Roy Lewallen wrote:
Now, that's quite an insult, based on a total lack of information about
my career and what I've accomplished.

I freely admit that there was absolutely no truth or validity to the insult.
It was a less than subtle response to your subtle put-downs of some engineers
whose thoughts, style, and results differs from yours. An appropriate response
was difficult to gage. I'm not very subtle and I apologize if the magnitude of
my response was unjustified.

To all readers of this newsgroup:
I have been an admirer and supporter of Roy's contributions to amateur
radio for decades and I will continue to be. This is a public apology.
Roy doesn't really remind me of that engineer who used to work for me.
--
73, Cecil http://www.qsl.net/w5dxp



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To all readers of this newsgroup:
I have been an admirer and supporter of Roy's contributions to amateur
radio for decades and I will continue to be. This is a public apology.
Roy doesn't really remind me of that engineer who used to work for me.
--
73, Cecil http://www.qsl.net/w5dxp



Same here, ditto!

Just that one would expect from a person like that to be more open minded and
less infected by W8JI/G4FGQ (ridiculing absolute knowitalls) virus. We live,
learn and still die stupid (who said that? :-)

Yuri

Cecil, W5DXP wrote:
"---isn`t everything moot after Kraus tells us that the antenna coil can
cause a 180 degree phase reversal?"

Yes. The Kraus example is a resonant circuit of a coil which with its
inherent self capacitance which can produce a leading or lagging total
impedance, depending on frequency.

B. Whitfield Griffith, Jr. demonstrates this with a series LRC circuit
on page 108 of "Radio-Electronic Transmission Fundamentals".

Total impedance, Zt = R+jomegaL-J/omegaC.

Griffith tabulates ZL, ZC, and Zt for 2.4, 2.5, 2.6, 2.7, and 2.8 MHz.
R=30 ohms at all frequencies.

2.4 MHz, j226ZL, -265ZC, 30-j39Zt
2.5 MHz, j236ZL, -j255ZC, 30-j19Zt
2.6 MHz, j245ZL, -j245ZC, 30-j0Zt
2.7 MHz, j254ZL, -j236ZC, 30+j18Zt
2.8 MHz, j264ZL, -j227ZC, 30+j37Zt

Griffith also gives Zt in polar coordinates but I don`t need to copy
that to show that reactance can be either positive or negative in a
circuit with both inductance and capacitance.

Best regards, Richard Harrison, KB5WZI

"Roy Lewallen" wrote in message
...

Are you going to insist that it be one of these ferrite core jobs, or is
it
more like ones on a HF6V?

Is there something about a "ferrite job" that makes it follow different
rules? But the answer is no to both. I insist on using a physically
small toroid wound on a powdered iron core. Only after people understand
how a physically small inductor works will they have any chance of
understanding how a physically long one does.

The discussion is about 'long' inductors. You continue to try to steer the
discussion away from them. Why is that?

73, Jim AC6XG

"Cecil Moore" wrote in message
...
Reg Edwards wrote:
A design which 'exceeds' specified performance is as poor as one which
'under exceeds'.

It would have cost money and space to add the circuits to bring the
measurable jitter up to the RS232 specification allowable threshold.
You really think I should have done that?

Designs which overachieve are an embarrassment to the proletariat, and are
to be discouraged.

73, ac6xg

Yuri Blanarovich wrote:
We live, learn and still die stupid (who said that? :-)

Einstein, in so many words.
--
73, Cecil http://www.qsl.net/w5dxp

"One thing I have learned in a long life: that all our science, measured
against reality, is primitive and childlike ..." Albert Einstein



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Roy Lewallen wrote:
For anyone who cares, the magnitude of the current out of the inductor
in the later test measured 5.4% less than the current in.

That would be one amp in and 0.9460 amps out. The angle whose cosine
is 1 is zero deg. The angle whose cosine is 0.9460 is 18.9 degrees.
So Yuri's estimate of an 18 degree effect was pretty accurate.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote in message ...
Ok,

For anyone who cares, the magnitude of the current out of the inductor
in the later test measured 5.4% less than the current in. No phase shift
was discernible. An analytical person could build on this information to
investigate the properties of longer inductors placed elsewhere in the
antenna.

Thank you for the comments, Cecil, Yuri, Richards, Art, and others. I've
learned a good lesson from this -- that this isn't an appropriate forum
or appropriate audience for the sort of quantitative analysis and
reasoning I'm familiar and comfortable with. And that the considerable
time and effort required to make careful measurements is really of very
little benefit -- certainly not anywhere near enough to justify it.

Interesting though. I think I may try to rig up some couplers so I can
do this myself. I have the dual channel scope, but I need to build the
couplers.

With a great sigh of relief from everyone, I'm sure, I'll now turn this
thread back over to Yuri, Cecil, et al.

My apologies to everyone for taking up so much bandwidth.

None needed. If the group can have multiple postings on amateur
racists, and other assorted problem children, then I see no problem
with this thread, no matter how long it gets. So far, your tests,
while not being a bugcatcher type coil seem to match my expectations
fairly closely. I never expected to see no reduction at all. In my
view, even a large 75m bugcatcher coil is still a lumped coil, and
will pretty much act as one. Why do I think this? Because the overall
form is still very small per wavelength. IE: 90 degrees is appx 65 ft.
So far no one has argued that the current taper UNDER the coil is
suspect when modeled. Most all seem to agree that the current
distribution is dramatically improved when the coil is raised up the
mast. If you model a 10 ft whip, using a center load coil, the model
will show max current at the coil. Here is an example using eznec....

EZNEC Demo ver. 3.0

Vertical over real ground 11/12/03 11:30:20 AM

--------------- CURRENT DATA ---------------

Frequency = 3.85 MHz.

Wire No. 1:
Segment Conn Magnitude (A.) Phase (Deg.)
1 Ground 1 0.00
2 1.0013 -0.01
3 1.0036 -0.02
4 1.0072 -0.03
5 1.0122 -0.04
6 1.0192 -0.04
7 1.029 -0.05
8 1.0432 -0.06
9 1.0691 -0.06
10 1.1036 -0.07 ......coil is at segment 10
11 .98384 -0.07
12 .87242 -0.07
13 .77233 -0.07
14 .67604 -0.07
15 .58163 -0.07
16 .48789 -0.08
17 .3938 -0.08
18 .2982 -0.08
19 .19932 -0.08
20 Open .08787 -0.08

OK. Lets say the coil in the real world is one foot long. That is appx
1/10 of the total antenna length. Will there be any argument that max
current will occur at the coil? I hope not...
OK. Lets say that Yuri, et el, are correct and there is a noticable
taper of current across the coil from bottom to top. I still think
they are being fooled by the capacitance above the coil, which is
where they are testing, but thats another issue.
Say you have a 1 ft section of the antenna, "coil" and it is found
that there is a noticable current taper across it. What would this
amount to in the real world? To me, nothing much at all. I don't think
it would have any effect on the way I build mobile antennas. It won't
have any effect on where I mount my coil, because I am already using
the best locations possible. These "best" coil locations are old news
and easily calculated using a program such as Reg's "vertload" or even
info in the ARRL antenna handbook.
Would this current taper in a 1/10 section of the antenna drastically
skew any modeling done of this antenna? It's possible, but again, I
really doubt it.
BTW, I think I said earlier that the modeling of these mobile whips
didn't do a good job of showing increases in performance due to
changes in coil position.
But that seems to not be the case. I may have been thinking of
something else. I do show increases in gain when the coil is raised
from a base load, to a center load. As far as the reflected currents,
and phase, etc, I just don't see that causing a major difference in
the current across the coil. Some difference I'm sure, but I don't
think it would be enough to cause a difference in either the
calculation of best coil location, or in the modeling of the antenna.
I'm still of the opinion that if you measure the current at the top of
the coil, where it is attached to the capacitance section, this will
slightly stunt the upper coil measurement. The eznec plot *seems* to
agree. I'm still of the opinion that the current is *fairly* constant
across the coil, but I'm not losing any sleep over it. I'll still be
building my antennas the same way I have been. Nothing will change,
even if it's determined they are correct about this current taper
across the coil. MK

"Roy Lewallen" wrote in message
...
Do we agree that the amount of differential will depend on the number of
'degrees missing' from the length of the antenna?

No. In a few minutes, I'll post a description of a more recent
measurement I made that refutes this. Of course, elementary circuit
theory refutes it also, which is the basis for my disagreement.

Perhaps the statement was poorly worded. The presumption is that the
"missing degrees" of length are supplied by the coil. Do you believe this
is untrue? Realize of course, that a sufficiently simple model can fail to
describe any phenomenon which has been oversimplified in the model.

Do we agree that the position of the loading coil plays a significant.
role in determining how much of a current differential will appear
across
it?

If you're talking about a physically long coil, yes. If you're talking
about a physically small coil, no.

Yes, Roy. The discussion is limited to those coils which cause a current
differential from one end to the other. The other kind don't meet the
requirement. :-)

But if you believe that the amount of antenna the coil "replaces"
determines the differential, wouldn't this be true regardless of the
placement of the coil in the antenna?

No. Note the shape of the current vs position curve along the antenna. It
doesn't change linearly with position. There are relatively flat regions
near the ends, and there's region nearer the middle where the current
changes rapidly with position. Presumably it's related to the way the
impedance changes with position along the antenna.

Are you going to insist that it be one of these ferrite core jobs, or is
it
more like ones on a HF6V?

Is there something about a "ferrite job" that makes it follow different
rules?

The 'ferrite jobs' provide considerably more inductance for a given coil
size. Fewer turns, shorter length of wire, physically smaller, no
radiation. Do you agree there's a difference between air and ferrite?

Only after people understand
how a physically small inductor works will they have any chance of
understanding how a physically long one does.

Which people are those, Roy?

73, Jim AC6XG

"Mark Keith" wrote in message
om...
So far, your tests,
while not being a bugcatcher type coil seem to match my expectations
fairly closely.

I'd like to hear an explanation for ANY current difference across a coil
that is supposedly behaving as a lumped inductor. But the test really
should be for the same type of antenna used in Yuri's discussion; A
physically short antenna, with an electrically long coil, positioned away
from the feedpoint. One misconception here has been about the physical
length of the coil with respect to wavelength. That's not the most relevant
issue, in my opinion. The wire comprising the coil also has a physical
length. The relationship between physical length and electrical length is
velocity factor. The same thing is true for a coil. The velocity factor
for a wire does not go to infinity simply by virtue of the fact that it has
been wound into a coil. This is basically what is being implied when
someone argues that loading coils do not effectively supliment the
electrical length of an antenna.

73, Jim AC6XG