On 29 Nov, 09:42, "Tom Donaly" wrote:
Gene Fuller wrote:
Cecil Moore wrote:
Tom Donaly wrote:
What is the characteristic impedance of Tom's coil?

A few thousand ohms. Use equation 50 at:

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf

What's your formula for the velocity factor of Tom's coil? Is it from
the same Tesla coil crackpot you quoted in previous posts?

Do you reject all IEEE white papers? The formula
is equation 32.

Cecil,

Have you actually read and understood that article? Corum mentions
several times that everything he reduces to the simple formulas applies
only to quarter-wave resonance conditions.

Look at the author's highlight between equations 31 and 32. Look at the
discussion near equation 47. Look at the discussion following equation
60. Read the entire discussion in section 5.

Note that he does not say the characteristic impedance is a constant
that can be deduced from resonance conditions and then applied to
operating conditions. In fact, he says exactly the opposite.

"It is worth noting that, for a helical anisotropic wave guide, the
effective characteristic impedance is not merely a function of the
geometrical configuration of the conductors (as it would be for lossless
TEM coaxial cables and twin-lead transmission lines), but it is also a
function of the excitation frequency."

I have no comment on the validity of the Corum analysis. He makes a lot
of approximations and simplifications which may or may not be completely
correct. However, it is clear that you are mis-quoting him.

73,
Gene
W4SZ

The Corum duo model their Tesla coil as "an isotropically conducting
cylindrical boundary." Later, they call it a "helically disposed surface
waveguide." Later, they write, "Further, the Tesla coil passes to a
conventional lumped element inductor as the helix is electrically
shortened." Do the first two quotes resemble a description of a
typical ham antenna loading coil? Has anybody here used a Tesla coil
to load an antenna? The Corums also state in one part of their paper
that their method of analysis is "fraught with danger." Indeed.
Cecil's misuse of the formulas certainly proves that.
Many people over the years have done just fine loading their antennas
with lumped inductors. There's no need to put a "helically disposed
surface waveguide" on a mobile antenna, and if someone thinks that
modeling a coil as "an isotropically conducting cylindrical boundary"
actually turns that coil into an isotropically conducting cylindrical
boundary, that someone should seek help.
73,
Tom Donaly, KA6RUH- Hide quoted text -

- Show quoted text -

Tom,
May I point out that a Tesla coil is an "antenna" that does not
conform
to Maxwells laws with respect to the adherance to the LC ratio.
The LC ratio is out of balance such that the capacitor is not
of the correct size to store and then return the imposed energy from
the inductive heavy coil which is visually seen as resulting in a
spark.
Regards
Art

Tom,
May I point out that a Tesla coil is an "antenna" that does not
conform
to Maxwells laws with respect to the adherance to the LC ratio.
The LC ratio is out of balance such that the capacitor is not
of the correct size to store and then return the imposed energy from
the inductive heavy coil which is visually seen as resulting in a
spark.
Regards
Art

Huh...

tesla coils follow all of Maxwells equations quite nicely. Paul
Nicholson did some very nice analysis on this a few years back,
published at a link previously posted.

They're two coupled LC resonant circuits, with the coupling adjusted to
around k=0.2. There are higher order systems with 3 or more resonators,
as well (called Magnifiers in the TC world)

The challenge in spark making is choosing appropriate operating
parameters (coupling, radius of curvature, topload capacitance, etc.) to
optimally promote spark growth.

On 30 Nov, 11:01, Jim Lux wrote:
Tom,
May I point out that a Tesla coil is an "antenna" that does not
conform
to Maxwells laws with respect to the adherance to the LC ratio.
The LC ratio is out of balance such that the capacitor is not
of the correct size to store and then return the imposed energy from
the inductive heavy coil which is visually seen as resulting in a
spark.
Regards
Art

Huh...

tesla coils follow all of Maxwells equations quite nicely. Paul
Nicholson did some very nice analysis on this a few years back,
published at a link previously posted.

They're two coupled LC resonant circuits, with the coupling adjusted to
around k=0.2. There are higher order systems with 3 or more resonators,
as well (called Magnifiers in the TC world)

The challenge in spark making is choosing appropriate operating
parameters (coupling, radius of curvature, topload capacitance, etc.) to
optimally promote spark growth.

Let me make it quite clear. I was referring to a single coil and
not the feeding arrangement. I used that as a refernce only in
conjunction
with the subject of antenna coils. This single coil, tho resonant,
does
not meet the requirements that Maxwell demands ie equilibrium.
Further study of that coil will show the effect of ground beyond the
coil
which thus involves the system as well as the associated coil for feed
coupling.
Regards
Art Unwin..KB9MZ....xg