On 29 Nov, 09:11, Jim Kelley wrote:
Cecil Moore wrote:
W8JI's mistake was using standing wave current to try
to measure that delay.

It's not at all apparent that that was his mistake.

Even though the delay changes with frequency,
it is highly unlikely to drop from 90 degrees to 4.5
degrees in a few MHz.

Any phase delay given in degrees would of course vary as function of
angular frequency independent of any systematic effect simply by
virtue of the fact that the amount of time per period varies with
frequency while the number of degrees per period obviously do not.

Over the range of a few octaves, propagation delay on the other hand
does not vary to any significant extent as a function of frequency.
Ostensibly, it should be equal to sqrt(LC) series L, shunt C.
e.g.

http://www.rhombus-ind.com/dlcat/app1_pas.pdf

In order to either validate or invalidate claims, one must do at least
two things. First make verifyable and repeatable measurements.
Second, show how those measurements are supported by the underlying
principles, and are predicted by the associated mathematics. Without
those things, you may as well go shout it at cars.

Actually, it is an exercise in the physics of reality.
A 3nS delay through a 100 uH coil is the real "exercise
in philosophical fantasy" and obviously impossible.

The display on Tom's web page appears to be set for 100ns per
division. The delay between cursor 1 and cursor 2 is 486.43 nS, and
the position of cursor 1 appears to be arbitrarily set. The 3nS
measurement would be at ~0.3% of full scale - not normally the scale
one would employ to make such a measurement. Lacking any sort of
description of the stimulus or of the instrument, it's not clear to me
what W8JI's test unit is actually measuring. But at least he measured
something and isn't shouting at cars about it.

73, ac6xg

Darn it! why haven't you spoken up before with respect to slow wave
properties and the parameters required to make them? You could have
helped a lot in my threads on Gaussian antennas by cutting off old
wive tales.
Art KB9MZ

Tom Donaly wrote:
Do you really believe that an antenna + loading coil has
to be a quarter wave long to resonate?

Note: I am NOT talking about *physical* lengths.
The phase shift from feedpoint to tip has to be
*electrically 90 degrees* so the answer is yes.
For a base-loaded mobile antenna, the sum of the
phase shifts a

PS1. The phase shift through the loading coil.
PS2. The phase shift at the coil to stinger junction.
PS3. The phase shift in the stinger.

PS1 + PS2 + PS3 = 90 degrees.

In a typical 75m base-loaded mobile antenna, PS1
may be about 40 degrees, PS2 about 40 degrees, and
PS3 about 10 degrees.

PS2 is a freebie lossless phase shift compliments of
Mother Nature caused by the impedance discontinuity
between the coil and the stinger. If that phase shift
can be maximized, it should add to antenna efficiency.
--
73, Cecil http://www.w5dxp.com

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

Cecil Moore wrote:

It is exactly my point that
there is no phase shift associated with standing-
wave current in a coil or in a wire so it CANNOT
be used to "measure" phase shift.

On the other hand, the standing wave, which is nothing more than the
superposition of the forward and reflected waves, easily demonstrates
the effect the propagation delay has on the forward and reflected waves.

There is NO
phase information in the current used for the
W8JI and W7EL measurements.

That certainly can't be said about your measurements. Perhaps that's
why you're so reluctant to make any? :-)

They both apparently
thought they were measuring traveling-wave currents
when the currents were actually overwhelmingly
standing-wave currents.

Don't flatter yourself, Cecil. You're not that much smarter than
everybody else in the room.

73, ac6xg

Tom Donaly wrote:
Your problem is
that you've become so enamored of your little reflection theory that
you insist that only a set of transmission lines 90 degrees in total
length can resonate. Too bad your education isn't complete or you'd know
this isn't so.

Obviously, I am not talking about *physical* length.
The "90 degrees" is the total *electrical* length.
Please tell us how you get resonance out of a stub
that is *electrically* 45 degrees long? No resistive
or reactive components are allowed. Here's your
chance to nail me to the wall.
--
73, Cecil http://www.w5dxp.com

Jim Kelley wrote:
On the other hand, the standing wave, which is nothing more than the
superposition of the forward and reflected waves, easily demonstrates
the effect the propagation delay has on the forward and reflected waves.

But the phase information in the forward and reflected
waves does not appear as phase information in the standing
wave. The forward and reflected phase information appears
in the standing-wave amplitude. That is another error that
W8JI and W7EL made. The different amplitudes of standing-
wave current at each end of a coil is NOT caused by losses
and radiation. It is caused by superposition of the forward
and reflected waves. It would still happen if there was zero
losses and zero radiation.

Don't flatter yourself, Cecil. You're not that much smarter than
everybody else in the room.

Not smarter - just more observant. I saw something that
nobody else was looking for. It is only closed minds that
are the problem now.
--
73, Cecil http://www.w5dxp.com

On Thu, 29 Nov 2007 14:18:22 -0600, Cecil Moore
wrote:

I should think that many hams have things that can measure 3 ns (1000mm
light time), particularly in a repetitive system. That's one cycle at
300 MHz, or 36 degrees at 30 MHz.

The referenced W8JI 3 nS "measurement" was the delay
in a 2' dia, 100 T, 10" long loading coil on 4 MHz,
i.e. 4.5 degrees.

Jim's point is that it can be done!

Your point is that you can't do it?

Asking for a handout, and escaping work is called mooching.

Cecil Moore wrote:
Gene Fuller wrote:
Second, your analysis is utter rot! Are you suggesting that if the
coil can be made resonant at some frequency, and then you cut it in
half, that it still behaves the same?

No, it behaves approximately like half of the original
coil tending to have approximately the same Z0 and VF as
the original coil. The phase shift through the coil will
tend to be approximately 1/2 of the original phase shift -
not exact because of end effects.

Let's say we have a 1/4WL helical antenna with an obvious
phase shift of 90 degrees. If we cut that helical in half,
it is likely to have a phase shift of approximately 45
degrees, nowhere near the 4.5 degrees that W8JI has
"measured".

If we add a stinger to the above half-coil, we will have
a base-loaded antenna. The phase shift will be relatively
close to 45 degrees at the same frequency. The stinger
contributes another few degrees. The impedance discontinuity
between the coil and stinger contributes the rest of the
90 degrees of electrical length.

Cecil,

It appears you missed the primary message of the Corum article. He is
completely denying the simple concept you wrote above. He argues that
there is a very special effect near resonance. You cannot simply cut the
coil in half and expect the same behavior.

Frankly, I have little interest in Tesla coils, and I don't know or care
if Corum is right or wrong. I do believe, however, that it is a bit
careless for you to pick and choose equations from the article, ignore
the caveats, and then go ahead and misuse those equations.

73,
Gene
W4SZ

I see Cecil is still using misdirection, that old but reliable trick of
illusionists, to try and divert attention away from the flaws in his
imaginative theories. Have patience. Even he will tire of it after a
while, and get back to his waves of average power that bounce off each
other when they collide.

Roy Lewallen, W7EL

Jim Kelley wrote:
Cecil Moore wrote:

It is exactly my point that
there is no phase shift associated with standing-
wave current in a coil or in a wire so it CANNOT
be used to "measure" phase shift.

On the other hand, the standing wave, which is nothing more than the
superposition of the forward and reflected waves, easily demonstrates
the effect the propagation delay has on the forward and reflected waves.

There is NO
phase information in the current used for the
W8JI and W7EL measurements.

That certainly can't be said about your measurements. Perhaps that's
why you're so reluctant to make any? :-)

They both apparently
thought they were measuring traveling-wave currents
when the currents were actually overwhelmingly
standing-wave currents.

Don't flatter yourself, Cecil. You're not that much smarter than
everybody else in the room.

73, ac6xg

Cecil Moore wrote:

Don't flatter yourself, Cecil. You're not that much smarter than
everybody else in the room.


Not smarter - just more observant. I saw something that
nobody else was looking for.

Yes. Seek and ye shall find.

It is only closed minds that
are the problem now.

A perspective which apparently shifts depending on which side of the
room you happen to be standing.

73, ac6xg