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Re: H/D Ratios
Subject: Re: H/D Ratios
Date: Tue, 27 May 1997 20:51:09 -0700
From: Skip Greiner <sgreiner-at-wwnet-dot-com>
Organization: Greiner, Ltd.
To: Tesla List <tesla-at-pupman-dot-com>
References: 1
Tesla List wrote:
>
> Subject: Re: H/D Ratios
> Date: Tue, 27 May 1997 06:32:58 +0000
> From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
>
> At 05:55 AM 5/23/97 +0000, you wrote:
> >Subject: Re: H/D Ratios
> > Date: Thu, 22 May 1997 08:46:30 +1200
> > From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
> >Organization: Wellington Polytechnic, NZ
> > To: tesla-at-pupman-dot-com
> >
> >
> >Dear List,
> > Please indulge me once again :)
> >
> >> I have seen several references to a physical 1/4 wavelength of wire
> >> being used to wind a secondary. What is the 1/4 wave length based on?
> >> Is it free space or based on some velocity factor? Is there some magic
> >> to be had by striving for this.
> >>
> >> Based on no facts at all my next secondary will have a H/D ratio of PI.
> >> It just seems right.
> >
> >Love it :)
> > The quarter wavelength thing: In the distributed resonator, no
> >matter what the length of wire, the profile is 1/4 wavelength at
> >resonance. Well, that is _strictly_ true for no top load (or nearly
> >so because like a standard antenna, there is an end capacitance
> >effect that requires the physical length of the straight wire to be
> >somewhat shorter than the free-space length). As soon as one adds a
> >topload, the antenna/coil will resonate at a lower frequency because
> >of the additional capacitance. That makes the structure shorter than
> >90 degrees electrically at its resonant frequency. The lower the L/C
> >ratio, the more the electrical length trends towards zero degrees.
> I'd better stop there. I think I may have started writing a book.
>
> ---------------------------- Big snip
> >
> >Other comments welcome,
> >Malcolm
>
> ------------------------------------------------------------------
>
> Malcolm -
>
> I agree with you that the 1/4 wavelengths and antenna concepts for
> Tesla
> coils does not stand up to what is found with real world coils. In the
> TC
> data I have collected the secondaries of almost all of the coils do not
> conform to the 1/4 wavelength theory either for the actual or electrical
> wavelength.
>
> This makes sense because the TC is a resonant air core transformer
> with a
> copacitance load and 1/4 wavelengths are not important. The TC is a dual
> RCL
> circuit where both primary and secondary circuits must have the same
> resonant frequencies for optimum output. TCs operate the same as
> standard
> resonant transformers and helical antenna concepts are not involved.
>
> The fact that the maximum voltage is next to the top capacitance is
> typical for a transformer when the voltage is measured across the
> secondary
> coil with one end grounded. This is why any size capacitive topload can
> be
> used as long as the dual RCL circuits are in tune.
>
> Tesla always said his TC invention was not for Hertzian waves but for
> currents. Helical antennas, etc. that are Hertzian wave devices are not
> involved. I now think that the VSWR is also not involved because there
> is no
> transmission line to couple the coil and capacitor load. Note that an
> antenna is a resistive load at the end of an RF transmission line. This
> is
> not the TC type of circuit.
>
> The H/D ratio concept has only to do with maximum inductance and
> little to
> do with transformer operation. However, higher inductance does mean more
> output with resonant tranformers.
>
> John Couture
John , Malcolm and All
For the last couple of months I have worked toward achieving a secondary
in which the resonant frequency, with an appropriate top load for the
particular power input which I wished to use, equaled the 1/4 wavelength
of the wire in the secondary. The last two coils which I have built have
both achieved synergy which I define as extremely long discharges for
the power input used and automatic first notch quenching without the
addition of artificial quench gimics( air blasts and magnets, etc.) . I
personally believe that there is something to the 1/4 wavelength of the
wire length used in the secondary and have two coils which demonstrate
the fact.
Skip