Current across the antenna loading coil - from scratch
 

Gene Fuller wrote:
You are the expert on Vf. You assert without proof that a half-length
coil has the same Vf as the full-length resonant coil. OK, even if I
accepted that supposition, what happens at a quarter-length or at a
tenth-length? I am simply asking how the function changes between the
"known" limits of 1.0 and 0.02. You have repeatedly ducked any sort of
answer.

Seems Richard Clark has proven that it doesn't change between
the "known" limits of 1.0 and 0.02. Where did those "known"
limits come from anyway?

For a single turn coil, seems the VF would roughly be the pitch
divided by the circumference, something that would equal 1.0 only
when the pitch and circumference were equal.

For the 4 TPI, 6" diameter coil, the VF formula yields 0.02.

The pitch divided by the circumference yields 0.013.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Richard Clark wrote:
You can't change the Vf by shortening a Vf = 0.02 coil, hmmm?
Remarkable shortening of your own theory there.

It was Gene Fuller who said the coil varied between the "known"
limits of 1.0 and 0.02, not I. I just replied to Gene's posting.
You and I seem to be in agreement that the VF of the coil doesn't
change with a change in length.
--
73, Cecil http://www.qsl.net/w5dxp

Current across the antenna loading coil - from scratch
 

Cecil,

Since you have fallen back to the old "round and round the helix" model
there is little hope for agreement. It is interesting, however, that
even the Corum model for Vf at resonance is not as slow as the purely
geometric model. Must be those standing waves again.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

You are the expert on Vf. You assert without proof that a half-length
coil has the same Vf as the full-length resonant coil. OK, even if I
accepted that supposition, what happens at a quarter-length or at a
tenth-length? I am simply asking how the function changes between the
"known" limits of 1.0 and 0.02. You have repeatedly ducked any sort
of answer.


Seems Richard Clark has proven that it doesn't change between
the "known" limits of 1.0 and 0.02. Where did those "known"
limits come from anyway?

For a single turn coil, seems the VF would roughly be the pitch
divided by the circumference, something that would equal 1.0 only
when the pitch and circumference were equal.

For the 4 TPI, 6" diameter coil, the VF formula yields 0.02.

The pitch divided by the circumference yields 0.013.

Current across the antenna loading coil - from scratch
 

"Gene Fuller" wrote:

W5DXP wrote:
For the 4 TPI, 6" diameter coil, the VF formula yields 0.02.

The pitch divided by the circumference yields 0.013.

Since you have fallen back to the old "round and round the helix" model
there is little hope for agreement. It is interesting, however, that
even the Corum model for Vf at resonance is not as slow as the purely
geometric model. Must be those standing waves again.

Anyone who says the current goes "round and round the helix"
is wrong. Anyone who says the current goes like a "short circuit
through the coil is wrong."

There is NO rail "round and round the helix'! There is NO rail
"short circuit through the coil"! There is, as usual, something in
between the two rails. Looking at Fig. 1 in Dr. Corum's IEEE paper:

For a diameter/wavelength ratio of 10^-3

If the coil is1000 turns/wavelength, the VF is 0.8 which is closer
to a "short circuit through the coil" than it is to "round and round
the helix".

If the coil is 5000 turns/wavelength, the VF is 0.18 which is
closer to "round and round the helix" than it is to a "short
circuit through the coil".

The field coupling between the coils is responsible for the VF
not being as slow as the purely geometric model but there is
a practical physical limit to the number of coils that are being
coupled.

Coils are a combination of primary and secondary characteristics.
All the primary characteristics need to be taken into account. Some
of the secondary characteristics can be omitted under certain
conditions.
--
73, Cecil, W5DXP

Current across the antenna loading coil - from scratch
 

Richard Clark wrote:

Investigating Fig. 1 reveals there is no way to resolve the Vf through
shortening a coil. Only Cecil could argue there's a pony in all that
horse****, so while he's saddling himself to that mound, let's proceed
to see why his dotaged enthusiasm is ill-founded.



Wow! One of the bestest funniest paragraphs I've ever had the pleasure
of reading!

Remind me never to get on your bad side....... 8^)



Back on topic now. Was there ever any correlation between the
measurements made by Cecil and Yuri with the information and tests
performed by Tom W8JI? I had asked the question a couple times, but have
no answer yet. Maybe the message got lost.

I might be being simple here, but it seems that maybe if there was a
reasonable correlation drawn between the two instances.we could avoid
all the other junk going on.

Although getting wrapped around the axle apparently has its own
benefits to some.....

- 73 de Mike KB3EIA -

Current across the antenna loading coil - from scratch
 

"Michael Coslo" wrote:
Back on topic now. Was there ever any correlation between the
measurements made by Cecil and Yuri with the information and tests
performed by Tom W8JI? I had asked the question a couple times, but have
no answer yet. Maybe the message got lost.

Might have been when I was out of town. Except for a
single toroidal coil anomaly, all of the measurements
show a different magnitude of current at the two ends
of the coils. Most of my measurements have been at
the self-resonant frequency of a loading coil.

A 75m mobile bugcatcher coil is part of a standing wave
antenna with near-equal forward and reflected currents
flowing in opposite directions (phasors rotating in
opposite directions). As a result, the standing wave
current on the antenna has essentially the same phase
as the source current all up and down the antenna
*whether a loading coil exists or not*. Standing wave
current on a mobile antenna cannot be used to measure
phase shift or delay through a wire or a coil.

That standing wave current is of the form,
I = Io*cos(kx)*cos(wt), and cannot be used to determine
phase shift. So the major measurement mistakes were
not in the magnitudes, which are relatively easy to measure,
but in the phase-delay measurements, which were invalid.

The major conceptual mistake concerns standing waves,
not coils. It appears that some people didn't even realize
that they were dealing with a standing wave current on a
standing wave antenna.

The best estimates of actual delays through the coils seems
to come from the Dr. Corum IEEE paper where formulas
are given for the VF and Z0 of a coil. For the particular
coil being modeled in EZNEC, the VF formula yields
~0.02, or about 37 degrees for a 6" long coil on 4 MHz.
--
73, Cecil, W5DXP

Current across the antenna loading coil - from scratch
 

On Fri, 21 Apr 2006 07:39:11 GMT, Cecil Moore
wrote:

It was Gene Fuller who said the coil varied between the "known"
limits of 1.0 and 0.02, not I.
You can't change the Vf by shortening a Vf = 0.02 coil, hmmm?
Remarkable shortening of your own theory there.

Perhaps you might want to try again using real numbers. Simply
because you play the pity card of forgetfulness (blaming your reader
usually as a bluff) we will reprise the question once again:

Asked: At one length, one coil exhibits
Vf = 0.02,
reduce the coil length, what length for the SAME coil would that be
to render
Vf = 0.2
for instance?

1. We are not changing frequency;
2. we are not changing diameter/lambda
(nor in fact changing diameter OR lambda);
3. we are not changing pitch/lambda
(nor in fact changing pitch OR lambda).

SAME coil means the one being offered, and being shortened - all other
provisos stand

Current across the antenna loading coil - from scratch
 

On Fri, 21 Apr 2006 11:30:24 -0400, Michael Coslo
wrote:

Back on topic now. Was there ever any correlation between the
measurements made by Cecil and Yuri with the information and tests
performed by Tom W8JI?

Hi Mike,

Well, you have a serious problem embodied in your statement. Neither
Cecil nor Yuri made any measurements. Perhaps Yuri observed some
shrink tube that had charred while he was working power, but actually
that is a stretch (not shrink) as he "observed" this only after the
fact. You certainly have read enough correspondence to observe for
yourself that Yuri cannot describe any system fully, so saying there
were correlations can only come from a heated imagination (more
current in than coming out). If there have been any experimental
details made under observed conditions, we have to credit Tom.

73's
Richard Clark, KB7QHC

Current across the antenna loading coil - from scratch
 

My take on it is that Richard just loves yanking a chain that's
particularly easy to yank and will invariably respond in a way that
allows more yanking.

Everybody has long since agreed in principle; it's just that some
people remain buried so deeply in the forest that they can't see it for
all the trees. Or maybe it's that they are buried so deeply in the
pile that Richard was mentioning that they can't find the pony that's
been there all along to ride out on.

All this wave BS is just mathematical abstraction to 'splain what's
really going on anyway. If one is smart enough to actually get through
the math without making computational or conceptual errors, he's still
going to be lost if he doesn't relate it back to what it is that the
math is explaining. His loss; too bad.

Cheers,
Tom

(Hope I didn't let your secret out of the bag, Richard!)

Current across the antenna loading coil - from scratch
 

On 21 Apr 2006 10:40:47 -0700, "K7ITM" wrote:

My take on it is that Richard just loves yanking a chain that's
particularly easy to yank and will invariably respond in a way that
allows more yanking.

I can do that by simply asking for data.

(Hope I didn't let your secret out of the bag, Richard!)

Hi Tom,

The "secret," as you put it, is still as hidden to them as the WMD.

As you infer, it is rather all too easy to stir, but harder to
accomplish. Inferior talents prove that daily. None here see but
perhaps a tenth or less of what I've written; because as with good
technical writing, the best comedy is what is left after pruning the
excess from it.

73's
Richard Clark, KB7QHC