antinode _off_ the physical coil? ISTM that at resonance you
> _must_ have an antinode on at least one end of a nxlambda/2
> (where n is odd) long resonator, and a node on the other end.
> Even if you're running off-resonance, a node can appear off the
> end of the coil, not an antinode.
> 
>   OTOH Antonio, if you're reading this, and the above is actually
> possible, am I right in intuiting it could be part of the cause
> of racing sparks? Since no TC system really operates at one
> frequency, but at two or more, whose separation is determined
> (largely) by the coupling, perhaps the one which is "shorter"
> than the length of the coil can somehow "yank" the antinode off
> the bottom of a, say, improperly RF-grounded secondary? Or will
> any interference be more likely manifested at the topload?
> 
>   Mark L. Fergerson
> 
> 
> 
>