Richard,

Yes, I took a course from Chipman, but before he published his book. He used
Adler, Chu, and Fano in his class. Reason I mentioned pulses is that most of
what we did in class with reflections involved pulses. You may remember me
giving Roy a hard time a few months ago, because I wasn't used to his way of
thinking. He was right and I was wrong. I don't have the Chipman book.

Tam/WB2TT
"Richard Clark" wrote in message
...
On Wed, 15 Oct 2003 17:18:06 -0400, "Tarmo Tammaru"
wrote:

Richard,

I hope you are not mixing up analog steady state signals and reflections
of
pulses. The re reflection of a signal at a source depends not only on the
impedance, but also on the voltage at the source.

Tam/WB2TT

Hi Tam,

Found within the body of what I posted:

Then of course there is more in Chapter 8
Chapter 8. Section 8.8 "Multiple Reflections."
This material shows the transient analysis and sets up the steady
state analysis already anticipated above in Chapter 9.

Didn't you say you studied under Chipman? This is HIS material, not
my derivations. Again, if I were wrong, there are enough copy holders
here to correct me. That has not come to pass in lo' these several
months.

73's
Richard Clark, KB7QHC

On Wed, 15 Oct 2003 19:53:46 -0400, "Tarmo Tammaru"
wrote:

Richard,

I went to a Bob Pease seminar a few years ago, great guy.

You are missing one of the points of the simulation. I am not trying to
market an SWR meter. I simulated it with ideal parts so that the instrument
is not affecting the reading. How are you going to measure an SWR of 65:1
with a real meter?

Hi Tam,

A very good question. The Metrologist wouldn't, there are better
techniques that are more accurate.

I did change the source impedance, and it did not change the SWR within the
limits of what I could resolve. In addition, as I told Slick a couple of
months ago, I used a real meter (Kenwood SW2000) to measure the SWR with two
different source impedances and two different load impedances, and the
source impedance made no difference.

That too is unremarkable. The difference is not resolved at one point
as I have demonstrated.

I don't know that the Harris transmitter is the same as what was described
in Circuit Cellar. The Harris has no modulators and no linear amplifiers;
just a bank of 65 CW power modules that get switched on and off and
synthesize the desired envelope power at something like a 20 KHz rate. Sort
of a D/A converter that runs at a power level of 50 KW.

No, this misses the mark considerably. The lowest bit rate is half
the Fo of the transmit frequency (typically the bit rate is equal to
the Fo). It is accomplished with a ROM lookup table to achieve the
modulation (much like the Circuit Cellar Ink articles by Don Lancaster
but with significant differences too as his discussion was strictly
CW).

73's
Richard Clark, KB7QHC

Tarmo Tammaru wrote:
There are models for both lossy and non lossy transmission line. I have not
used them, so it might take some learning. I can tell you though that given
a load and transmission line, if you find the Z at the meter with an HP
vector impedance meter, and then put a lumped impedance of that same value
at the meter, you will get the same results.

Not in reality, you won't. Any TV ghosting that exists because of reflections will
disappear when you go to a lumped impedance. And the noise across the lumped
impedance will not be identical to the noise associated with a long transmission line.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

Tarmo Tammaru wrote:
There are models for both lossy and non lossy transmission line. I have not
used them, so it might take some learning. I can tell you though that given
a load and transmission line, if you find the Z at the meter with an HP
vector impedance meter, and then put a lumped impedance of that same value
at the meter, you will get the same results.

Not in reality, you won't. Any TV ghosting that exists because of reflections will
disappear when you go to a lumped impedance. And the noise across the lumped
impedance will not be identical to the noise associated with a long transmission line.

Isn't the point just to test SWR dependency on source impedance?

73, ac6xg

Jim Kelley wrote:

Cecil Moore wrote:

Tarmo Tammaru wrote:
There are models for both lossy and non lossy transmission line. I have not
used them, so it might take some learning. I can tell you though that given
a load and transmission line, if you find the Z at the meter with an HP
vector impedance meter, and then put a lumped impedance of that same value
at the meter, you will get the same results.

Not in reality, you won't. Any TV ghosting that exists because of reflections will
disappear when you go to a lumped impedance. And the noise across the lumped
impedance will not be identical to the noise associated with a long transmission line.

Isn't the point just to test SWR dependency on source impedance?

Just pointing out that the "same results" statement above is a little
too broad. Any deviation in the waves from cycle to cycle due to
modulation and noise shows up as reflected energy.
--
73, Cecil, W5DXP

Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:

Tarmo Tammaru wrote:
There are models for both lossy and non lossy transmission line. I have not
used them, so it might take some learning. I can tell you though that given
a load and transmission line, if you find the Z at the meter with an HP
vector impedance meter, and then put a lumped impedance of that same value
at the meter, you will get the same results.

Not in reality, you won't. Any TV ghosting that exists because of reflections will
disappear when you go to a lumped impedance. And the noise across the lumped
impedance will not be identical to the noise associated with a long transmission line.

Isn't the point just to test SWR dependency on source impedance?

Just pointing out that the "same results" statement above is a little
too broad. Any deviation in the waves from cycle to cycle due to
modulation and noise shows up as reflected energy.

Tarmo's simulation results seem to conflict with Richard's
interpretation of Chipman. Lately you've been leaning toward Richard's
point of view. How does the story end? ;-)

73, Jim AC6XG

On Thu, 16 Oct 2003 10:00:38 -0700, Jim Kelley
wrote:
Cecil Moore wrote:
Tarmo Tammaru wrote:
There are models for both lossy and non lossy transmission line. I have not
used them, so it might take some learning. I can tell you though that given
a load and transmission line, if you find the Z at the meter with an HP
vector impedance meter, and then put a lumped impedance of that same value
at the meter, you will get the same results.

Not in reality, you won't. Any TV ghosting that exists because of reflections will
disappear when you go to a lumped impedance. And the noise across the lumped
impedance will not be identical to the noise associated with a long transmission line.

Isn't the point just to test SWR dependency on source impedance?

73, ac6xg

Hi Jim,

It "was" but through these twists and turns, the point has become a
amorphous blob.

Tam has shown an appreciation for my interpretation of Chipman's work
being focused on transient analysis (it has that in Chapter 8) and a
worry that my data is forced to that criteria - it is not, it is
strictly steady state results and also supported by Chipman's steady
state formulas (found in Chapter 9).

Chapter 8 reveals the obvious state of a transmission line being
mismatched at both ends supporting a bedlam of wave mixings - the
bedlam is simply the artifact of an unknown length in the path,
otherwise it is quite predictable and formulaic. The steady state
solutions presume you know this length (or in his terms, the position
along the line mismatched at both ends) to find the dependency of
measured voltage in terms of source AND load Z.

Cecil, as usual complains without adding anything:
On Wed, 15 Oct 2003 13:43:39 -0500, Cecil Moore
wrote:
Yes, my experiment seemed to support that assertion but you rejected it.
Where this "seeming" was rejected for good reason (or poor reason
depending upon the source ;-) as he had poorly bounded his example (it
did not include the necessary transmission line which evidences the
source Characteristic Z) and he was forever explaining minutia at the
expense of the topic. 600 posting marathons of that kind of
repetition is unnecessary. My data and sources can stand quite well
on their own without the need for rubber crutches.

Speaking of repetition, this is all covered in my new thread
"The Impact of Source characteristic Z upon SWR measurement - the
Galilean Defense re-revisited"
As such there is actually nothing new to add, and absolutely no
holders of Chipman's work have offered any rebuttal - elliptical
criticism notwithstanding. :-)

73's
Richard Clark, KB7QHC

Jim Kelley wrote:
Tarmo's simulation results seem to conflict with Richard's
interpretation of Chipman. Lately you've been leaning toward Richard's
point of view. How does the story end? ;-)

I suspect it ends up with me being mistaken when I said that
instantaneous power is *as* useless as tits on a boar hog. If
the instantaneous power is screwing up the wattmeter readings,
instantaneous power is *more* useless than tits on a boar hog. :-)
--
73, Cecil, W5DXP

Cecil Moore wrote:

Jim Kelley wrote:
Tarmo's simulation results seem to conflict with Richard's
interpretation of Chipman. Lately you've been leaning toward Richard's
point of view. How does the story end? ;-)

I suspect it ends up with me being mistaken when I said that
instantaneous power is *as* useless as tits on a boar hog. If
the instantaneous power is screwing up the wattmeter readings,
instantaneous power is *more* useless than tits on a boar hog. :-)

The story must be like a daytime serial. :-)

73, Jim AC6XG

Richard Clark wrote:
My data and sources can stand quite well
on their own without the need for rubber crutches.

Certainly true about your sources standing well on their own. You
should probably let them. ;-)

73 de ac6xg