Velocity Factor and resonant frequency
 

wrote:
TE, TM, or TEM a small loading coil cannot behave very much like a
transmission line.

We are not discussing small coils, Tom. We are discussing big
honking 75m bugcatcher coils. Why do you guys always retreat
from the real world into the area of "small" coils?

If you read the Corum paper carefully, you see he clearly states it is
an approximation or solution for a coil under the very special
condition of being self-resonant.

False. He clearly states that the VF and Z0 were established at
the self-resonant frequency and that those values hold as long
as the coil pitch, coil diameter, and frequency remain unchanged.
That's exactly what I have done using EZNEC models.

He is working on Tesla coils, not loading coils.

The first words in the title are, "RF Coils, ...". Figure 2
looks just like a 75m bugcatcher system with a top hat. A
75m bugcatcher coil is a helical resonator that brings the
antenna system into resonance.

He has a litmus test for RF coils. If the coil dimensions
pass the litmus test, then his VF and Z0 equations are known
to be valid within 10%. A 75m bugcatcher coil passes that
litmus test by a 100% margin.

A self-resonant coil is 90 degrees long. Dr. Corum says the
lumped circuit model doesn't work until the coil is trimmed
down to 0.167 of that length. Seems you have proven that to
be true.

Notice also how Cecil misquotes to make a point. The Vf I measured on
80 meters for a large bug-catcher style coil was actually .5 compared
to spatial length, not 1.0

Sorry, my memory was faulty on that one but 0.5 is still 1000%
different from the value predicted by Dr. Corum's VF equation
and flies in the face of known technical facts about coils.

On the other hand Cecil has measured virtually nothing, Yuri has
measured nothing, ...

Which is better, Tom. Valid science or invalid measurements? You
still haven't answered my question as to why you don't just
assert that a 1/4WL monopole is zero degrees long since there is
zero degrees of phase shift in the standing wave current phase
from end to end in the antenna. Heck, you can even prove that
a 1/2WL thin-wire dipole is zero degrees long using the same
measurement techniques that you used on a coil.

... and Harrison probably hasn't even owned a bug catcher
coil being a technician class license holder.

Instead of belittling his ham license, how about you compare
your technical degrees to "Harrison's"?
--
73, Cecil http://www.qsl.net/w5dxp

Velocity Factor and resonant frequency
 

Velocity Factor and resonant frequency
 

Cecil Moore wrote:

wrote:

TE, TM, or TEM a small loading coil cannot behave very much like a
transmission line.


We are not discussing small coils, Tom. We are discussing big
honking 75m bugcatcher coils. Why do you guys always retreat
from the real world into the area of "small" coils?

If you read the Corum paper carefully, you see he clearly states it is
an approximation or solution for a coil under the very special
condition of being self-resonant.


False. He clearly states that the VF and Z0 were established at
the self-resonant frequency and that those values hold as long
as the coil pitch, coil diameter, and frequency remain unchanged.
That's exactly what I have done using EZNEC models.

He is working on Tesla coils, not loading coils.


The first words in the title are, "RF Coils, ...". Figure 2
looks just like a 75m bugcatcher system with a top hat. A
75m bugcatcher coil is a helical resonator that brings the
antenna system into resonance.

He has a litmus test for RF coils. If the coil dimensions
pass the litmus test, then his VF and Z0 equations are known
to be valid within 10%. A 75m bugcatcher coil passes that
litmus test by a 100% margin.

A self-resonant coil is 90 degrees long. Dr. Corum says the
lumped circuit model doesn't work until the coil is trimmed
down to 0.167 of that length. Seems you have proven that to
be true.

Notice also how Cecil misquotes to make a point. The Vf I measured on
80 meters for a large bug-catcher style coil was actually .5 compared
to spatial length, not 1.0


Sorry, my memory was faulty on that one but 0.5 is still 1000%
different from the value predicted by Dr. Corum's VF equation
and flies in the face of known technical facts about coils.

On the other hand Cecil has measured virtually nothing, Yuri has
measured nothing, ...


Which is better, Tom. Valid science or invalid measurements? You
still haven't answered my question as to why you don't just
assert that a 1/4WL monopole is zero degrees long since there is
zero degrees of phase shift in the standing wave current phase
from end to end in the antenna. Heck, you can even prove that
a 1/2WL thin-wire dipole is zero degrees long using the same
measurement techniques that you used on a coil.

... and Harrison probably hasn't even owned a bug catcher
coil being a technician class license holder.


Instead of belittling his ham license, how about you compare
your technical degrees to "Harrison's"?

Tom sure hit the nail on the head this time, didn't he, Cecil.
When are you guys going to do your own experiments and
measurements. Yuri at least threatens to do them. You just
use a fast mouth and a few hick rhetorical techniques to get
someone - anyone - to go along with you. A man can justify just
about anything with his mouth, including CFA antennas and their
kin, but providing repeatable experiments and measurements
is something else again... ain't it.
73,
Tom Donaly, KA6RUH

Velocity Factor and resonant frequency
 

On Sun, 30 Apr 2006 12:20:10 GMT, Cecil Moore
wrote:

A 75m bugcatcher coil passes that litmus test by a 100% margin.

That would be pretty poor litmus! Acceptable error has increased from
±59% to ±100%

So as to conserve thread length, please choose excuse by number:
1. Typing error;
2. Poor eye cite;
3. MENSa decreptis;
4. Xerox copier jam;
5. Rhetorical answer.

Velocity Factor and resonant frequency
 

Tom Donaly wrote:
Everyone wants to use the most unreliable instrument they possess, their
brain, to measure natural phenomena. The Corum boys wrote an
entertaining paper that makes use of what is evidently an old
technique for explaining helical behavior in the microwave range
to make a point about self-resonant coils being superior to
coil-capacitor combinations for producing long sparks in
Tesla coils. Taken literally, the paper misses the magic
ingredient of validation by experimentation.

Drs. Corum have published many papers which include experiments
and measurements. The above referenced paper is the technical
summation of theory and measurements. The other paper that I
quoted contains all the experimental measurements that you could
ask for. Enjoy. It is at:

http://www.ttr.com/corum/index.htm
--
73, Cecil http://www.qsl.net/w5dxp

Velocity Factor and resonant frequency
 

Tom Donaly wrote:
When are you guys going to do your own experiments and
measurements.

I've already done them and reported them here, Tom. Here's
the procedure again.

1. Take a sample coil and measure the 1/4WL self resonant
frequency over my GMC pickup ground plane.

2. Keeping everything else the same, cut off half of the
above coil.

3. Add enough straight wire as a stinger to bring the
antenna system back to resonance at the previous self-
resonant frequency.

4. The delay through half the coil at the self resonant
frequency of the whole coil, is known to be 45 degrees.
The stinger is 11 degrees long. The impedance discontinuity
between the coil and the stinger provides the other 34
degrees of phase shift.

Both sides of the argument assumed only two phase shifts
were involved. Both sides were wrong. The third phase
shift is obvious once you know it exists and is perfectly
visible on a Smith Chart. When the impedance at Z01 is
1.0 on the Smith Chart and transforms to 9.0 on the Smith
Chart for Z02, that's obviously a large phase shift.

Two years ago, both sides agreed that the stinger was
about 11 degrees of the antenna.

1. Side 1 said that the base loading coil acted as a
purely lumped inductance providing 79 degrees of phase
shift essentially at a point.

2. Side 2 said that the base loading coil provided a
79 degree delay like the delay in a transmission line,
which was the source of the 79 degree phase shift.

At that time, both sides were unaware of the phase
shift occuring at the impedance discontinuity point.

Now we know that both sides were partially right and
partially wrong. As side 1 said, there is an abrupt
phase shift at a point. As side 2 said, there is a
delay through the coil. The truth seems to be just
about in the middle of the two previous arguments
which should make both sides happy.

There are tens of degrees of delay through the coil.

There are tens of degrees of abrupt phase shift at
the coil to stinger impedance discontinuity.

Both sides were equally right and equally wrong. Who
won? Both sides. Who lost? Both sides. This is the
invariable result when both sides are forced off the
rails by reality.
--
73, Cecil http://www.qsl.net/w5dxp

Velocity Factor and resonant frequency
 

Tom, W8JI wrote:
"--Harrison probably hasn`t even owned a bug catcher coil being a
technician class license holder."

You don`t need to own things to understand them.

I have a technician class radio amateur license renewed after its
initial ten-hear term. My First FCC license was a 1st class
radiotelephone license passed on my first attempt at the test in the
Houston FCC Office in early 1949. Shortly thereafter I got a call from
a Houston broadcaster that resulted in employment at a plant housing two
AM atations which shared a common antenna system. From there I went to
work in medium-wave and shortwave broadcasting stations for a dozen
years, got several college degrees including a BSEE.

I took a job with a petrochemical conglomerate which called me in 1960
saying that it intended to "automate" its operations and they thought I
might be helpful. In their employment, I installed low-frequency
aircraft beacons, 6-GHz microwave, shortwave AM, FM, and SSB. Installed
telephones and electric power plants.

The conglomerate found, produced, transported, traded, refined.
manufactured and marketed oil and gas and products made from them. That
was only a start. The company mined materials from the earth and from
the sea bottom. It farmed, manufactured tractors and automobile
components and tools. It built nuclear submarines, surface ships,
natural gas tankers which consumed their own boil off, and it laid pipe
across Canada and the U.S.A. It even consulted for other countries on
the best ways to install and operate pipelines. I worked with a handfull
of others for the subsidiary that did that for awhile. The company sold
insurance because insurance companies have mush of the capital, and for
a similar reason it bought and operated banks.. We made PVC and other
chemical products. I worked in many of the company`s divisions when they
asked for my services. We eventually put the pipeline divison under
computer control from from Houston dispatcher`s office. Hundred of
remotes were involved between Maine and Mexico.

I`ve wound plenty of coils and tuned many mobile whips with my own
hands. We used HF radios from Ecuador to Tierra del Fuego. I`ve worked
on HF and VHF radios in the company`s aircraft. When I retired in 1986,
I was manager of telecommunications.

Best regards, Richard Harrison, KB5WZI

Velocity Factor and resonant frequency
 

Cecil Moore wrote:

Tom Donaly wrote:

Everyone wants to use the most unreliable instrument they possess, their
brain, to measure natural phenomena. The Corum boys wrote an
entertaining paper that makes use of what is evidently an old
technique for explaining helical behavior in the microwave range
to make a point about self-resonant coils being superior to
coil-capacitor combinations for producing long sparks in
Tesla coils. Taken literally, the paper misses the magic
ingredient of validation by experimentation.


Drs. Corum have published many papers which include experiments
and measurements. The above referenced paper is the technical
summation of theory and measurements. The other paper that I
quoted contains all the experimental measurements that you could
ask for. Enjoy. It is at:

http://www.ttr.com/corum/index.htm

That's your idea of careful experimentation is it? First start out
with a controversy that doesn't exist, then prove what everyone knows
in the first place. So what part of the experimentation addresses
the "sheath helix" model of their Tesla coil, Cecil?
73,
Tom Donaly, KA6RUH

Velocity Factor and resonant frequency
 

Cecil Moore wrote:

Tom Donaly wrote:

When are you guys going to do your own experiments and
measurements.


I've already done them and reported them here, Tom. Here's
the procedure again.

1. Take a sample coil and measure the 1/4WL self resonant
frequency over my GMC pickup ground plane.

2. Keeping everything else the same, cut off half of the
above coil.

3. Add enough straight wire as a stinger to bring the
antenna system back to resonance at the previous self-
resonant frequency.

4. The delay through half the coil at the self resonant
frequency of the whole coil, is known to be 45 degrees.
The stinger is 11 degrees long. The impedance discontinuity
between the coil and the stinger provides the other 34
degrees of phase shift.

Both sides of the argument assumed only two phase shifts
were involved. Both sides were wrong. The third phase
shift is obvious once you know it exists and is perfectly
visible on a Smith Chart. When the impedance at Z01 is
1.0 on the Smith Chart and transforms to 9.0 on the Smith
Chart for Z02, that's obviously a large phase shift.

Two years ago, both sides agreed that the stinger was
about 11 degrees of the antenna.

1. Side 1 said that the base loading coil acted as a
purely lumped inductance providing 79 degrees of phase
shift essentially at a point.

2. Side 2 said that the base loading coil provided a
79 degree delay like the delay in a transmission line,
which was the source of the 79 degree phase shift.

At that time, both sides were unaware of the phase
shift occuring at the impedance discontinuity point.

Now we know that both sides were partially right and
partially wrong. As side 1 said, there is an abrupt
phase shift at a point. As side 2 said, there is a
delay through the coil. The truth seems to be just
about in the middle of the two previous arguments
which should make both sides happy.

There are tens of degrees of delay through the coil.

There are tens of degrees of abrupt phase shift at
the coil to stinger impedance discontinuity.

Both sides were equally right and equally wrong. Who
won? Both sides. Who lost? Both sides. This is the
invariable result when both sides are forced off the
rails by reality.

The only problem with that, Cecil, is that in neither the
coil nor the inductor do you have a uniform Z0. Since the
capacitance per unit length is a variable, so is Z0 which
is dependant on it. You've been sucked into Reg's
practice of assuming an average Z0 in order to do
calculations, but in your case it won't work because
you have to posit two distinct Z0s to have your impedance
boundary. In actuality, there's a constant change in Z0 up
and down both the stinger and the coil so your idea is a
bust. By the way, if you or the Corum boys really want a
transmission line resonator for your antenna/Teslacoils
you should switch to a helical resonator, the kind ensconced
in a can. Of course, the sparks will be disappointing, but the
theory will work better.
73,
Tom Donaly, KA6RUH

Velocity Factor and resonant frequency
 

Tom Donaly wrote:
In actuality, there's a constant change in Z0 up
and down both the stinger and the coil so your idea is a
bust.

The gradual change in Z0 really doesn't matter. What matters
is the *abrupt* change in Z0's at the coil to stinger impedance
discontinuity. That's where the abrupt phase shift occurs.
--
73, Cecil http://www.qsl.net/w5dxp