Current through coils
 

wrote:
I offered to make a measurement if he would even loosely predict
results and tell us in advance what they would mean. When he didn't
respond, I made the measurements anyway.

Huh? I predicted 14 degrees at 1.9 MHz and 28 degrees at 3.8 MHz
based on Reg's assertion that the coil was self-resonant at 12 MHz.
Once you know the self-resonant frequency, the VF can be calculated.
From there, one can calculate a ballpark delay through the coil.
Your 3 nS measurement seems outside of all possiblity.

This is really simple physics, Tom. If your measurements disagree
with the boundary conditions set by the laws of distributed-
network physics then something is wrong with your measurements.

Let's take a closer look. If the delay through the coil is indeed
3 nS at 4 MHz, the phase shift through the coil at 4 MHz is 4.32
degrees. For a self-resonant phase shift of 90 degrees, the self-
resonant frequency of the coil has to be near (90/4.32)4 MHz =
83 MHz. Now if the self-resonant frequency is really 83 MHz, all
is well, and your measurements agree with distributed network
theory.

But, Tom, don't you think you are insulting our intelligence when
your 100uH coil must have a self-resonant frequency of 83 MHz and
a velocity factor of 0.28 for your measurements to be valid? My
75m bugcatcher coil has a VF of 0.015. Why is your coil 20 times
better than my bugcatcher?

And I have that same coil with 68.5 turns but it is self-resonant
at 57 MHz. How do you explain 2/3 of the number of turns being
self-resonant 25 MHz lower? If you cannot, something is wrong with
your measurements. Don't you care that your 3 nS results are so
outside the bounds of possibility as to be laughable?

Please measure the self-resonant frequency of that coil, Tom.
If it's not 83 MHz, your measurements are bogus. I suggest the
self-resonant frequency is actually lower than the 12 MHz
predicted by Reg.

Incidentally, the IEEE would surely be interested in your ability
to violate the distributed-network laws of physics. Maybe you
can talk them into replacing that body of physics with your pet
lumped-circuit model. Good luck on that one.

3 nS delay through a 100 uH coil???? That would be funny if it
was April First. That's why I requested that you describe your
test setup which you refused to do.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Richard Clark wrote:

Cecil Moore wrote:
I was as naive as Galileo in front of the court run by religious priests.

Has Cecileo been dropping his balls off of the Tower of Pisa again?

:-) I dropped them off the wrong side and rewrote the law of gravity.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

All explainations of the time delay I measured and why it happens are
on my website.

http://www.w8ji.com/inductor_current_time_delay.htm

and

http://www.w8ji.com/mobile_and_loaded_antenna.htm

and associated links.

The self-resonant frequency of the inductor is shown by a large rise in
time delay. Cecil is now trying to rewrite the self-resonant frequency
of the inductor I tested by using his own seriously flawed theories,
but despite the fact it appears to be clearly shown in the network
analyzer data at about 16 MHz.

http://www.w8ji.com/images/Inductor/...time-delay.jpg

Cecil's normal tactic is to change what other people say. To read a
history of the very same behavior with someone else please read:

http://www.w8ji.com/RRAA_post.htm


73 Tom

Current through coils
 

Richard Clark wrote:

Analog designers, fully expecting a continuum of results spanning from
classic to truly exaggerated, can cope with this. For digital
designers, this is a clear example of confounding expectations of a
binary result.

73's
Richard Clark, KB7QHC

I've worked with a few digital designers. Many of them expect a unary
result.

tom
K0TAR

Current through coils
 

wrote:
The self-resonant frequency of the inductor is shown by a large rise in
time delay. Cecil is now trying to rewrite the self-resonant frequency
of the inductor I tested by using his own seriously flawed theories,
but despite the fact it appears to be clearly shown in the network
analyzer data at about 16 MHz.

Well then, if 10" is 1/4WL at 16 MHz, its velocity factor is 0.054.
10" on 4 MHz with a VF of 0.054 is 0.063WL or 22.6 degrees. Why
didn't you measure 22.6 degrees or 15.7 nS of delay?

You measured 3 nS or 4.32 degrees of delay. Something is obviously
wrong. The VF couldn't change by a factor of 5 to 1 going from 16
MHz to 4 Mhz.

I think I know what happened. You forgot and left the test wire
attached in parallel with the test coil. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Tom Donaly wrote:
Cecil, have you ever read the book _Don Quixote_, by Cervantes?
There's a character in there you remind me of.

Tom, please don't tell me that you also believe that a distributed-
network analysis using wave reflection theory is "gobbledygook".
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Cecil Moore wrote:

wrote:
The self-resonant frequency of the inductor is shown by a large rise in
time delay. Cecil is now trying to rewrite the self-resonant frequency
of the inductor I tested by using his own seriously flawed theories,
but despite the fact it appears to be clearly shown in the network
analyzer data at about 16 MHz.

In case my previous reply was confusing to some people let's
do it with a piece of transmission line.

We have a piece of transmission line that we measure to be
1/4 wavelength on 16 MHz. That's easily done with an MFJ-
259B. We hand it over to Tom who takes it and measures a
3 nS delay through it at 4 MHz. What's wrong with this
picture?
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

wrote:
(snip)
Time delay measurements of current at each terminal of a "bug-catcher
style" loading coil are now at:
http://www.w8ji.com/inductor_current_time_delay.htm

Thank you for posting the test results. But I see no information that
would allow me to reproduce it. What test equipment and what
measurement set-up was used to produce these results?

Current through coils
 

wrote:
Cecil's normal tactic is to change what other people say.

I could never bring myself to cut and paste and mix and match
numerous postings over many hours to try to twist what someone
has said, like you did with my postings. I could ask, Tom are
you a criminal?, and wait for the next time you posted a yes
to some other question. Cut and paste those two things together
and I would be using W8JI's arguing technique. But you know
what you are, Tom, without me having to point it out.

To read a
history of the very same behavior with someone else please read:

http://www.w8ji.com/RRAA_post.htm

That is really funny, Tom. You are defending the lumped-constant
model, known to fail in a standing wave environment, by measuring
standing wave current? You are really something else.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

On Sun, 12 Mar 2006 02:29:51 GMT, Cecil Moore wrote:

Tom Donaly wrote:
Cecil, have you ever read the book _Don Quixote_, by Cervantes?
There's a character in there you remind me of.

Tom, please don't tell me that you also believe that a distributed-
network analysis using wave reflection theory is "gobbledygook".

Hmm, Tom, let me guess - Dulcinea. The object of Quixote's attention
who never appears, but is always dreamt about.

Current through coils
 

John Popelish wrote:
wrote:
(snip)
Time delay measurements of current at each terminal of a "bug-catcher
style" loading coil are now at:
http://www.w8ji.com/inductor_current_time_delay.htm

Thank you for posting the test results. But I see no information that
would allow me to reproduce it. What test equipment and what
measurement set-up was used to produce these results?

I used a HP8753C network analyzer with small current transformers
similar to those used in directional couplers.

I calibrated using normal proceedures, and verified calibration by
inserting known transmission lines. For example when I substituted a
very short jumper, time delay was a few picoseconds. When I connected a
10 foot RG-8X jumper, time delay was about 13.5 nS.

For my phase angle measurements I used a dual channel HP vector
voltmeter with a HP generator, and similar current transformers when
measuring current.

I suppose most people would want to use a scope, but it would not be
near the accuracy of a dual channel vector voltmeter or especially a
vector network analyzer.

I have regular test fixture built on blank PC boards, since I do this
stuff every week for work. It does not "fit" a large coil well, so I
had to support the coil on two tall blocks of styrofoam and clip lead
to it.

I do have a large fixture that is a four foot PC board "box" with
various test jacks for connections to probes I use with larger
components, but my bench is to cluttered to fit it right now. In any
event a groundplane several inches away doesn't seem to bother things.
The only thing that moved when I moved the inductor close to the
fixture was the self-resonant frequency came down a few MHz. Time
delays did not change much unless I added an extra foot of clip lead,
then they increased about 1nS.

If it's useful, I guess I could add some more stuff. But probably
nothing extensive until after Dayton.

Since all of my data agrees with data made a few years ago by a
different person using a different method with different equipment, and
since it agrees with reference material I have, I don't see any reason
to treat it like cutting edge results. The physics is pretty solid, and
the measurements agree.

73 Tom

Current through coils
 

wrote:
When I connected a
10 foot RG-8X jumper, time delay was about 13.5 nS.

Let's take a look at the measurement results. That
13.5 nS delay through the coax would make that piece
of RG-8X 1/4WL self-resonant at ~18.5 MHz, higher than
the specified 16 MHz self-resonant frequency for the
coil. So the laws of physics would dictate that the
delay through the coil cannot be less than the delay
through that piece of coax.

By definition, the physical meaning of that piece of
coax being 1/4WL self-resonant at 18.5 MHz is that
it takes 1/2 of a cycle in time for the forward wave
to make a round trip to the end of the coax and back.
1/2WL of a cycle at 18.5 MHz is 27 nS. So the one-
way delay through the coax is 1/2 of 27 or 13.5 nS.

By definition, the physical meaning of that 10" coil
being 1/4WL self-resonant at 16 MHz is that it takes
1/2 of a cycle in time for the forward wave to make
a round trip to the end of the coil and back. 1/2
of a cycle at 16 MHz is 31 nS. So the one-way
delay through that coil is 1/2 of 31 or 16.5 nS.

The 1/4WL self-resonance point *IS* a measure of the
delay through the coil just as it is a measure of
the delay through a piece of transmission line.

If the coil is indeed 1/4WL self-resonant at 16
MHz, the one-way delay through the coil is *already
known* to be 16.5 nS and that is what should have
been measured. The fact that the *known value* of
the delay through the coil was not measured runs up
a red flag and is technical proof that something was
amiss with the reported results.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Current through coils
 

John Popelish wrote:
Thanks much. This helps me to visualize your method in a much more
complete way. I think a photo of the test apparatus would make a fine
addition to your web page documenting this result. I am especially
interested on how all this stuff was arrayed in space during the test.

John, would you agree or disagree with me that for
a well-designed coil, the delay through the coil is
fixed by the laws of physics as 1/4WL on the self-
resonant frequency?

If the self-resonant frequency of a well-designed coil
is measured at 16 MHz, then the delay through the coil
is 90 degrees at 16 MHz and therefore equal to 15.625 nS.

Using the self-resonant frequency to determine the
delay is an easy and accurate way to measure that
delay.

If the delay through the coil, measured at 1/4 the
self-resonant frequency, is appreciably different
from the 15.6 nS measured at 16m, then the measurement
contains an error.

Agree/disagree?
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

wrote:
Since all of my data agrees with data made a few years ago by a
different person using a different method with different equipment, and
since it agrees with reference material I have, I don't see any reason
to treat it like cutting edge results.

You've probably hit the nail right on the head there,
Tom. If your results agree with Roy's then you were
again more than likely measuring standing-wave current
and therefore gained nothing by making those measurements.

How do you explain a well-designed coil exhibiting a
measured delay of 15.6 nS at 16 MHz and a measured
delay of 3 nS at 4 MHz? Don't you realize that is an
impossibility according to the laws of physics? If
the coil is well-designed at 16 MHz, it would also
be well-designed at 4 MHz and exhibit very close
to the same delay at both of those frequencies.
Do you really think the delay changed by 81% between
those two frequencies?

Build yourself an SWR meter calibrated for the Z0
of that coil. Measure the SWR in your coil circuit.
I'll bet it will be nearly infinite. Seems you are
guilty of presupposing the proof again.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Cecil Moore wrote:
John Popelish wrote:

Thanks much. This helps me to visualize your method in a much more
complete way. I think a photo of the test apparatus would make a fine
addition to your web page documenting this result. I am especially
interested on how all this stuff was arrayed in space during the test.


John, would you agree or disagree with me that for
a well-designed coil, the delay through the coil is
fixed by the laws of physics as 1/4WL on the self-
resonant frequency?

I haven't formed a strong opinion either way, yet. I am not an
inductor expert, but am learning lots of interesting things, here. I
know that filters with sharp resonances (i.e. multiple db ripple
chebychev) often have a delay that varies dramatically over rather
narrow frequency ranges near cut off.

But I am finding the discussion and test results fascinating. I don't
care who has what opinion. I am just interested in what is factual,
and sometimes that can be tricky to determine and understand in a more
general context. That is why I am interested in the details of the
measurement method as much as I am in the result. I am still having a
bit of trouble visualizing how the coil was instrumented and
terminated to get this result. I am also a beginner when it comes to
S parameters.

My reservation with you and few others is your emotional investment in
being correct. It makes your opinions less trustworthy. I get the
feeling that some of you care more about having had the right answer
than what the result tells us about reality.

I have been wrong lots of times, and I got over it (sometimes with
difficulty). I accept that I will be wrong about lots more things
before I die. The best I can hope for is to realize my mistakes as
rapidly and gracefully as possible.

If the self-resonant frequency of a well-designed coil
is measured at 16 MHz, then the delay through the coil
is 90 degrees at 16 MHz and therefore equal to 15.625 nS.

Using the self-resonant frequency to determine the
delay is an easy and accurate way to measure that
delay.

For a pure delay process, like a classical transmission line, or
acoustic delay line, I agree. I am not so sure for something with
more ways energy communicates across it, like an extended inductor.

That is the open question, in my mind.

If the delay through the coil, measured at 1/4 the
self-resonant frequency, is appreciably different
from the 15.6 nS measured at 16m, then the measurement
contains an error.

Agree/disagree?

No. Not yet. When the test method has been agreed upon, and exactly
what that method measures is understood by all interested parties,
there will be no need for such opinions. The results will be the
results. Then we can work on our opinions of what the results mean in
a more general context (how we extrapolate to other, related, but
different cases.

Current through coils
 

John Popelish wrote:
I am still having a
bit of trouble visualizing how the coil was instrumented and terminated
to get this result. I am also a beginner when it comes to S parameters.

I think Tom did what I did the other night. I hooked the coil
across my IC-756PRO's output, used minimum power, and tried
to supply 4 MHz power to the 4+j1250 ohm coil that I have.
It naturally rejected (reflected) virtually all of that power.
I found, as Tom did, that the standing wave current at both
ends has virtually identical phases but that is already known.
The delay through the coil simply cannot be tested in that
test arrangement. Tom just repeated Roy's experiment of a
few years ago and obtained the same meaningless results.
So did I so I didn't even bother to report them.

My reservation with you and few others is your emotional
investment in being correct. It makes your opinions less
trustworthy.

Whoa there, I just made a mental blunder about radiation
resistance and readily admitted it. My emotional investment
is in fighting falsehoods, myths, and old wives' tales.
That's all.

The test method for determining the delay through a piece
of transmission line or a coil is the same as it has been
for more than a century. Find the 1/4WL self-resonant
point and calculate the delay. Other methods, resulting
in far different results, are obviously invalid.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Cecil Moore wrote:
John Popelish wrote:

I am still having a bit of trouble visualizing how the coil was
instrumented and terminated to get this result. I am also a beginner
when it comes to S parameters.


I think Tom did what I did the other night. I hooked the coil
across my IC-756PRO's output, used minimum power, and tried
to supply 4 MHz power to the 4+j1250 ohm coil that I have.
It naturally rejected (reflected) virtually all of that power.
I found, as Tom did, that the standing wave current at both
ends has virtually identical phases but that is already known.
The delay through the coil simply cannot be tested in that
test arrangement. Tom just repeated Roy's experiment of a
few years ago and obtained the same meaningless results.
So did I so I didn't even bother to report them.

My reservation with you and few others is your emotional
investment in being correct. It makes your opinions less
trustworthy.

Whoa there, I just made a mental blunder about radiation
resistance and readily admitted it. My emotional investment
is in fighting falsehoods, myths, and old wives' tales.
That's all.

But the goal of such "fights" should be altering other's opinions.
How's that been working out for you? ;-)

The test method for determining the delay through a piece
of transmission line or a coil is the same as it has been
for more than a century.

Have you got a reference to a Bureau of Standards bulletin on this
method to measure inductive current delay? It doesn't work for
filters made of lumped inductors, capacitors and resistors.
Otherwise, there would not be special designs that sacrifice other
properties, to keep delay almost constant as frequency changes.

Wait a second, an inductor at resonance is a filter made of
inductance, capacitance and resistance (and transmission line
effects). Hmm.

Find the 1/4WL self-resonant
point and calculate the delay. Other methods, resulting
in far different results, are obviously invalid.

"Obvious" must be something in the eye of the beholder.

If a 2 port device (Are there really any perfect 2 port devices that
don't have an implied 3rd port?) involves only a single energy
transport mechanism from one port to the other, this is a bit closer
to obvious. But if the device uses competing, parallel energy
transport mechanisms (EM waves, inter turn capacitance, mutual
inductance, etc.) it is less clear that the combination of energy
transport effects has a constant delay effect on a current wave as
frequency changes.

Current through coils
 

John Popelish wrote:
But the goal of such "fights" should be altering other's opinions. How's
that been working out for you? ;-)

That's not my goal at all, John. My goal is to discuss the
technical facts. I really don't care if anyone "alters
their opinions" or not. That has been a personality
characteristic since my early days. My sister just
remarked on that same fact a few days ago. She said,
"You have never cared what other people think about
you." It wasn't a criticism, just an observation.

We may understand the results of Tom's latest
measurement by considering the following:

50 ohm source===1 WL 50 ohm lossless coax===8+j2500 load

Since the transmission line is lossless, this doesn't
change anything except for the additional one cycle delay
through the line.

What's the system SWR? I get 16000:1. I asked Tom
to measure the currents in the absence of a high SWR
and he takes his measurements in a 16000:1 SWR
environment. How well do you think he honored my
request for an SWR of 1:1? Shucks, he only missed
it by 1,600,000%. :-)

There is essentially no net energy flow in the above
network. Why are we suprised to measure equal standing
wave currents on each side of the coil? It wouldn't have
surprised me if Tom had measured *zero* phase shift just
like the lumped-circuit model predicts. The traveling-
wave delay through a coil simply cannot be measured
using Tom's methods.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Richard Clark wrote:
On Sun, 12 Mar 2006 02:29:51 GMT, Cecil Moore wrote:


Tom Donaly wrote:

Cecil, have you ever read the book _Don Quixote_, by Cervantes?
There's a character in there you remind me of.

Tom, please don't tell me that you also believe that a distributed-
network analysis using wave reflection theory is "gobbledygook".


Hmm, Tom, let me guess - Dulcinea. The object of Quixote's attention
who never appears, but is always dreamt about.

Hi Richard,
that sounds like Cecil's theory, which he's always ready to
defend with his strong right arm. I can't believe all the fuss he's made
over something as trivial as a loading coil.
73,
Tom Donaly, KA6RUH

Current through coils
 

Cecil Moore wrote:

Tom Donaly wrote:

Cecil, have you ever read the book _Don Quixote_, by Cervantes?
There's a character in there you remind me of.


Tom, please don't tell me that you also believe that a distributed-
network analysis using wave reflection theory is "gobbledygook".

It is when the components are small enough in relation to a wavelength
that you don't have to use "a distributed-network analysis". Actually,
the way you've been talking about it, lately, it sounds more like
word salad than gobbledygook.
73,
Tom Donaly, KA6RUH

Current through coils
 

Cecil Moore wrote:
(snip)
We may understand the results of Tom's latest
measurement by considering the following:

50 ohm source===1 WL 50 ohm lossless coax===8+j2500 load
(snip)

I am not sure I understand this. As I understand an S parameter
tester, both source and load are 50 ohms. Tom says he fed and
monitored the signal with a pair of current transformers. I assume
that one transformer was fed from the 50 ohm source, and the other fed
the 50 ohm load, and S21 is the forward transfer gain parameter that
the analyzer can use to calculate a net delay at any frequency. But
if I am right about these connections, it leaves open the question of
what was on the other side of the current transformers, if the coil
was between them. Were those points grounded, terminated, what?

Current through coils
 

Tom Donaly wrote:
that sounds like Cecil's theory, which he's always ready to
defend with his strong right arm. I can't believe all the fuss he's made
over something as trivial as a loading coil.

As long as someone asserts that there is no phase shift
through a 75m mobile bugcatcher coil, I will continue
pointing out that they are wrong. The phase shift
through a 75m bugcatcher coil is approximately the
same as it is at the bugcatcher coil's self-resonant
frequency. That's simply a law of physics that some
people wish didn't exist but it does in spite of
their wishes.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

John Popelish wrote:

Cecil Moore wrote:
We may understand the results of Tom's latest
measurement by considering the following:

50 ohm source===1 WL 50 ohm lossless coax===8+j2500 load

I am not sure I understand this. As I understand an S parameter tester,
both source and load are 50 ohms. Tom says he fed and monitored the
signal with a pair of current transformers.

I don't think he fed the coil with a current transformer.
I think he simply had the coil across the signal generator's
output terminals with current pickup devices at each end
of the coil. The above diagram doesn't change anything
about his configuration but does point out the conceptual
mistake he made which is the identical conceptual mistake
that he and Roy have been making for years. Their model
presupposes their measured results. How could their
results be anything else?
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

http://www.w8ji.com/mobile_and_loaded_antenna.htm

http://www.w8ji.com/inductor_current_time_delay.htm

Current through coils
 

On Fri, 10 Mar 2006 03:12:11 GMT, "Jerry Martes"
wrote:

I have a HP8405A Vector Voltmeter I'll give you and even pay the shipping
if that is of any help with the measurements.

Hi Jerry,

So, any taker?

73's
Richard, KB7QHC

Current through coils
 

"Richard Clark" wrote in message
...
On Fri, 10 Mar 2006 03:12:11 GMT, "Jerry Martes"
wrote:

I have a HP8405A Vector Voltmeter I'll give you and even pay the
shipping
if that is of any help with the measurements.

Hi Jerry,

So, any taker?

73's
Richard, KB7QHC

Hi Richard

No takers. No replies.

Jerry

Current through coils
 

wrote:
http://www.w8ji.com/inductor_current_time_delay.htm

Don't you think it only fair to to the readers to
indicate on that new web page that you measured
the current in the midst of of a 16000:1 SWR?
That's what I get for 8+j2500 being fed by a
50 ohm source.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Jerry Martes wrote:
No takers. No replies.

Jerry

Jerry, I've sent you two emails. Did you not get them?
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

"Cecil Moore" wrote in message
. com...
Jerry Martes wrote:
No takers. No replies.

Jerry

Jerry, I've sent you two emails. Did you not get them?
--
73, Cecil http://www.qsl.net/w5dxp

No Cecil, I didnt. Maybe I wrote my address wrong.

I figured you realized that the HP Vector Voltmeter wasnt capable of
providing the data needed for this discussion.

Jerry KD6JDJ

Current through coils
 

Jerry Martes wrote:
"I figured you realized that the HP Vector Voltmeter wasn`t capable of
providing the data needed for this discussion."

More likely necessary. It is dead simple.

You have a whip with a loading coil somewhere in the circuit under it.
The r-f energy is reflected by the open circuit at the tip of the
antenna. It must return toward the sender. There is no place else to go.

Anything feeding the antenna is in the path. Volts and amps at any and
all points along the way are acted upon by the incident and the
peflected waves. Straight wire or coil, the effect is the same as there
is a periodic variation in volts and amps due to the combination of the
effects of volts and amps from both directions.

Should the current at both terminals of a loading coil happen to be the
same, it would likely be a rare coincidence.

Best regards, Richard Harrison, KB5WZI

Current through coils
 

Jerry Martes wrote:
No Cecil, I didnt. Maybe I wrote my address wrong.

I think the Reply All feature on my newsreader must not be
working. I didn't get any notice that it didn't go through.
I'll send you a regular email.

I figured you realized that the HP Vector Voltmeter wasnt capable of
providing the data needed for this discussion.

Here's the procedure for measuring the electrical length of
a base loading coil. That's the same as the delay through
the coil.

1. Mount your base loading coil on your vehicle and remove
the stinger. Note that the current is zero at the top of
the coil with the stinger removed.

2. Use an antenna analyzer, like an MFJ-259B to locate the
self-resonant frequency. It will be the first frequency
going up in frequency for which the reactance is zero and
the resistance is very low. My 75m bugcatcher coil has
a self-resonant frequency of 6.6 Mhz which is an
electrical 90 degrees at 6.6 MHz.

3. Calculate the length of the RF cycle at the self-resonant
frequency. 1/6600000 = 152 nS for 360 degrees at 6.6 MHz.
The coil is an electrical 90 degrees long on its self-resonant
frequency so the delay through the coil is 152/4 = 38 nS.

38 nS is also the approximate delay through the coil when
used as a base loading coil on 4 MHz. One RF cycle on 4 MHz
takes 250 nS so 90 degrees (1/4WL) of that cycle is 62.5 nS.
The coil is providing 38/62.5 = 61% of the antenna on 4 MHz.

Forget the bogus coil delays posted by the "experts". They
are measuring standing wave current which is known not to
change phase on either end of the coil and it doesn't do a
bit of good to measure something that doesn't ever change.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Richard Harrison wrote:
Should the current at both terminals of a loading coil happen to be the
same, it would likely be a rare coincidence.

All one has to do to see radical changes in the currents
at the ends of the coil is move the coil up and down
a 3/4WL radiator. One can find a place where current
at the top of the coil is five times the current at
the bottom of the coil. That's just the way standing
wave current works. Too bad there are so many myths
and old wives' tales being spread about it by alleged
"experts" who have forgotten EE201.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

On Mon, 13 Mar 2006 03:41:34 GMT, Cecil Moore wrote:
I'll send you a regular email.
....
Use an antenna analyzer, like an MFJ-259B to locate the
self-resonant frequency.

Vector VOLTmeter?
VECtor Voltmeter?!!!

I don' need no stinkin' VECtor VOLTmeter!

Hi Jerry,

Can you take another dumpster dive and see if you can find a Raster
Ammeter?

73's
Richard Clark, KB7QHC

Current through coils
 

"Richard Clark" wrote in message
...
On Mon, 13 Mar 2006 03:41:34 GMT, Cecil Moore wrote:
I'll send you a regular email.
...
Use an antenna analyzer, like an MFJ-259B to locate the
self-resonant frequency.

Vector VOLTmeter?
VECtor Voltmeter?!!!

I don' need no stinkin' VECtor VOLTmeter!

Hi Jerry,

Can you take another dumpster dive and see if you can find a Raster
Ammeter?

73's
Richard Clark, KB7QHC

Hi Richard

There are sooo many things I dont know anything about. Raster Ammeter is
one of the many things I havent even heard about.
I sure would like to learn how to use a Vector Voltmeter.
Right now, I cant measure impedance (with any confidance of accuracy) when
their VSWR is below about 1.5 to 1 on a 50 ohm line at 137 MHz.

Jerry

Current through coils
 

On Mon, 13 Mar 2006 06:39:03 GMT, "Jerry Martes"
wrote:

Raster Ammeter is one of the many things I havent even heard about.

"It's a joke, son."
Foghorn Leghorn

Current through coils
 

"Richard Clark" wrote in message
...
On Mon, 13 Mar 2006 06:39:03 GMT, "Jerry Martes"
wrote:

Raster Ammeter is one of the many things I havent even heard about.

"It's a joke, son."
Foghorn Leghorn

Hi Richard

The "raster" had all the earmarks of an imaginary device. I sensed it
was a put on. The problem I have is my inexperience requires that I dont
assume *anything*.
I feel like Rip Van Winkle. The engineering community has developed a
whole lot of nice things since I left it in 1969. And, its like I've
been sleeping for 37 years.

Jerry

Current through coils
 

On Mon, 13 Mar 2006 06:39:03 GMT, "Jerry Martes"
wrote:
[snip]

There are sooo many things I dont know anything about. Raster Ammeter is
one of the many things I havent even heard about.

Reminds me of my youth. I worked in an automotive parts store back
when you actually had to know something about cars and how to read a
paper catalog. We'd test the new guys by asking them to find a
radiator cap for a Corvair, a set of spark plugs for a Cummins, an oil
pan gasket for a Powerglide transmission....


I sure would like to learn how to use a Vector Voltmeter.
Right now, I cant measure impedance (with any confidance of accuracy) when
their VSWR is below about 1.5 to 1 on a 50 ohm line at 137 MHz.

Have you looked at this?

http://www.k6mhe.com/n7ws/AN77-3.pdf

Current through coils
 

Richard Clark wrote:

Cecil Moore wrote:
Use an antenna analyzer, like an MFJ-259B to locate the
self-resonant frequency.

Vector VOLTmeter?
VECtor Voltmeter?!!!

I don' need no stinkin' VECtor VOLTmeter!

Actually, unlike Tom (who rushes in where angels fear to
tread) I cannot figure out how to use the VVM to make
a valid measurement of what we are trying to measure. If
I cannot figure that out, then the VVM won't do me any
good as Tom's setup didn't do him any good and just
confused him all over again by tricking him into making
his measurement in an SWR = 16000:1 environment. I'm
truly surprised his standing-wave current delay
measurement wasn't zero.

Guess everyone sees the danger in trying to guess what
the results of someone else's measurement will be. Tom
should have measured something around 15.6 degrees. The
fact he didn't sends up a very large red flag.

Another problem is that the delay through the coil
changes drastically between bench isolation and being
installed directly above a GMC pickup's ground plane
because of the enormous increase in coil capacitance
to that ground plane. So the delay through the coil
needs to be measured in the physical environment in
which it is operated. It is virtually impossible to
eliminate reflections from a 75m mobile bugcatcher
system so the VVM can't measure what we are trying
to measure.

The question is: For a well-designed coil, is the self-
resonance method valid for determining the delay through
a coil at HF frequencies below the self-resonant frequency?
Since that's been an accepted way of doing it for more
than a century, I don't see how anyone could object.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Jerry Martes wrote:
I feel like Rip Van Winkle. The engineering community has developed a
whole lot of nice things since I left it in 1969. And, its like I've
been sleeping for 37 years.

Ever heard of a "Triactuated Multicomplicator"?
--
73, Cecil http://www.qsl.net/w5dxp