On Tue, 25 May 2010 00:45:36 -0700 (PDT), lu6etj
wrote:

To Richard: What I mean is irrelevant :) relevant is what Walt
wanted to say in this sentence: "Because of the absorption of the
pad, the generator sees a nearly perfect match for all load conditions
and all reflected power is lost "
Pllease, tell me what in english means "all reflected power is lost"?
I understood (or translate or interpret) that reflected power is
dissipated in the pad: Is it a bad translation/interpretation?

Hi Miguel,

Your translation is fine.

However, I have no idea what the pad design looks like, nor do I know
the component values. I have calibrated thousands of standard pads at
frequencies up to the 12 GHz. They came in either a Pi design, or a T
design. Their intended use is in system isolation. That is, they
isolate the source from the load OR isolate the load from the source
OR isolate both. For certain component values, you can replace the
"OR" with "AND."

You would isolate the source to keep its frequency and power constant.
You would isolate the load to keep line SWR flat. For this line
application, it is assumed you are calibrating either a load equal or
nearly equal to Zc, or you are measuring RF power. These are the
purpose of pads (they also serve the same function in audio circuits).
Measuring power in the presence of SWR other than 1:1 requires
sophisticated math that is rarely discussed here. Most discussion
usually accepts the presumptions of special cases (which are often
sufficient) and employ less rigorous formulas (which serve well within
the unstated presumptions).

In conventional Kirchoff analysis, the resistor that bridges the
transmission line opening becomes the source (that is Vs and Rs). Pad
design usually makes that one resistor for the Pi pad, or two
resistors for the T pad. If you are working in accurate and precise
measurement, you then account for the input (source) resistance in
parallel/series combinations. This second computation is the numeric
analysis of isolation. The higher the ratios of these pad resistors,
the higher the isolation.

It doesn't normally serve any use to have the pad apparent resistance
(what I called Rs above) different from Zc or from Zload, but as this
component is a sacrificial one, the designer may choose to put it to
use to achieve a desired goal. Pad performance suffers with heat due
to energy combinations that come from multiple/single sources.

73's
Richard Clark, KB7QHC

On 25 mayo, 12:51, Richard Clark wrote:
On Tue, 25 May 2010 00:45:36 -0700 (PDT), lu6etj
wrote:

To Richard: What I mean is irrelevant :) *relevant is what Walt
wanted to say in this sentence: *"Because of the absorption of the
pad, the generator sees a nearly perfect match for all load conditions
and all reflected power is lost "
Pllease, tell me what in english means "all reflected power is lost"?
I understood (or translate or interpret) that reflected power is
dissipated in the pad: Is it a bad translation/interpretation?

Hi Miguel,

Your translation is fine.

However, I have no idea what the pad design looks like, nor do I know
the component values. *I have calibrated thousands of standard pads at
frequencies up to the 12 GHz. *They came in either a Pi design, or a T
design. *Their intended use is in system isolation. *That is, they
isolate the source from the load OR isolate the load from the source
OR isolate both. *For certain component values, you can replace the
"OR" with "AND."

You would isolate the source to keep its frequency and power constant.
You would isolate the load to keep line SWR flat. *For this line
application, it is assumed you are calibrating either a load equal or
nearly equal to Zc, or you are measuring RF power. *These are the
purpose of pads (they also serve the same function in audio circuits).
Measuring power in the presence of SWR other than 1:1 requires
sophisticated math that is rarely discussed here. *Most discussion
usually accepts the presumptions of special cases (which are often
sufficient) and employ less rigorous formulas (which serve well within
the unstated presumptions).

In conventional Kirchoff analysis, the resistor that bridges the
transmission line opening becomes the source (that is Vs and Rs). *Pad
design usually makes that one resistor for the Pi pad, or two
resistors for the T pad. *If you are working in accurate and precise
measurement, you then account for the input (source) resistance in
parallel/series combinations. *This second computation is the numeric
analysis of isolation. *The higher the ratios of these pad resistors,
the higher the isolation.

It doesn't normally serve any use to have the pad apparent resistance
(what I called Rs above) different from Zc or from Zload, but as this
component is a sacrificial one, the designer may choose to put it to
use to achieve a desired goal. *Pad performance suffers with heat due
to energy combinations that come from multiple/single sources.

73's
Richard Clark, KB7QHC

Dear friends

Sincerely it was not my desire to vivify old polemics but to tell the
truth, eight years it is a lot of time for not having arrived to a
consent!; hey boys this is science non religion! We must have a way
of leaving the well! :)

Is not possible you are using different models to describe an only one
phenomenon?, as looking at the same cat from their muzzle or from his
tail believing each one his cat is the true or real "cat" :)

I finished reading Cecil's article (http://www.w5dxp.com/nointfr.htm)
and I took of his example that of the 12,5 ohm load. I took a Smith's
chart and obtained the line input impedance, then I applied basic
circuits theory and I obtained the same value of power dissipated in
Rs -exactly-
As I see, if we use a simple electric model of generators and
impedances to solve the problem (maybe like Owen suggests), we can
explain the dissipation in Rs without appealing to any reflected power
returning into the generator because the interference phenomenon that
Cecil describes takes place to form the impedance that generator
see.
Or alternatingly the dissipation can be described by means of the
equations that Cecil shows in its page. In such case we should
consider both powers (direct and reflected) operating simultaneously
on generator resistance. Same cat, different points of view... :)

Perhaps my vision is naive but this situation reminds me an example of
Sears and Semansky book "University physics" (third edition) where he
explains that energy can be thought as not transported by charges in
movement, but for the electromagnetic field associated to them. Last
is a little hard to see -Poynting vector et al- :) but it is
applicable.

Always has been a pleasure for me to read you. I have learneing very
much from your enthusiastic discussions. You made me think of things
that I never thought without your help. Thank you.

Miguel Ghezzi . LU6ETJ

PS: Meanwhile I take the Owen advice and I am still studying!

On Tue, 25 May 2010 20:41:45 -0700 (PDT), lu6etj
wrote:

eight years it is a lot of time for not having arrived to a
consent!

Hi Miguel,

You got on this train rather late if all you see is eight years of it.
The circular references have entertainment value - so did vaudeville.

73's
Richard Clark, KB7QHC

On 26 mayo, 02:26, Richard Clark wrote:
On Tue, 25 May 2010 20:41:45 -0700 (PDT), lu6etj
wrote:

eight years it is a lot of time for not having arrived to a
consent!

Hi Miguel,

You got on this train rather late if all you see is eight years of it.
The circular references have entertainment value - so did vaudeville.

73's
Richard Clark, KB7QHC

Hi Richard

You got on this train rather late if all you see is eight years of it.

I am not mean that!

I clearly said=

"Always has been a pleasure for me to read you. I have learning very
much from your enthusiastic discussions. You made me think of things
that I never thought without your help. Thank you."

Miguel

On May 26, 2:33*pm, lu6etj wrote:
On 26 mayo, 02:26, Richard Clark wrote:

On Tue, 25 May 2010 20:41:45 -0700 (PDT), lu6etj
wrote:

eight years it is a lot of time for not having arrived to a
consent!

Hi Miguel,

You got on this train rather late if all you see is eight years of it.
The circular references have entertainment value - so did vaudeville.

73's
Richard Clark, KB7QHC

Hi Richard

You got on this train rather late if all you see is eight years of it.

I am not mean that!

I clearly said=

"Always has been a pleasure for me to read you. I have learning very
much from your enthusiastic discussions. You made me think of things
that I never thought without your help. Thank you."

Miguel

Cecil, have forgotten that because the source resistance of the RF
power amp is non-dissipative, none of the reflected power is absorbed
therein?

Walt

On May 26, 1:56*pm, walt wrote:
Cecil, have forgotten that because the source resistance of the RF
power amp is non-dissipative, none of the reflected power is absorbed
therein?

Actually, this discussion is based on an example introduced by W7EL
which assumed a 50 ohm source resistor in his "food for thought,
forward and reflected power" article posted on his web page. The
source resistance of an actual RF power amp doesn't matter. W7EL's
example specified a 50 ohm resistor as the source impedance.

http://eznec.com/misc/Food_for_thought.pdf
--
73, Cecil, w5dxp.com

On Wed, 26 May 2010 11:33:08 -0700 (PDT), lu6etj
wrote:

"Always has been a pleasure for me to read you. I have learning very
much from your enthusiastic discussions. You made me think of things
that I never thought without your help. Thank you."

Hi Miguel,

You are welcome.

My comments (beyond your quote above) were in regard to you observing
the amount of time Walt's topic has been under discussion. In fact,
the agony of source resistance has been painfully with us for as long
as newsgroups could support the noise bandwidth.

As dangerous as unasked-for advice is, prepare something at your bench
to measure all these contentious issues for yourself. Force the
issues that are only being discussed rather than measured. Discover
the roots of what used to be a "hands on" avocation. Learn the
practical reality in relation to the academic meaning. Discover the
first principles by making mistakes and having failures that you can
correct in front of you, instead of being assisted by an "expert."
Compare results with like-minded bench workers who can perform the
same examinations you are doing.

This is what Walt did - many times. His bench work eclipses ALL
discussion of theory. The irony that inhabits this is that his bench
work may even eclipse his own explanations. Absolutely no one else
has dared to slide up to the bench to demonstrate that, however. The
level of "critique" is much like ants scattering at the feet of a
giant.

There is a lot of math thrown against the wall to prove something. It
may or may not be the same thing. What it does prove is:
"Models are doomed to succeed."
This is demonstrated here at least once a week on average, and is even
held up as a hallmark of hazing, initiation, or anti-intellectual
snobbery. Math/Models/Simulations/Theories serve many religious wars.

73's
Richard Clark, KB7QHC

On 26 mayo, 18:44, Richard Clark wrote:
On Wed, 26 May 2010 11:33:08 -0700 (PDT), lu6etj
wrote:

"Always has been a pleasure for me to read you. I have learning very
much from your enthusiastic discussions. You made me think of things
that I never thought without your help. Thank you."

Hi Miguel,

You are welcome.

My comments (beyond your quote above) were in regard to you observing
the amount of time Walt's topic has been under discussion. *In fact,
the agony of source resistance has been painfully with us for as long
as newsgroups could support the noise bandwidth.

As dangerous as unasked-for advice is, prepare something at your bench
to measure all these contentious issues for yourself. *Force the
issues that are only being discussed rather than measured. *Discover
the roots of what used to be a "hands on" avocation. *Learn the
practical reality in relation to the academic meaning. *Discover the
first principles by making mistakes and having failures that you can
correct in front of you, instead of being assisted by an "expert."
Compare results with like-minded bench workers who can perform the
same examinations you are doing.

This is what Walt did - many times. *His bench work eclipses ALL
discussion of theory. *The irony that inhabits this is that his bench
work may even eclipse his own explanations. *Absolutely no one else
has dared to slide up to the bench to demonstrate that, however. *The
level of "critique" is much like ants scattering at the feet of a
giant.

There is a lot of math thrown against the wall to prove something. *It
may or may not be the same thing. *What it does prove is:
* * * * "Models are doomed to succeed."
This is demonstrated here at least once a week on average, and is even
held up as a hallmark of hazing, initiation, or anti-intellectual
snobbery. *Math/Models/Simulations/Theories serve many religious wars.

73's
Richard Clark, KB7QHC

Hi Richard. thanks for your reply.

I recognize so much the Walter's work as I said in my initial post.
"Another look at reflections" was one of the my most appreciated
readings of my early days as student and Ham.
But without wishing to be flattering ("adulador" in spanish), I feel
in debt with much others works from you (all) (I do not give more
names to not commit injustice omiting anyone).
I believe you are a gifted, brilliant, intelligent and supportive Hams
sharing your knowledge and experience with us. For that, I am/we are
indebted to all of you :)

However, I believe for all reasons given above, you will be capable to
arrive to a good technical/scientific consensus about the matter. We
trust in your ability and capacity to get it.
This is very important for us because not all are capable to develop
theory from empirical working and we need your agreement to study
things that in my experience are very difficult to grasp even for
university graduates...

73

Miguel Ghezzi - LU6ETJ

On Thu, 27 May 2010 17:03:28 -0700 (PDT), lu6etj
wrote:

However, I believe for all reasons given above, you will be capable to
arrive to a good technical/scientific consensus about the matter. We
trust in your ability and capacity to get it.

Hi Miguel,

A nice sentiment, but even the most silvered authorities disagree. One
has only to look at the relativist camp vs. the quantum camp in
nuclear physics.

This is very important for us because not all are capable to develop
theory from empirical working and we need your agreement to study
things that in my experience are very difficult to grasp even for
university graduates...

Then, this will be dissappointing. University is for finding your own
way, and that does not come without regrets. There's a maxim that
applies he
"If you haven't failed, you are not trying hard enough."

73's
Richard Clark, KB7QHC

On May 25, 10:41*pm, lu6etj wrote:
Is not possible you are using different models to describe an only one
phenomenon?, as looking at the same cat from their muzzle or from his
tail believing each one his cat is the true or real "cat" :)

Dr. Corum tells us what the problem is: "Lumped circuit theory fails
because it's a *theory* whose presuppositions are inadequate. Every EE
in the world was warned of this in their first sophomore circuits
course. ... The engineer must either use Maxwell's equations or
distributed elements to model reality. ... Distributed theory
encompasses lumped circuits and always applies."

In particular, *energy flow* is not addressed at all in the lumped
circuit model. Some RF gurus are so confused that they imply that
there is no Poynting vector power density in reflected waves. Their
basic error (for the past 8 years) is that they believe there is no
mechanism outside of the reflection model that can redistribute the
reflected energy. But what can happen to reflected energy has been
known for decades in the field of optical physics. The reflection that
one sees in a mirror contains an ExH power density that activates
one's human retina. Waves cannot exist without energy. Standing waves
cannot exist without forward and reverse traveling waves. That some
otherwise knowledgeable and influential RF gurus deny the reality of
such is really sad.

What they are missing is simple. The FSU web page describes how wave
cancellation redistributes the reflected energy back toward the load
from what is essentially a Z0-match. The redistribution of reflected
energy due to wave cancellation is technically NOT a re-reflection
since it involves destructive interference between TWO waves. When the
RF gurus broaden their knowledge base to include wave cancellation,
they will alleviate their ignorance on how reflected energy is
redistributed back toward the load. That knowledge can be obtained
from any good optics reference book including "Optics", by Hecht and
"Principles of Optics", by Brown and Wolf. Until those gurus admit to
themselves that they are not omniscient, the argument will continue.

I finished reading Cecil's article (http://www.w5dxp.com/nointfr.htm)

Remember that article describes the two special cases where the two
superposed waves are 90 degrees apart and therefore do not interfere
with each other, i.e. no wave cancellation exists. I have not yet
written the other two articles about constructive and destructive
interference.
--
73, Cecil, w5dxp.com