On Fri, 03 Oct 2003 18:11:14 GMT, Richard Clark wrote:

On Fri, 03 Oct 2003 12:01:08 -0500, Cecil Moore
wrote:

Richard Clark wrote:
There are one of two possible explanations for your posting:
1. You have not obtained that copy of Chipman that you ordered.
2. You have not read it.
Of course, you can add a third, fourth or fifth... in complete absence
of Chipman's discussion if his material does not agree with your
interpretations.

Richard, you might be interested to know that HP's s-parameter ap note,
AN 95-1, page 22 under Transducer Power Gain, lists the power available
from the source as the (square of the magnitude of the source voltage)
divided by [one minus the (square of the magnitude of the source's complex
reflection coefficient)], i.e. |Vs|^2/(1-|rho|^2)=power available from
the source where presumably source-rho = (Zs-Z0)/(Zs+Z0)

Hi Cecil,

-sigh- even when you offer confirmatory recitations you still miss the
details. There are only 11 pages in Application Note 95-1 and the
material you describe appears on page 4 not 22.

The voltage from the generator is also portrayed in Fig. 3 entitled
"Flow graph of network of Fig. 2." Figure 2, of course, shows the
generator complete with Zs which most here deny exists, or dismiss as
immaterial to any discussion. This is due entirely to their speed
reading past their own sources' discussion that ALL DISCUSSION OF SWR
assumes the source matches the line it feeds. Such an explicit or
implicit relationship is fundamentally required, or the entire text
that they cite is rendered useless gibberish. The most garbled of
those proclamations is that the source Z has no bearing on line SWR.

This same flowgraph is present in many similar works (AN 95-1 is
hardly unique) and being presented early in the work (like Chipman's
similar observation of requiring source-line matching) is skipped so
that the reader (sic) can scrounge their favorite snippet of math and
remove it from its required context. Chipman also presents much the
same treatment in non S-Parameter discussion, but that is quite
obviously from the part unread by the great mass of so called
adherents to his discussion.

However, to give some flexibility to the discussion; such shortfalls
of understanding how SWR works is simply through lack of experience in
the matter. It is understandable when the usual approach to this
topic is taken by employing a transmitter that both specifies its
output at a Z of 50 Ohms and exhibits a Z of 50 Ohms. Given such a
source, the casual debater is lulled into the comfortable illusion of
having been born on third base thinking they hit a triple in the
debate against source Z (no, the count is three strikes).

Simply because they encounter no ill consequence of source mismatch is
NOT evidence of the source Z being immaterial to the process of
measuring SWR. Luck counts for nothing in debate - unless it is
admitted to. None here count themselves lucky - it would diminish
their sense of erudition.

I don't expect there will be any substantive discussion following this
that will change physics to conform to those illusions (my comments
here will not "change their minds").

73's
Richard Clark, KB7QHC

Richard, I'm dismayed with your statements above. Are you really serious? Or are
you just giving Cecil a bad time?

I've been grappling with your last email to me concerning the nature of the
source resistance of RF amps, and as with your statements above, I'm at a loss
as to how to respond, because we are 180 degrees apart on the source resistance
issue. I'm still going to respond to it, but right now I want to address the SWR
issue.

Richard, how can you possibly believe that the output impedance of the source
has any effect on the SWR on a transmission line? The only conditions
responsible for SWR are the Zo of the line and the ZL of the load--nothing else.
I've been bench measuring SWR for more than 50 years, beginning with using the
slotted line before more sophisticated machinery was available. It didn't matter
what the source impedance was, the SWR remained the same, whatever the source.
Ian told it like it is, and so does Walter C. Johnson in his "Transmission Lines
and Networks, Page 100, where he says:

"The steady state ratio Eplus/Eminus was determined in Eq 11 as the reflection
coefficient k...This ratio is determined only by the load and the line, not by
the generator. It is completely unaffected by the quantity kg = (Zg - Zo)/(Zg +
Zo), which is the reflection coefficient seen by an individual
backward-traveling wave as it reaches the generator terminals. ...the latter
affects the steady state solution only on its influence on the sending-end
voltage, i.e., through its influence on the magnitude of the entire solution."

Your reply comments, please.

Walt, W2DU

On Fri, 03 Oct 2003 21:41:15 GMT, Walter Maxwell wrote:


Richard, I'm dismayed with your statements above. Are you really serious? Or are
you just giving Cecil a bad time?

That wouldn't take much to push Cecil off dead center.


I've been grappling with your last email to me concerning the nature of the
source resistance of RF amps, and as with your statements above, I'm at a loss
as to how to respond, because we are 180 degrees apart on the source resistance
issue. I'm still going to respond to it, but right now I want to address the SWR
issue.

Richard, how can you possibly believe that the output impedance of the source
has any effect on the SWR on a transmission line?

Stephen Adam of HP using Beatty describes it quite well. The data you
have by email and has been posted here demonstrates it equally well.
It takes no more than two resistors and a length of line to confirm or
deny. My data confirms it, absolutely no one has offered negative
evidence, simply denials.

The only conditions
responsible for SWR are the Zo of the line and the ZL of the load--nothing else.
I've been bench measuring SWR for more than 50 years, beginning with using the
slotted line before more sophisticated machinery was available. It didn't matter
what the source impedance was, the SWR remained the same, whatever the source.
Ian told it like it is, and so does Walter C. Johnson in his "Transmission Lines
and Networks, Page 100, where he says:

If Walter Johnson was not explicit about it, he was certainly implicit
about the requirement that the source match the line it is driving for
any discussion of SWR. This is so commonplace that no one ever
examines the situation where the source is a mismatch.

Too many here simply flip to the section in their favorite book about
SWR and wholly neglect the fundamentals that present this simple
requirement. I have presented quotes, chapter and verse from Chipman
where he explicitly says as much, and those who hold Chipman have
abandoned discussion rather than refute those quotes or accept their
error. As one scribbler put it I was not going to "change his mind."
I have no doubt of that, such a statement paints one into an extremely
embarrassing corner once having uttered it. One thing I learned as a
Metrologist is that I am always wrong, the significance is in the
degree of error, not the philosophy of sin and the rejection in
ignorance.

Any number of correspondents here "might" have the capacity to simply
repeat my methods and report their data; but absolutely none
demonstrate it. I might be so far in error the meter is pegged, but
the quality of "sneer review" absolves me of sin. ;-)

Hi Walt,

I await your response by email for our last round of discussion. What
is presented above is old material already discussed. There is
nothing new presented by me in it that has not found its way to your
mailbox.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
I have presented quotes, chapter and verse from Chipman
where he explicitly says as much, ...

And I have presented quotes, chapter and verse from Chipman,
that disprove your interpretations of what he said.
--
73, Cecil http://www.qsl.net/w5dxp



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"Richard Clark" wrote in message
...
....................................
Richard, how can you possibly believe that the output impedance of the
source
has any effect on the SWR on a transmission line?

Stephen Adam of HP using Beatty describes it quite well. The data you
have by email and has been posted here demonstrates it equally well.
It takes no more than two resistors and a length of line to confirm or
deny. My data confirms it, absolutely no one has offered negative
evidence, simply denials...................................
73's
Richard Clark, KB7QHC

Richard,

Please humor me. If the source impedance has an effect on SWR, surely an
equation exists that spells that out. Perhaps you can divulge it for
everybody.

Tam/WB2TT

On Sat, 4 Oct 2003 14:26:37 -0400, "Tarmo Tammaru"
wrote:
Richard,

Please humor me. If the source impedance has an effect on SWR, surely an
equation exists that spells that out. Perhaps you can divulge it for
everybody.

Tam/WB2TT


Hi Tam,

I could, but I won't. If you wish to be humored, email me as has
Walt. That venue is far more productive than me providing yet another
citation, its quote, its elaboration, its demonstration at the bench
with data, to only observe it won't "change my mind" sclerosis
mentality exhibited in this forum's sneer review.

I have offered several such matters direct to the point to have those
who could respond from actual verification by observing it in their
copy simply vanish from the debate. As I recall, you did exactly the
same thing with a Motorola application note about source Z that you
never confirmed or denied after introducing it as evidence against my
position.

As for humoring, I find that in the obvious logical disconnects and
exhibiting it here.

73's
Richard Clark, KB7QHC

Walt, W2DU wrote:
"This ratio (reflection coefficient) is determined only by the load and
the line, not by the generator.."

Terman is squarely in Walt`s corner. He says on page 87 of his 1955
edition:
"Reflection coefficient = rho = E2 / E1
= (ZL/Zo) -1 / (ZL/Zo) +1.

No Zsource appears in the equation, only ZL and Zo. " Were it not so,
Terman would have told you!

There is a nice photo of Walt, W2DU in the April 1973 edition of QST.
That`s the edition with (2) Bird wattmeters on the cover. This edition
initiated a series of articles on "Reflections" by Walt.

Best regards, Richard Harrison, KB5WZI

On Mon, 6 Oct 2003 12:51:09 -0500 (CDT),
(Richard Harrison) wrote:
No Zsource appears in the equation, only ZL and Zo. " Were it not so,
Terman would have told you!

Hi Richard,

Terman offers some expansion on your observation in his first footnote
to "Chapter 4 Transmission Lines"
"This material on transmission lines is a review and summary
of those concepts and relations that are most widely held in
radio work. It presupposes at least a little previous familiarity
with the subject, and therefore should not be regarded as a
self supporting presentation of transmission line theory."

Terman loves me this I know!
For "Electronic and Radio Engineering" tells me so.

:-)

73's
Richard Clark, KB7QHC