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Re: 3/4 wavelength secondaries



Tesla List wrote:
> 
> > Subject: Re: 3/4 wavelength secondaries
> > >Subject: Re: 3/4 wavelength secondaries
> 
> >From hullr-at-whitlock-dot-comWed Jul 24 21:43:48 1996
> Date: Wed, 24 Jul 1996 09:53:12 -0700
> From: Richard Hull <hullr-at-whitlock-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: 3/4 wavelength secondaries
> 
> Tesla List wrote:
> >
> > >From rwstephens-at-ptbo.igs-dot-netTue Jul 23 21:47:18 1996
> > Date: Tue, 23 Jul 1996 15:23:28 -0500
> > From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
> > To: tesla-at-pupman-dot-com
> > Subject: Re: 3/4 wavelength secondaries
> >
> > >>From MALCOLM-at-directorate.wnp.ac.nzSun Jul 21 22:11:11 1996
> > >Date: Mon, 22 Jul 1996 08:34:11 +1200
> > >From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
> > >To: tesla-at-pupman-dot-com
> > >Subject: Re: 3/4 wavelength secondaries

Hi Richard
> >
> > Malcolm wrote,
> >
> > >Hi all,
> > >        This from Robert caught my eye....
> >
> > >> There are no physical restrictions that I am aware of  that would
> > >> ever prevent one from winding a secondary that was the entire 90
> > >> electrical degrees (1/4 wavelength) in length and resonating it
> > >> without any sort of topload to a given Tesla coil system.
> >
> > >I'd be grateful to any body who produces data for a terminal-less
> > >coil that can do this.
> > <snip>
> >
> > >Malcolm
> >
> > Malcolm,
> >
> > If you can calculate the isotropic capacitance represented by a
> > 1/4-20 bolt about 2 inches long that might be used as a coil top
> > terminal as I gave in one of my examples, and then determine how much this
> > isotropic capacitance will 'pull' the resonant frequency of a 100 KHz
> > Tesla secondary, then I'll gladly have no objection to your refering to it as a
> > Top Load!:)
> >
> > Happy Coiling!, with or without the donut, rwstephens
> 
> Malcolm, all,
> 
> I must note that there is probably a lot of semantics here.
> 
> If one is talking about the classic formula for a quarter wave wire
> length based on frequency and the speed of light, then it will forever be
> physically impossible to wind that length of wire into a coil and
> resonate at the specified resonant frequency!
> 
> It is possible to wind a coil which, without any terminal whatsoever, can
> have a quarter wave resonant frequency of virtually any frequency
> desired!

Richard: That is the $64 question. Can you give me the dimensions or the means of 
determining the dimensions for a 1/4 wave coil...any frequency would be fine but 
hopefully between 100 and 200khz.
> 
> Finally, any terminal load, even the bolt, will lower the output
> frequency of any coil!  The 100KHZ example given by Robert would be
> affected so little as to not be worth discussing.
> 
> Richard Hull, TCBOR

Yes, agreed, anything around will lower the frequency of the coil, but we can always 
take off a few turns to get the coil close again. Malcolm and I have discussed this and 
we both do not believe it is possible. Robert W. Stephens put up an excellent post on 
this subject and indicated a coil which he wound which resonated within 3% of its 
length. I will be trying to duplicate his effort and will post my results.

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