Loading Coils; was : Vincent antenna
 

On Thu, 06 Dec 2007 21:22:09 GMT, Cecil Moore
wrote:

Based on your questions, an ordinary prudent man would
assume that you are just wasting my time. Next thing
is that you will be ragging on me for the number of
postings I had to make in answering your questions.

Well, you didn't answer them all did you? And you didn't really have
anything to show short of those answers until I asked for them, did
you? And you certainly don't have a page of published RESULTs such as
Tom has where the settings and readings are all readily visible and
available, do you?

Of course this laborious, tedious, and painstaking. This is called
the work of science and engineering - or you could just go back to
mooching for validation, the correspondence you commit to that in a
hour far exceeds responding to these few questions over several days.

So, what voltage magnitudes were presented to the inputs of your
scope? or should I consider your silence to a rather ordinary question
as you having hit the limit of your technical depth?

Loading Coils; was : Vincent antenna
 

Dave Heil wrote:

...
"John", I'm sorry you're having difficulties in making it more simple.

So you'd have me believe that you're a MENSA member? Do you attend
under your pseudonym?

Did you, by the way, mean "principles" or did you really intend the word
"principals"? That's very "strang".

Dave K8MN

Dave:

The word is "transparent", you neighbors, you family members
know--attend a self-help group ... it may help others around you.

JS

Loading Coils; was : Vincent antenna
 

On Thu, 06 Dec 2007 21:33:20 GMT, Cecil Moore
wrote:

Richard Clark wrote:
It would be intriguing to discover how your rig drove 5W through the
coil to a 48:1 mismatch.

I already reported more than a year ago that it was
through an autotransformer. I matched the coil Z0
on both the source end and the load end.
So what was the windings ratio?

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

On Thu, 06 Dec 2007 21:33:20 GMT, Cecil Moore
wrote:

Richard Clark wrote:
It would be intriguing to discover how your rig drove 5W through the
coil to a 48:1 mismatch.

I already reported more than a year ago that it was
through an autotransformer. I matched the coil Z0
on both the source end and the load end.
Did you take the input to Channel 1 from this autotransformer?

Loading Coils; was : Vincent antenna
 

John Smith wrote:
Dave Heil wrote:

...
"John", I'm sorry you're having difficulties in making it more simple.

So you'd have me believe that you're a MENSA member? Do you attend
under your pseudonym?

Did you, by the way, mean "principles" or did you really intend the
word "principals"? That's very "strang".

Dave K8MN

Dave:

The word is "transparent"...

Fine. I've changed your sentence to read:

"Means it is acknowledgment of the worth of transparent, practices and
knowledge ..."

you neighbors, you family members
know--...

Me neighbors and me family members will think it reads awfully funny.


...attend a self-help group ... it may help others around you.

No thanks, John. If you're an example of what self-help groups have
done, I believe I'll give it a pass.

If I had to venture a guess, I'd guess you're the wrong guy to explain
what goes on at a MENSA meeting.

Dave K8MN

Loading Coils; was : Vincent antenna
 

Dave Heil wrote:

...
Dave K8MN


Dave:

You remind me of a fellow in the neighborhood when I was a kid, used to
go around talking to himself all the time ... no one paid him much
attention, nowadays would be different of course. :-)

JS

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
"Cecil Moore" wrote in message
. net...
AI4QJ wrote:
Going further, I am still trying to consider how the extra angle can also
be absorbed "into" an impedance discontinuity.
I have started a phasor diagram of it but it is not
finished yet. Maybe a Smith Chart explanation will
work. All lines are lossless.

On a Smith Chart normalized to 100 ohms, lay out the
10 degrees of 100 ohm line from the infinity point,
i.e. the open-circuit point. The reactance value
is tan(90-10) = 5.67. That means the reactance value
is 5.67*100 = -j567 ohms which has to be the value
at the impedance discontinuity.

Now on a Smith Chart normalized to 600 ohms, lay out
the x degrees of 600 ohm line from the zero point
to the point where -j567/600 is located. Read the
number of degrees required. It is Arctan(567/600)
which is equal to ~43 degrees.

The phase shift at the impedance discontinuity is
therefore 90-10-43 = 37 degrees.

I think I see why it no longer surprizes me after going through the smith
chart.
The 100 ohm line (10 degrees) is open. The 600 ohm line has a load impedance
of -j567 ohms, it is not open. The fact that it is terminated with an
impedance (the 100 ohm line) adds degrees on the chart. We should expect the
reactance of the 100 ohm line to add phase angle at the termination similar
to a "discreet component". Hope this makes sense; the smith chart makes it
very clear.



Do you want to work that out mathematically?
73,
Tom Donaly, KA6RUH

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
Cecil Moore wrote:
AI4QJ wrote:
... it is plain and simple "intuitive" once you know that current
changes along the electrical "degree length" in an unloaded antenna,
the same should happen in the degree length loaded coil.
Unfortunately, both sides cannot be right but both sides
are still illustrated as fact in the ARRL Antenna Book.
There's one graphic that shows the drop in amplitude
through a loading coil and another that shows no change.
Apparently, the ARRL doesn't know what happens so they
show both possibilities as technically correct.


Every author has a problem in drawing those diagrams, because we are
trying to draw too many things at the same time: physical height,
electrical height, loading coils, current distributions and voltage
distributions. It doesn't matter which viewpoint we are trying to
illustrate, it is still impossible to draw *all* of those things
truthfully to scale on the same diagram.

When comparing the full quarter-wave against the mobile whip, we have to
choose: do we draw the two antennas to true physical scale; or do we
use an 'electrical' scale of 0 to 90deg? Whichever one we choose, the
scale for the other on becomes grossly distorted, and this is what leads
to confusion.

Every author has trouble with this. Illustrations by different authors
attempt to square the circle in different ways, but none of them ever
can succeed because it fundamentally cannot be done.

ARRL publications are no exception, and a further complication is that
the handbook compilations tend to re-use illustrations from individual
articles by different authors. So please don't read too much into the
mixture of drawing styles - the reasons are often more historical than
technical.

Also, as indicated, the pictures do say 1000 words and it also looks
like W8JI ended up agreeing with you after you pointed out the same
effect at "ON4UN's Low Band DXing", 3rd Edition, on page 9-34.
Unfortunately, it is rumored that W8JI has talked ON4UN
into changing that in the latest edition. I emailed ON4UN
about it but got no reply.

It has been changed. There is no longer any discussion of "degrees",
only "current".

Well, not quite. The 4th edition does use degrees for the electrical
lengths of the plain unloaded sections (which is valid from everyone's
point of view); but it no longer implies that the loading coil
"replaces" any number of degrees.

I don't know the detailed history behind that change, but I do know one
thing: ON4UN is not a man to be swayed by "political" influence. The
change in the 4th edition would be because he was challenged to look
again at the *technical* issues, and then he made up his own mind.



--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Loading Coils; was : Vincent antenna
 

On Dec 6, 1:23 pm, Cecil Moore wrote:
Keith Dysart wrote:
You should also consider a shortened monopole
where lumped elements are used to tune out
the reactance.

Please feel free to pursue that line of
development if you are so inclined.

Since lumped elements do not exist in reality,
they are outside of the scope of real-world
75m mobile loading coils that I am trying to
cover here. I am not proposing a theory of
everything nor do I intend to waste my time
with such. But be my guest.

You have done this before; postulating
explanations that only work in the complexity
of the "real" world, but fail when presented with
the simplicity of ideal test cases.
Then, when the explanations fail on the simple
cases, claiming these cases are not of interest
because the real world is more complex.

It won't fly. Good explanations also work when
presented with test cases from the simpler
world of ideal components.

....Keith

Loading Coils; was : Vincent antenna
 

Dave Heil wrote:
Where's the fulfillment in standing around in a
room full of folks congratulating each other on how smart they are?

It gets the females turned on.
--
73, Cecil http://www.w5dxp.com