Current through coils
 

Roy Lewallen wrote:
But in a tightly wound inductor, a field created by the current in one
turn is coupled almost instantly to all the other turns ...

"All the other turns"? Here's what Jim Lux, W6RMK, had to say
about that:

"For inductance the signficant thing is that the magnetic field
of one segment pretty much links to the adjacent segments, and
less so for the rest."

Less to the 3rd, less than that to the 4th, even less than that
to the 5th. What do you think it might be by the time it gets
to the 80th turn on Tom's coil? Seems that we can assume that
the linkage between coil #1 and coil #80 is negligible.

Once again it's necessary to point out that I'm speaking here of an
inductor which has very good coupling between turns and minimal field
leakage or radiation, ...

So was W6RMK.

There's no magic transition point.

Indeed there isn't. I repeat, in case your didn't understand -
indeed there isn't. So you can discard your magic lumped-
circuit model for a system containing reflections.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Richard Clark wrote:

Cecil Moore wrote:
Those two subjects were in different paragraphs and completely unrelated.

'xactly my point.

So if your point and my point are exactly the same, what is
the point in disagreeing?
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

On Mon, 13 Mar 2006 20:47:53 GMT, Cecil Moore wrote:
So if your point and my point are exactly the same, what is
the point in disagreeing?
It doesn't respond to John's question. Glad you have no dispute.

Now we can proceed to your interpretation of what John apparently (to
you) meant by his question, and how you answered THAT.

Current through coils
 

Cecil Moore wrote:
I have
hardly any idea how they used a "fiber optic probe" to make
their measurements. I suspect they superposed local RF phasors
and used a fiber optic system to report the results. That's
what I would do.

Make sure you set those "superposed local RF phasors" on stun before you
make the measurement. Otherwise you might hurt someone.

73,
Gene
W4SZ

Current through coils
 

Gene Fuller wrote:
Cecil Moore wrote:
I have
hardly any idea how they used a "fiber optic probe" to make
their measurements. I suspect they superposed local RF phasors
and used a fiber optic system to report the results. That's
what I would do.

Make sure you set those "superposed local RF phasors" on stun before you
make the measurement. Otherwise you might hurt someone.


The current measurements Roy and I independently made using different
equipment and antennas on resonant antennas aren't valid, according to
Cecil.

The measurements I made on multiple inductors on the test bench in a
non-resonant system terminated in a load resistor aren't valid either,
according to Cecil.

What do all these measurements have in common?

The phasors were on stun. ;-)

Current through coils
 

David G. Nagel wrote:
John Popelish wrote:

The tantalizing part from my perspective is this:

"The measurements were made with carefully designed fiberoptic probes
that were specifically designed to avoid perturbing the magnetic and
electric fields."

I would like to read a full description of this instrumentation.



Like many others I don't know everything. In line with reducing my
ignorance could you amplify on how the phenomena is measured with a
"fiber optic probe". What type of transducer is used to convert energy
of an electrical nature to energy of an optical nature with out
"perturbing the magnetic and electric fields".

I wish I could, but this is the first I have heard of such
instrumentation. That is why I would like to read more about it.

Current through coils
 

Cecil Moore wrote:
John Popelish wrote:

I also note that the opening statement:

"For closewound coils, with length to diameter ratios around 5:1, a
series of fairly careful measurements have been made with the coils
arranged vertically above a ground plane, fed at the base, with a
capacitive load on the other end, and the driving frequency arranged
to be at the resonant frequency of the whole assembly."

This definitely specifies only a single frequency for the test.


Yes, a 75m mobile base-loaded antenna is a single frequency
antenna. Why are you surprised? Those guys have figured out
something that I haven't, probably because they have better
tools at their disposal than I do. They seem to have a 1%
accurate model at frequencies other than the self-resonant
frequency. I, OTOH, am only sure of my accuracy at the
self-resonant frequency due to the limited tools at my
disposal.

So I don't see how this reference
supports your claim that measuring the delay at resonance tells you
the delay at other frequencies. It also contradicts your claim about
how a standing wave makes it difficult to measure the current delay
through the coil. What have I missed?


You missed the complete point, John.
(snip)

I don't think so. Your claim is that one can use a resonant condition
to find the current delay at that frequency, and then, assume that
that delay holds for all other, lower frequencies. I am skeptical
that this is the case for any device that is not inherently a constant
delay device. I think you are assuming your conclusion. You may be
right, but you can't prove it by assuming it. You have to demonstrate
it, (or find a reference where someone else does that) to be
persuasive. I am rooting for you, because this would be a handy
technique, but I am still skeptical that it is generally applicable.

Current through coils
 

It's my policy to keep all email confidential.

However, Cecil persists in sending me unwelcome email. I've requested
several times, first politely then bluntly, that he stop sending it, but
he ignores my requests and persists. I assume this is driven by the same
compulsion that keeps him promoting his alternate theories.

Because this email comes after repeated requests that it not be sent, I
don't feel bound to give it the same level of privilege as all other
email and keep it private. I believe it's relevant to the discussion at
hand on this group, so I'll share it here, verbatim and without editing.
The subject is "Can't resist".

---- Beginning of quote ----

Sorry, Roy, I forgot to delete your email address from
my email address file.

When your house of cards based on out and out lying comes
tumbling down, exactly how are you going to handle the
obvious deliberate attempt at misinformation that you
and Tom have been distributing to the unwashed masses
for so many years? Did you think you would never get
caught in your lies during your lifetime or what? After
20 years of evidence to the contrary, you can hardly
plead ignorance.
--
no 73 for the "gobbledygook" guy, Cecil, W5DXP

---- End of quote ----

This is from the person who so loudly complains about people making
personal attacks in place of reasoned arguments. I've done my best to
explain basic theory, and even spent a day carefully constructing and
making measurements and honestly reporting the results. I'll continue to
do my best to present factual information in spite of these juvenile
attacks, and will try my best to remain objective, although it's awfully
hard sometimes in an environment that brings responses like this email
typifies. Anyone who doesn't want to read what I post should add me to
his newsgroup reader filter, as I did Cecil to mine two years ago. Those
who do read what I post should know that I have absolutely no reason nor
desire to mislead anyone in any way.

Roy Lewallen, W7EL

Current through coils
 

John Popelish wrote:

I wish I could, but this is the first I have heard of such
instrumentation. That is why I would like to read more about it.

Hopefully the poster mentioning the optical probe will explain a bit
more. But I recall seeing optically coupled instrumentation used in an
EMI screen room to couple signals in and out. To my knowledge, though,
the probes themselves were conventional, and fiber optics were used only
to replace connecting wires.

Roy Lewallen, W7EL

Current through coils
 

Roy Lewallen wrote:
John Popelish wrote:


I wish I could, but this is the first I have heard of such
instrumentation. That is why I would like to read more about it.


Hopefully the poster mentioning the optical probe will explain a bit
more. But I recall seeing optically coupled instrumentation used in an
EMI screen room to couple signals in and out. To my knowledge, though,
the probes themselves were conventional, and fiber optics were used only
to replace connecting wires.

Roy Lewallen, W7EL


Roy and John;

The fiber optic leads are used in the experiment mentioned in the story
linked by the URL that was recently mentioned in this thread. I think
the whole thing is hilarious and was especially struck by the use of
glass fiber to measure an electrical/magnet phenominum with no
indication how the measurement is made. Sort of in line with someone's
line of thinking in this thread.

Dave N