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Re: Tapered Secondary Coil
Tesla List wrote:
>
> > > > Subject: Tapered Secondary Coil
> > > Subject: Re: Tapered Secondary Coil
> > > > Subject: Tapered Secondary Coil
> > Subject: Re: Tapered Secondary Coil
> > > > Subject: Tapered Secondary Coil
> > > Subject: Re: Tapered Secondary Coil
> > > > Subject: Tapered Secondary Coil
>
> >From bert.hickman-at-aquila-dot-com Fri Dec 6 23:43:26 1996
> Date: Fri, 06 Dec 1996 06:41:49 -0800
> From: Bert Hickman <bert.hickman-at-aquila-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Tapered Secondary Coil
>
> Tesla List wrote:
> >
> > > > Subject: Tapered Secondary Coil
> > > Subject: Re: Tapered Secondary Coil
> > > > Subject: Tapered Secondary Coil
> >
> > >From sgreiner-at-mail.wwnet-dot-com Thu Dec 5 22:59:16 1996
> > Date: Thu, 05 Dec 1996 15:17:29 -0800
> > From: Skip Greiner <sgreiner-at-mail.wwnet-dot-com>
> > To: tesla-at-pupman-dot-com
> > Subject: Re: Tapered Secondary Coil
> >
> > Tesla List wrote:
> > >
> > > > Subject: Tapered Secondary Coil
> > >
> > > >From bert.hickman-at-aquila-dot-comSat Nov 23 20:04:43 1996
> > > Date: Sat, 23 Nov 1996 09:35:07 -0800
> > > From: Bert Hickman <bert.hickman-at-aquila-dot-com>
> > > To: tesla-at-pupman-dot-com
> > > Subject: Re: Tapered Secondary Coil
> > >
> > > Tesla List wrote:
> > > >
> > > > >From scottb-at-aca.caFri Nov 22 20:30:34 1996
> > > > Date: Fri, 22 Nov 1996 15:37:04 -0500
> > > > From: scottb-at-aca.ca
> > > > To: tesla-at-pupman-dot-com
> > > > Subject: Tapered Secondary Coil
> > > >
> > > > I have seen some secondaries that are tapered, and some that are not. What
> > > > (mathematically) is the difference, and what are the effects??
> > > >
> > > > /sb
> > >
> > > Scott,
> > >
> > > A tapered secondary (with the larger diameter at the bottom) has
> > > decreasing inductance per turn as you go higher up the coil. When used
> > > as a resonator with little or no top-loading (small discharge terminal),
> > > it exhibits a less well-defined resonant frequency (i.e., lower Q) than
> > > a constant diameter resonator. The characteristic impedance of a tapered
> > > resonator also varies with height, being higher Z at the botttom, and
> > > lower at the top. A tapered resonator also has substantially less
> > > "lumped" inductance than one with constant diameter (equal to the base).
> > >
> > > A tapered resonator will see less overall resonant rise than a
> > > constant-diameter resonator of the same height and base-diameter.
> > > However, it should also be less sensitive to detuning from stray
> > > capacitance. Because most of the inductance is concentrated in the lower
> > > half, the voltage stress at the bottom portion is greater than for a
> > > constant diameter coil. Addition of significant top-loading capacitance
> > > should sharpen the tune somewhat, but the resonator will retain its
> > > distributed parameter (transmission-line) characteristics to a greater
> > > degree than a constant diameter resonator.
> > >
> > > There appears to be no marked performance advantage in using a tapered
> > > resonator versus a standard helix in a 2-coil system. However, it sure
> > > looks different...
> > >
> > > Safe coilin' to you!
> > >
> > > -- Bert --
> >
> > Bert and all
> >
> > Has anyone tried to build a tapered resonator and run it upside down,
> > ie., drive the thing at the small end. Couple of interesting
> > observations: the top of the coil is self shielding, no toroid is
> > necessary, the distributed parameters (inductance) may enhance the
> > voltage rise.
> >
> > I will build one if someone can give me a reasonable way to do it.
> >
> > Skip
>
> Skip,
>
> I haven't built one, but you've got my curiosity aroused. I'd suspect
> you'd still want to use a toroid to prevent premature breakout from the
> top of the coil. The inductive coupling from the primary to the smaller
> base of the coil may also be significantly poorer, but might be
> compensated for by using a matching inverse conical primary. It'd be
> interesting to see if there were any unsuspected advantages!
>
> I'd make a conical coilform template out of posterboard, and once I was
> satisfied with the rolled up results, make the same out of thin (30 mil)
> LDPE sheet material, and once rolled into a cone, secure it with small
> strips of insulating tape. Obviously, you're going to have to figure out
> some way to rigidly mount the small base end to hold it in the top-heavy
> position...
>
> Good Luck, and safe, inverted, coilin' to ya, Skip!!
>
> -- Bert --
Bert
There are several ways to make a cone and yours is a simple one. My
problem is how to hold the wire to the cone. I have tried to wind
several coils but the turns always collapse unto each other. The problem
is exacerbated when the coil is inverted. The wire has a tendency to
just fall off.
Anyone...any ideas?
Skip