I'll accept your prediction. It doesn't seem to correlate with your
disagreement with Ian that the current into and out of a lumped inductor
are equal. You accused him of "mental masterbation" and being "seduced
by the steady state model" for even thinking such thoughts.

I also asked you a while back if we should expect a very small inductor
to act the same when connected at the base of an antenna as when
connected to a simple series RC or RL. Your response was that the
analysis couldn't be done using conventional circuit theory, but
required "distributed network analysis". Conventional circuit theory
predicts equal currents going in and out, so from your response I had
presumed that the fancier analysis would predict something else.

You've also stated that the current shift through the inductor should
equal the "electrical length" of the antenna "replaced" by the inductor.
In this case, the inductor is "electrically lengthening" the antenna by
either about 45 degrees, or about half that amount, depending on how you
assign the effect of the mounting arrangement.

So in the past, you've predicted no difference, something like 20 or 45
degrees phase shift, or an indeterminate amount. It's good to see you've
settled on one figure.

My inductor was placed at the antenna base because I could measure the
currents there with reasonable accuracy. The inductor size was chosen to
resonate the antenna, hopefully duplicating the situation reported by
Yuri in his quote of W9UCW's measurements.

On his web site, Yuri quoted W9UCW as measuring the currents at the ends
of a toroid mounted at the base of the antenna as being 100 mA at the
bottom and 79 at the top. You must, then, believe these measurements to
be in error.

Roy Lewallen, W7EL

Cecil Moore wrote:
Roy Lewallen wrote:

Our educations differ a great deal. Mine enabled me to give a
numerical prediction, which as anyone who has read my earlier
postings, is 1. Yours has evidently not prepared you to meet this
onerous challenge.


Roy, I have repeated a statement three or four times earlier on this
newsgroup.
My statement predicts a result of 1. Here is that statement again:

"If a loading coil is placed at a current maximum point, the current in and
out of the coil will be equal." I have been assuming that is why your coil
was placed at the current maximum point, to ensure that the currents would
be equal. Depending upon where the coil is placed, the currents in and out
of the coil can be equal, greater than, or less than.

Roy Lewallen wrote:

I'll accept your prediction. It doesn't seem to correlate with your
disagreement with Ian that the current into and out of a lumped inductor
are equal. You accused him of "mental masterbation" and being "seduced
by the steady state model" for even thinking such thoughts.

Yes, for center-loaded electrical 1/4WL mobile antennas, that is true.
You seem to be protecting the same sacred cow as Ian.

For the sixth time: If a loading coil is located at a current maximum
or current minimum point, the current into and out of the coil will
be approximately the same.

If a loading coil is located where the slope of the current is positive,
the current will actually increase through the coil.

If a loading coil is located where the slope of the current is negative,
the current will decrease through the coil. This is typical of center-
loaded mobile HF antennas.

Conventional circuit theory
predicts equal currents going in and out, so from your response I had
presumed that the fancier analysis would predict something else.

Not if the coil is located at a current maximum or current minimum point.
How many times do I have to say that before it soaks in?

You've also stated that the current shift through the inductor should
equal the "electrical length" of the antenna "replaced" by the inductor.
In this case, the inductor is "electrically lengthening" the antenna by
either about 45 degrees, or about half that amount, depending on how you
assign the effect of the mounting arrangement.

Nope, it isn't. You antenna is somehow already loaded and is equivalent
to a 50 foot unloaded antenna. Your feedpoint reactance should be around
+j370 for an unloaded antenna so you have about 27 degrees of extraneous
loading somewhere.

So in the past, you've predicted no difference, something like 20 or 45
degrees phase shift, or an indeterminate amount. It's good to see you've
settled on one figure.

There are three possibilities listed earlier. What happens with a coil
depends upon where it is located. Please read that over and over until
it soaks in.

My inductor was placed at the antenna base because I could measure the
currents there with reasonable accuracy.

Yep, you are looking for your keys under the streetlight because the light
is better there than it is where you really lost the keys.

On his web site, Yuri quoted W9UCW as measuring the currents at the ends
of a toroid mounted at the base of the antenna as being 100 mA at the
bottom and 79 at the top. You must, then, believe these measurements to
be in error.

If the toroid is not mounted at a current maximum point, i.e. if the feedpoint
impedance is slightly capacitive, then those figures could be accurate. I
didn't pay any attention to them. Could be his coil causes a larger phase
shift than your coil. You making your antenna too long ensured that
the current maximum point would fall inside the coil. Whether you realize
it or not, you are biasing the outcome of your experiment to agree with your
pre-conceived (sacred cow) notions.

Please note that I am not defending everything Yuri and W9UCW have said so
don't treat that set of three people as a lumped constant. I am not guilty
by association. My postings stand on their own merits or lack thereof.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:
Roy Lewallen wrote:
. . .
So in the past, you've predicted no difference, something like 20 or
45 degrees phase shift, or an indeterminate amount. It's good to see
you've settled on one figure.


There are three possibilities listed earlier. What happens with a coil
depends upon where it is located. Please read that over and over until
it soaks in.

That's the problem. The more times I read what you've posted, the more
confused I've gotten.

My inductor was placed at the antenna base because I could measure the
currents there with reasonable accuracy.


Yep, you are looking for your keys under the streetlight because the light
is better there than it is where you really lost the keys.

You have a unique talent for turning an honest effort at being truthful
and accurate into an insult, as you did with Ian.

On his web site, Yuri quoted W9UCW as measuring the currents at the
ends of a toroid mounted at the base of the antenna as being 100 mA at
the bottom and 79 at the top. You must, then, believe these
measurements to be in error.


If the toroid is not mounted at a current maximum point, i.e. if the
feedpoint
impedance is slightly capacitive, then those figures could be accurate. I
didn't pay any attention to them. Could be his coil causes a larger phase
shift than your coil. You making your antenna too long ensured that
the current maximum point would fall inside the coil. Whether you realize
it or not, you are biasing the outcome of your experiment to agree with
your
pre-conceived (sacred cow) notions.

This is precisely why I've given you the opportunity to choose the
inductor for the 10 MHz test. You choose it so that it will best
illustrate what you say is true. Shucks, I even encourage you to do the
experiments yourself.

. . .

Roy Lewallen, W7EL

Roy Lewallen wrote:
That's the problem. The more times I read what you've posted, the more
confused I've gotten.

Use EZNEC to display the current distribution for a 102 ft center-fed
dipole on 20m. Assume the origin is the feedpoint. Turn the current
phase on. You have 270 degrees of a cosine wave for the current to the
right of the feedpoint. You have a current maximum at zero degrees and
180 degrees. The current magnitude decreases to zero in the first 90
degrees. The current magnitude increases to a maximum negative value
in the second 90 degrees. The current magnitude decreases to zero in
the third 90 degrees. Where one locates a loading coil and how many
degrees it replaces will determine the magnitude and phase of the
current into the coil and the current out of the coil. There are
three possibilities.

You have a unique talent for turning an honest effort at being truthful
and accurate into an insult, as you did with Ian.

Roy, honest efforts are not always valid and the truth sometimes hurts.

This is precisely why I've given you the opportunity to choose the
inductor for the 10 MHz test. You choose it so that it will best
illustrate what you say is true. Shucks, I even encourage you to do the
experiments yourself.

I have some 1.5" diameter, 6 tpi stock. Get a one foot stinger and use
enough of that kind of stock to resonate on 10 MHz. I guarantee the
current will be different into and out of the coil.
--
73, Cecil http://www.qsl.net/w5dxp



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On his web site, Yuri quoted W9UCW as measuring the currents at the ends
of a toroid mounted at the base of the antenna as being 100 mA at the
bottom and 79 at the top. You must, then, believe these measurements to
be in error.

Roy Lewallen, W7EL



Not!
Here what Yuri has on his web site, quote by W9UCW:

"Because of the constant claim that this must be due to the fact that the coil
is so big compared to a wavelength, I measured the in and out current on a
TOROIDAL loading coil used on a 20m mobile antenna. It was a 78" base mast
(including spring and mount) with a 38" top whip (including 12" of alum. tubing
for adjustment).
Below --100ma & Above --79ma
When I moved the coil to the top of the mast and made a horizontal "X" top hat
to resonate it back on the same freq, I got
Below --100ma & Above --47ma

So, It happens even in a totally shielded loading coil with miniscule power
going thru it! Kirchoff has no laws about current being the same on both ends
of inductors. His current law is about one POINT in a circuit and his voltage
law is about a closed loop."

He described exactly how it was done, definitely not at the base.

Yuri

I apologize. I read and was referring to the same quote, and interpreted
it to mean that the first measurement was made with the coil at the base
of the antenna. So where was it -- 78" from the bottom?

Roy Lewallen, W7EL

Yuri Blanarovich wrote:
On his web site, Yuri quoted W9UCW as measuring the currents at the ends
of a toroid mounted at the base of the antenna as being 100 mA at the
bottom and 79 at the top. You must, then, believe these measurements to
be in error.

Roy Lewallen, W7EL




Not!
Here what Yuri has on his web site, quote by W9UCW:

"Because of the constant claim that this must be due to the fact that the coil
is so big compared to a wavelength, I measured the in and out current on a
TOROIDAL loading coil used on a 20m mobile antenna. It was a 78" base mast
(including spring and mount) with a 38" top whip (including 12" of alum. tubing
for adjustment).
Below --100ma & Above --79ma
When I moved the coil to the top of the mast and made a horizontal "X" top hat
to resonate it back on the same freq, I got
Below --100ma & Above --47ma

So, It happens even in a totally shielded loading coil with miniscule power
going thru it! Kirchoff has no laws about current being the same on both ends
of inductors. His current law is about one POINT in a circuit and his voltage
law is about a closed loop."

He described exactly how it was done, definitely not at the base.

Yuri

I apologize. I read and was referring to the same quote, and interpreted
it to mean that the first measurement was made with the coil at the base
of the antenna. So where was it -- 78" from the bottom?

Roy Lewallen, W7EL



Yes,
mast 78" - coil - 38" top whip
we keep saying, looking at typical mobile antenna with loading coil about 2/3
up the quarter wave radiator. The lower the frequency, more loading, more
pronounced effect.

Caution, using toroid current transformers with scope leads would detune the
antenna setup and introduce errors. You can get away with this at the base, but
any stray capacitance up the radiator will detune it and skew the results.
Need to use thermal RF current ammeters or current probe with detector and
small meter together, no wires.

Yuri, K3BU

Thanks for the clarification.

I'm not entirely convinced that the ammeter is the best idea. There are
enough internal wires and coils to introduce a real possibility of error
when in close proximity to an inductor. It shouldn't be as much of a
problem with a toroid, but I'm still a little leery. I agree it would be
difficult to do the measurements well with a scope anywhere but at the
base of the antenna. Current probes and a detecting meter might be ok,
but you'd have to take a lot of care to avoid making an unintentional
loop which would couple to the inductor, and you'd have to calibrate the
potentially nonlinear detector. Phase information would be lacking, too.
I'm waiting for Cecil's response, since by his theory, as I understand
it, we should be able to get a decent phase shift through an inductor at
the base of an antenna providing the antenna is significantly longer
than a quarter wavelength. And if I understand your theory, we should be
able to see a full 30% change in magnitude and 45 degree change in phase
in the current through a base mounted inductor, if it's loading a 45
degree radiatior to resonance. Am I correct? I could measure that with
the same setup but with an antenna removed from the mount. And 30% and
45 degrees should be much easier to resolve with any accuracy than the
2.5 or 5 percent you predict for the setup I did measure.

Incidentally, I take it that your prediction for the setup I did measure
includes an 18 degree phase shift of current from input to output of the
inductor?

Roy Lewallen, W7EL

Yuri Blanarovich wrote:
I apologize. I read and was referring to the same quote, and interpreted
it to mean that the first measurement was made with the coil at the base
of the antenna. So where was it -- 78" from the bottom?

Roy Lewallen, W7EL




Yes,
mast 78" - coil - 38" top whip
we keep saying, looking at typical mobile antenna with loading coil about 2/3
up the quarter wave radiator. The lower the frequency, more loading, more
pronounced effect.

Caution, using toroid current transformers with scope leads would detune the
antenna setup and introduce errors. You can get away with this at the base, but
any stray capacitance up the radiator will detune it and skew the results.
Need to use thermal RF current ammeters or current probe with detector and
small meter together, no wires.

Yuri, K3BU

Incidentally, I take it that your prediction for the setup I did measure
includes an 18 degree phase shift of current from input to output of the
inductor?

Roy Lewallen, W7EL


Yes, I used Cecil estimate/calculation and taking
cos 18 = 0.951056516 which is 4.8943483%

Yuri

Ok. So far, we have your calculation that the output current should be
5% smaller, and 18 degrees shifted in phase (lagging, I presume) from
the input; and Cecil's, that the output current should equal the
current, both in phase and magnitude. I don't know if Richard is going
to do the calculation or not, so I'll wait a little longer. Anyone else
like to hazard a prediction?

Roy Lewallen, W7EL

Yuri Blanarovich wrote:
Incidentally, I take it that your prediction for the setup I did measure
includes an 18 degree phase shift of current from input to output of the
inductor?

Roy Lewallen, W7EL



Yes, I used Cecil estimate/calculation and taking
cos 18 = 0.951056516 which is 4.8943483%

Yuri