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Re: Off-axis primary inductance



Tesla List wrote:
> 
> Original Poster: Gary Lau  22-Nov-1998 1518 <lau-at-hdecad.ENET.dec-dot-com>
> 
> >"I had heard the well circulated wive's tale that off axis L would waste
> >energy.  This test graphically proved that it does not.
> >
> >The practical conclusion is that it IS technically acceptable to place a
> >high quality air core tuning coil in series with the Tesla coil primary
> >coil in order to achieve 'fine tuning' without throwing away hard won RF
> >tank circuit energy!
> >
> >Real valuable knowledge gleaned by the actual doing.
> >
> >Robert W. Stephens
> 
> This sounds reasonable.  Now it makes me wonder about the importance of
> low ESL tank capacitors.  If it's okay to have inductance scattered
> anywhere throughout the tank circuit as long as one's coupling is not
> compromised and pri/sec resonance is maintained, why should ESL matter?
> Could it be that only dielectric, and DC plus skin-effect resistive losses
> matter in the tank?  Or is capacitor ESL correlated to resistive losses
> in the cap as well?
> 
> Gary Lau
> Waltham, MA USA

Gary,

You raise an interesting question.  Certainly ESL is an important and
limiting factor in pulse circuits where fast rise time is crutial, but
Tesla coils operate in the basement of the EM radio spectrum where the
RF sinewave is drawn in a comparatively non-hectic manner. Unfortunately
a cap made to the exacting standards that equal a low ESL will also
display a low ESR.  It may be difficult to obtain evidence available by
lab testing of commercial offerings to completely answer your question.
Anyone out there wanna roll some home made poly caps out'a nichrome
foil?

Robert W. Stephens