K7ITM wrote:
Yes, some time earlier today than that exchange, I posted elsewhere in
this thread a specific circuit, complete with values, how the same
thing is easily accomplished with the infamous ideal lumped components.
No standing waves need apply. But of course if one used distributed
reactances, one could easily get the same effect, and the analysis can
easily be done w/o any reference to standing or travelling waves.

How about the phase shift?
--
73, Cecil http://www.qsl.net/w5dxp

wrote:
What it is NOT possible to do is make a coil change current without
that third path to the outside world. Standing waves will not do it,
missing antenna degrees will not do it.

That's a really strange thing to say, Tom. It happens all the time
inside a piece of coax with reflections. There's no third path to
the outside world, yet the standing waves inside a piece of coax
certainly cause the current to change.
--
73, Cecil http://www.qsl.net/w5dxp

Gene Fuller wrote:
I gave you a very specific reference to demonstrate your supposition was
incorrect. You came back with nothing but, "Because I say so." You have
not offered one shred of backing for your constant Vf argument.

Where the heck have you been? The equation for VF is equation (32)

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

Just before that equation for VF is a geometry test for the
coil in question. A 75m bugcatcher coil passes that test.

The velocity factor equation contains helix diameter, turns
per unit length, and wavelength. If we keep those three
quantities constant, the VF of a coil should remain constant
while varying the length of the coil.

The problem encountered previously was we kept the coil length
constant while varying the frequency. That does change the VF.
But this time we are keeping frequency constant.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil,

Why don't you go back and re-read that paper carefully. Pay particular
attention to the part where the author says, with emphasis, that the
magic formula only works when the coil is near or at resonance.

Your extension to arbitrarily lower frequencies is pure nonsense.

I guess you did not read my complete message. I pointed out the exact
location in the paper where this limitation is explained.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

I gave you a very specific reference to demonstrate your supposition
was incorrect. You came back with nothing but, "Because I say so." You
have not offered one shred of backing for your constant Vf argument.


Where the heck have you been? The equation for VF is equation (32)

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

Just before that equation for VF is a geometry test for the
coil in question. A 75m bugcatcher coil passes that test.

The velocity factor equation contains helix diameter, turns
per unit length, and wavelength. If we keep those three
quantities constant, the VF of a coil should remain constant
while varying the length of the coil.

The problem encountered previously was we kept the coil length
constant while varying the frequency. That does change the VF.
But this time we are keeping frequency constant.

Gene Fuller wrote:
Why don't you go back and re-read that paper carefully. Pay particular
attention to the part where the author says, with emphasis, that the
magic formula only works when the coil is near or at resonance.

A 75m bugcatcher coil is self resonant at 6.6 MHz. That's
near 4 MHz. Where is all your irrationality coming from?
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Gene Fuller wrote:

Why don't you go back and re-read that paper carefully. Pay particular
attention to the part where the author says, with emphasis, that the
magic formula only works when the coil is near or at resonance.


A 75m bugcatcher coil is self resonant at 6.6 MHz. That's
near 4 MHz. Where is all your irrationality coming from?

4 Mhz is not 6.6 Mhz. You're stretching the truth again, Cecil.
Gene is right. Why not just give up. You're not going
to make anything true just by repeating it over and over again.
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:
Gene Fuller wrote:

Why don't you go back and re-read that paper carefully. Pay particular
attention to the part where the author says, with emphasis, that the
magic formula only works when the coil is near or at resonance.


A 75m bugcatcher coil is self resonant at 6.6 MHz. That's
near 4 MHz. Where is all your irrationality coming from?


Cecil,

I guess you can't keep up with your fairy tales.

The exact quote from your message on April 11, at 9:57 am is copied
below. I don't see anything about a bugcatcher coil. Instead there is
some un-described coil stock that requires 37 extra turns in addition to
the starting 32 turns to achieve self-resonance at 4 MHz.

Since the Corum paper highlighted the limitation for applicability of
the magic formula it is possible he thought that the limitation might be
important. However, with your superior intellect it is fully justifiable
to go ahead and accept only those portions of his paper that support
your preconceived notions.

I suppose whatever number you determine will still fall within your 59%
standard of precision.

73,
Gene
W4SZ


[quote]

************************************************** *
Here's a more valid procedure for determining the
delay through a coil. Changing nothing except the
number of turns, add turns until the coil is self-
resonant at the frequency of use. Frequency doesn't
change. Coil diameter doesn't change. Turns per inch
doesn't change. The *ONLY* thing that changes is the
length of the coil. At self-resonance, we *know* the
longer coil is 90 degrees long.
************************************************** *

Take that same 32 turn coil and keeping everything the
same, add turns to the coil until it is self-resonant.
We haven't changed the frequency, the diameter, or the
turns per inch. All we have done is add 37 turns to the
original 32 turn coil to make the self-resonant frequency
equal to 4 MHz with 69 turns. SINCE WE HAVEN'T CHANGED
THE FREQUENCY, WE KNOW THAT THE VELOCITY FACTOR OF THE
COIL HAS NOT CHANGED.

In the velocity factor equation, the only variables are
coil diameter, turns per inch, and wavelength. NONE OF
THOSE VARIABLES ARE CHANGED ABOVE.

So we know that 69 turns makes that coil stock self-resonant
at 4 MHz. That would make the phase shift through 32 turns
equal to 42 degrees, making our above 10 degree assumption
false. 42 degrees is probably fairly close to the actual value.
The velocity factor for that coil stock calculates out to
be 0.023 on 4 MHz.

[end quote]

Tom Donaly wrote:
4 Mhz is not 6.6 Mhz.

Nobody said 4 MHz is 6.6 MHz. 4 MHz is 60% of 6.6 MHz
and is therefore near 6.6 MHz. Dr. Corum says the
lumped constant model fails at 0.04 wavelength. In his
other paper, he says if the length of the wire used to
wind the coil is 0.06 wavelength, it's time to switch
over to the distributed network model. A 75m bugcatcher
coil uses more than 0.06 wavelength of wire.

Please explain the physics behind the velocity factor
of a coil changing radically just because you cut it
in half - assuming all other parameters are kept at
the same value.

Your model is known to fail at a point but you guys
have no clue where that failure point is. You just
have faith that you will never reach the failure point.
But what if you have already reached it?
--
73, Cecil http://www.qsl.net/w5dxp

Gene Fuller wrote:

Cecil Moore wrote:
A 75m bugcatcher coil is self resonant at 6.6 MHz. That's
near 4 MHz. Where is all your irrationality coming from?

The exact quote from your message on April 11, at 9:57 am is copied
below. I don't see anything about a bugcatcher coil.

The coil being discussed is a bugcatcher coil modeled in EZNEC.

Since the Corum paper highlighted the limitation for applicability of
the magic formula it is possible he thought that the limitation might be
important.

The limitation that Dr. Corum highlighted was the failure of the
lumped circuit model when the coil is self-resonant. He says that
when we are within 17% of self-resonance, the lumped circuit model
fails. Have you anything besides faith to prove that your model
is valid within 60% of self-resonance?

Please describe the physics behind a radical change in velocity
factor (at the same frequency) when a coil is cut in half.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Gene Fuller wrote:

Cecil Moore wrote:
A 75m bugcatcher coil is self resonant at 6.6 MHz. That's
near 4 MHz. Where is all your irrationality coming from?

The exact quote from your message on April 11, at 9:57 am is copied
below. I don't see anything about a bugcatcher coil.


The coil being discussed is a bugcatcher coil modeled in EZNEC.

Since the Corum paper highlighted the limitation for applicability of
the magic formula it is possible he thought that the limitation might
be important.


The limitation that Dr. Corum highlighted was the failure of the
lumped circuit model when the coil is self-resonant. He says that
when we are within 17% of self-resonance, the lumped circuit model
fails. Have you anything besides faith to prove that your model
is valid within 60% of self-resonance?

Please describe the physics behind a radical change in velocity
factor (at the same frequency) when a coil is cut in half.

Cecil,

You have really lost it. I gave you the exact quote, and you then
proceed to talk about something else.

It appears you did not really read and understand the Corum paper
either. The portion I referred to you had nothing to say about lumped
circuits or distributed circuits. It was merely a step in the
mathematical analysis that leads to the magic formula for Vf. If you
ignore the important limitations on the math analysis it is likely that
any conclusions drawn will be incorrect.

So let's throw the topic back to you. A straight wire has a Vf near 1. A
resonant coil has a Vf of 0.01 or 0.02. So where and how does the Vf
transition occur? For a coil of one turn? For a coil with a length of
15% of the resonant length? At some other coil length? Is the Vf
transition abrupt or smooth?

You seem to understand everything about coil Vf, so these should be easy
questions for you.

73,
Gene
W4SZ