Gene Fuller wrote:
Cecil Moore wrote:

Gene Fuller wrote:
So you think adding turns to a coil is a nice linear process that
allows you to then subdivide the resonance effects according the
number of turns in each subsection?

That appears to me to be the most valid measurement that we
can make of the delay through a coil. If you have a better
way, please present it.

C'mon, you know as well as anybody that inductance of a coil tends to
increase as n-squared. Yes, there are all kinds of special cases and
correction factors.

Increasing the length of a coil or transmission line doesn't
change its velocity factor at a fixed frequency.

Adding turns and then pretending everything is nice and linear, thereby
allowing decomposition into subcomponents, is just plain silly.

Velocity factor is *nice* and linear, i.e. it is constant.

Please stop these diversions. I'm sure you are not that ignorant.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Gene Fuller wrote:
(snip)
C'mon, you know as well as anybody that inductance of a coil tends to
increase as n-squared. Yes, there are all kinds of special cases and
correction factors.


Increasing the length of a coil or transmission line doesn't
change its velocity factor at a fixed frequency.
(snip)

That is an interesting hypothesis.

How would you go about testing its validity?

(Have you heard of end effects?)

John Popelish wrote:

Cecil Moore wrote:
Increasing the length of a coil or transmission line doesn't
change its velocity factor at a fixed frequency.

That is an interesting hypothesis.

Since I know you are going to nit-pick that statement, I
probably should add "appreciably" in front of "change". :-)

How would you go about testing its validity?

The velocity factor of a piece of transmission line doesn't
change appreciably with length. The velocity factor of a
straight wire doesn't change appreciably with length.

I would think that a two wavelength coil would be approximately
twice as long as a one wavelength coil which would be
approximately twice as long as a 1/2 wavelength coil.

The equation for the velocity factor of a coil depends upon:
1. The diameter of the coil
2. The number of turns per unit length
3. The frequency

None of those factors are dependent upon the length of the
coil.

(Have you heard of end effects?)

Of course, it's the 5% difference between 468/f and
492/f. I'm not talking super accuracy here - just better
accuracy than anyone has yet measured.

It is akin to your suggestion that a coil be installed
between two current nodes and its number of degrees
calculated from that. I will try to take that same
coil that I have been talking about and use your
suggestion to see how close the results are.

However, I am preparing for a 6 state Harley road trip over
the Easter holidays and will not be back until Monday.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
(snip)
However, I am preparing for a 6 state Harley road trip over
the Easter holidays and will not be back until Monday.

I envy you. I haven't been on a decent motorcycle ride since my
12,000 mile loop from Virginia to Alaska, and back, in May, 2002.

Kill a few bugs for me.

Cecil,

I will retain the entire message below, so that I am not accused of
misattribution.

Where did you get this idea that the velocity factor is constant?
Specifically, why is the velocity factor of a resonant coil the same as
the velocity factor of a significantly shorter coil? It is pretty well
accepted that the inductance of coils does not scale linearly with the
length of the coil. Therefore any arguments about based on direct
calculation of Vf from L and C would seem to fail to support your model.

I can think of two possibilities.

The first is that you treat this entire problem as a transmission line.
Most people would accept that the velocity factor for 200 feet of RG8 is
indeed the same as the velocity factor for 100 feet of the same cable.

However, the velocity factor appears to be the crux of your latest
argument about the behavior of a loading coil. It is not exactly
acceptable technique to include the desired answer as part of the proof.


The other possibility is that you are taking the lead from one of the
Corum papers. In particular, I am referring to the paper labeled:

"TELSIKS 2001, University of Nis, Yugoslavia (September 19-21, 2001) and
MICROWAVE REVIEW"

If so, I suggest you go back and reread what was written. He
specifically says (page 4, left column) that the equations for velocity
factor that show Vf as a function of diameter, spacing, and wavelength
apply only at resonance. The exact words a

" . . . an approximation for M has been determined by Kandoian and
Sichak which is appropriate **for quarter-wave resonance** and is valid
for helices . . ."

The emphasis on quarter-wave resonance was in the original; I did not
change a thing. The remainder of the paper clearly indicates that he is
talking about coils near or at resonance. There is no extension of the
Vf equations to short non-resonant coils. Indeed, he comments several
times that his model smoothly joins with the lumped circuit model for
smaller coils. That would require a non-constant Vf.

You attempt at decomposition of a resonant coil into smaller
subcomponents simply fails.

This is not an "ignorant diversion". If you have a third method of
supporting your claim of constant Vf, let's hear it.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

Cecil Moore wrote:

Gene Fuller wrote:

So you think adding turns to a coil is a nice linear process that
allows you to then subdivide the resonance effects according the
number of turns in each subsection?


That appears to me to be the most valid measurement that we
can make of the delay through a coil. If you have a better
way, please present it.


C'mon, you know as well as anybody that inductance of a coil tends to
increase as n-squared. Yes, there are all kinds of special cases and
correction factors.


Increasing the length of a coil or transmission line doesn't
change its velocity factor at a fixed frequency.

Adding turns and then pretending everything is nice and linear,
thereby allowing decomposition into subcomponents, is just plain silly.


Velocity factor is *nice* and linear, i.e. it is constant.

Please stop these diversions. I'm sure you are not that ignorant.

Gene Fuller wrote:
I will retain the entire message below, so that I am not accused of
misattribution.

Gene, to the best of my knowledge, you have never
misattributed anything.

Where did you get this idea that the velocity factor is constant?

The equation for velocity factor includes coil diameter,
turns per inch, and wavelength. Keeping the coil diameter
constant, the turns per inch constant, and the wavelength
constant should ensure that the velocity factor is constant.

Specifically, why is the velocity factor of a resonant coil the same as
the velocity factor of a significantly shorter coil? It is pretty well
accepted that the inductance of coils does not scale linearly with the
length of the coil. Therefore any arguments about based on direct
calculation of Vf from L and C would seem to fail to support your model.

You are obviously mistaken. If you increase the L by lengthening
the coil, you have also increased the C by the same percentage.
The L and C for any unit length are the same no matter how long
the coil or transmission line is.

" . . . an approximation for M has been determined by Kandoian and
Sichak which is appropriate **for quarter-wave resonance** and is valid
for helices . . ."

Yes, but if one doesn't change the frequency or the diameter or
the turns per inch, the approximation should hold since nothing
in the VF equation changes by shortening the coil. One should be
able to shorten or lengthen the coil andmaintain the same VF.

Seems it is up to you to prove what you are saying. Please prove
that the ratio of L to C ratio of a coil changes with length. That
should be an interesting proof.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil,

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.

And it is up to ME to further prove something?

I don't think so.

73,
Gene
W4SZ


Cecil Moore wrote:
Gene Fuller wrote:

I will retain the entire message below, so that I am not accused of
misattribution.


Gene, to the best of my knowledge, you have never
misattributed anything.

Where did you get this idea that the velocity factor is constant?


The equation for velocity factor includes coil diameter,
turns per inch, and wavelength. Keeping the coil diameter
constant, the turns per inch constant, and the wavelength
constant should ensure that the velocity factor is constant.

Specifically, why is the velocity factor of a resonant coil the same
as the velocity factor of a significantly shorter coil? It is pretty
well accepted that the inductance of coils does not scale linearly
with the length of the coil. Therefore any arguments about based on
direct calculation of Vf from L and C would seem to fail to support
your model.


You are obviously mistaken. If you increase the L by lengthening
the coil, you have also increased the C by the same percentage.
The L and C for any unit length are the same no matter how long
the coil or transmission line is.

" . . . an approximation for M has been determined by Kandoian and
Sichak which is appropriate **for quarter-wave resonance** and is
valid for helices . . ."


Yes, but if one doesn't change the frequency or the diameter or
the turns per inch, the approximation should hold since nothing
in the VF equation changes by shortening the coil. One should be
able to shorten or lengthen the coil andmaintain the same VF.

Seems it is up to you to prove what you are saying. Please prove
that the ratio of L to C ratio of a coil changes with length. That
should be an interesting proof.

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.

Good Grief, Gene, can't I have a 6 day motorcycle in piece without
you saying something that is not true?
--
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.