Roy,

I am not sure Richard understands this, but I am simulating an actual
circuit. That is, the input to the simulator is a schematic diagram of the
circuit. With the present setup, a transient analysis is done by calculating
the waveform at 100 point for each cycle of the waveform. I could use more
sampling points, but it would run longer.

Tam/WB2TT
"Roy Lewallen" wrote in message
...
Tarmo Tammaru wrote:
"Richard Clark" wrote in message
...

The mythical lurkers should note all the effort that goes into a
perversion of a vastly simpler exercise that could be conducted easily
at the bench; and the reason for not going to the bench? Some infer
too hard (by lack of effort); others explicitly state it doesn't
matter (through reams of virtual pages gusting on about its
inconsequence); and yet others deferring it with excuses it demands
too much time for the effort.


Richard,

A simulation of a circuit is better than the "bench". I have components
with
0% tolerance, 0 length leads, no parasitic components, and no power
limits.
It does precisely what a physical meter is a compromise of.

It does not care whether there is a piece of coax connected to the
circuit
or not. Neither does the physical meter. Both find SWR by calculating
the
deviation of the load impedance from 50 Ohms.

Tam/WB2TT

And, consequently, the results you get should be exactly the same as
those of us using equations rather than modeling simulations get. I
don't see any reason why people who don't believe the equations would
believe simulation results.

Roy Lewallen, W7EL

"Reg Edwards" wrote in message
...
But the situation is even worse than that! The so-called SWR meter cannot
even tell you the all-important sign of the deviation - just that a
deviation in some unknown direction exists.
Reg, G4FGQ

Reg,

Actually the information we need is there, but not displayed. For RL R0,
the magnitude of the voltage sample is greater than the current sample. For
RLR0, the magnitude of the current sample is greater. For a 50 Ohm meter,
the two samples are, of course, equal for the case where R0=50 Ohms. To
display this information in common meters would be difficult, because the
voltage sample is with respect to ground, but the current sample appears as
a floating differential signal, with the voltage sample as a common mode
signal.

All of this is simple to do in simulation, because I can use opamps with
1000V common mode range, and arbitrarily wide bandwidth.

Tam/WB2TT

"Richard Clark" wrote in message
...
On Tue, 14 Oct 2003 20:32:33 -0400, "Tarmo Tammaru"
wrote:
Hi Tam,

Simulations conform to nature, they do not enforce their own rules and
try to mimic someone's notion of "what should be."


No, I built an actual circuit, using perfect components.

If it does not care about coax, this kind of response is an implicit
statement of its being "too hard to manage" so-forget-about-it
approach to changing the problem to suit the answer. In other words,
a model of what? Nothing closer to the original than the oft-quoted
humor of "What is the definition of an elephant? A mouse built to
government specification!"

If you want, I will send you a PDF of the schematic.


And so I return to the statement I objected to:
source impedance does not affect SWR.
which is shown no where to have been attempted, and is shown nowhere
to have been proven. What SWR? Where?

I measured the SWR at the point Cecil proposed. I don't recall him
specifying a transmission line either.



I note the total absence of technical answers to these specific
questions with proofs of unrelated doodling offered instead.

You want equations, OK.
For a meter balanced at 50 Ohms, we have
1) VF= V + 50I
2) VR=V - 50I

3) To keep this simple, let the load be resistive, and equal to R. Now, I =
V/R.

4) Let's define a G=(VP + VR)/(VP - VR).

Plugging 3 into 1 and 2, and then 4, we get

G= [V + (50V/R) + V - (50V/R)]/ [V + (50V/R) - (V- (50V/R)]

G= 2V/[100(V/R)]

5) G=R/50

But 5 is precisely the definition of SWR. Therefore G==SWR. Your Bird
wattmeter does exactly this same thing.

The condescension of
A simulation of a circuit is better than the "bench".
is absurd, especially when that same simulation fails to confirm bench
experience. I would challenge you to offer the testimony of any
single (credible) author of a simulator to stand by this profundity.

I hate to tell you this, but all complicated designs have been proven in by
simulations for years. Nobody builds a Pentium CPU before they make a chip.
They simulate it.

I note this last effort of yours is one of several iterations - which
simulation was the most perfect? The first or the last? Who is to
know? How is it to be known? Simulation did not describe to you what
you had to change in the simulation to achieve Nirvana. None of your
rationale for change emanated from the data, it sprang from the
experience of someone's bench providing superior results. If this
exercise is so much better, it should have taken only one pass to
accomplish. The negation of that is found in the failed attempts.

In analog simulations there is a tradeoff between accuracy, and how long it
takes. Also, I pointed out that I added opamps to the model so I would not
be loading down the line with 10K resistors.

Thus the assertion of:
A simulation of a circuit is better than the "bench".
has been shown to be absurd through successive failures by the author
of that statement.

Just for an example, I can make the source impedance anything I want. Do
that on your bench.



As I have offered before, there is humor to be found in the disconnect
and this *******ization by Cecil reigns supreme in examples. But to
its credit, it keeps me amused and offers considerable fodder for the
mythical lurker to observe where the logical landmines are (or in
counting the field's litter of amputees attempting pirouettes). ;-)

You have been talking to the Easter Bunny again.
Tam/WB2TT

73's
Richard Clark, KB7QHC

On Wed, 15 Oct 2003 06:58:10 -0500, Cecil Moore
wrote:

Richard Clark wrote:
As I have offered before, there is humor to be found in the disconnect
and this *******ization by Cecil reigns supreme in examples.

Hmmmmm, that "*******ization by Cecil" supports your side of the
argument, Richard. Would you rather it not support your argument?

Hi Cecil,

No, it does not, and your poor attention to the details doesn't even
come close to the discussion I have offered. *******ization means an
illegitimate substitute and your speculation fully qualifies.

73's
Richard Clark, KB7QHC

On Wed, 15 Oct 2003 10:52:56 -0400, "Tarmo Tammaru"
wrote:


"Richard Clark" wrote in message
.. .
On Tue, 14 Oct 2003 20:32:33 -0400, "Tarmo Tammaru"
wrote:
Hi Tam,

Simulations conform to nature, they do not enforce their own rules and
try to mimic someone's notion of "what should be."


No, I built an actual circuit, using perfect components.

Built? How droll.

If it does not care about coax, this kind of response is an implicit
statement of its being "too hard to manage" so-forget-about-it
approach to changing the problem to suit the answer. In other words,
a model of what? Nothing closer to the original than the oft-quoted
humor of "What is the definition of an elephant? A mouse built to
government specification!"

If you want, I will send you a PDF of the schematic.

And a schematic proves you have "built" a mouse to government
specifications? The amusement "builds."


And so I return to the statement I objected to:
source impedance does not affect SWR.
which is shown no where to have been attempted, and is shown nowhere
to have been proven. What SWR? Where?

I measured the SWR at the point Cecil proposed. I don't recall him
specifying a transmission line either.

You didn't measure anything, you modeled it, and you didn't answer the
question, instead using Cecil's "proposed point" as the scapegoat.
Soon the EE departments across the land will be teaching SWR
measurements to each component lead in a circuit if they follow this
"logic." This syllabus is suitable only for the Laughing Academies.


I note the total absence of technical answers to these specific
questions with proofs of unrelated doodling offered instead.

You want equations, OK.

5) G=R/50

But 5 is precisely the definition of SWR. Therefore G==SWR. Your Bird
wattmeter does exactly this same thing.

An appeal to a bench top instrument? Funny how models at some point
eventually require this anchor that the users insist is unnecessary.
Funnier still is that this whole affair arose of its failure in the
face of inappropriate application, and then the "model" inverting the
logic to prove the inappropriateness was in fact appropriate, which in
turn brings us back to the Bird to substantiate the model.

Next, models of earth, by using short rulers laid against the ground,
will prove it flat. :-)


The condescension of
A simulation of a circuit is better than the "bench".
is absurd, especially when that same simulation fails to confirm bench
experience. I would challenge you to offer the testimony of any
single (credible) author of a simulator to stand by this profundity.

I hate to tell you this, but all complicated designs have been proven in by
simulations for years. Nobody builds a Pentium CPU before they make a chip.
They simulate it.

Aw c'mon Tam, you don't hate to tell me that at all! Nobody built a
4004 before they made it? Your argument is simply the artifice of
myopic reasoning to force the question to the answer.


I note this last effort of yours is one of several iterations - which
simulation was the most perfect? The first or the last? Who is to
know? How is it to be known? Simulation did not describe to you what
you had to change in the simulation to achieve Nirvana. None of your
rationale for change emanated from the data, it sprang from the
experience of someone's bench providing superior results. If this
exercise is so much better, it should have taken only one pass to
accomplish. The negation of that is found in the failed attempts.

In analog simulations there is a tradeoff between accuracy, and how long it
takes. Also, I pointed out that I added opamps to the model so I would not
be loading down the line with 10K resistors.

Not responsive to the question at all. Which Model was the most
perfect in a world where all Models are perfect?

Your response (anticipated) begs the question: Why the need for 10GHZ
GBW Op Amps when a diode, resistor, capacitor, and suitable Radio
Shack meter could do the job? You beg accuracy (the common refuge of
many here so untutored in the subject) when you demonstrate poor
method of accomplishing the measure. Nothing demands 10K resistors
except to satisfy the answer force fitting the question around it.

In my career in Metrology, I measured Hi-Q circuits long, long before
10GHz (or 100MHz, or 1MHz) GBW devices. The poverty of experience is
not a suitable argument proving what was not measured.

Thus the assertion of:
A simulation of a circuit is better than the "bench".
has been shown to be absurd through successive failures by the author
of that statement.

Just for an example, I can make the source impedance anything I want. Do
that on your bench.

In fact I demonstrated this exactly to this specific point, but of
course that evidence is ignored to once again fit the question around
the answer "built." Just like discarding the transmission line that
doesn't fit the answer achieved, discarding my data to charge me with
not having the capacity to do it is of similar caliber.


As I have offered before, there is humor to be found in the disconnect
and this *******ization by Cecil reigns supreme in examples. But to
its credit, it keeps me amused and offers considerable fodder for the
mythical lurker to observe where the logical landmines are (or in
counting the field's litter of amputees attempting pirouettes). ;-)

You have been talking to the Easter Bunny again.
Tam/WB2TT

73's
Richard Clark, KB7QHC


As for equations. It is eminently obvious no "critics" here are going
to utter a line of such work that fills an entire chapter from
Chipman, and is found distributed across other chapters in its
introduction. Even the Easter Bunny would be loath to cite Chipman to
prove Chipman wrong. Talk about impeaching your sources. :-)

I have the advantage here. I could be wrong. I could be shown to be
in error in my reading of Chipman. It hasn't happened. There are
many here who hold copies of his work. There are none who dispute my
recitation at any specific point, nor do they offer statements in his
text expressed by him contradicting my interpretation. My advantage
is that so many here are either lazy if I am wrong, or worse, too
ashamed if I am right. And for such a small matter too. ;-)

It is indeed a poor model that cannot replicate results found from the
math source offered for the unaltered question posed; but the flat
earth society endures and the world tolerates (humors) their model.

73's
Richard Clark, KB7QHC

Actually, several people (W8JI among them) have measured the output
impedance of common amateur linear amplifiers by at least a couple of
methods. The most credible measurements show, interestingly, a value
very close to 50 ohms when the amplifier is adjusted for normal operation.

[sotto voce] "and yet it moves" - updated to

Of course, it doesn't really matter, but people continue to make a big
deal out of it.

Roy Lewallen, W7EL

On Wed, 15 Oct 2003 06:48:09 -0500, Cecil Moore
wrote:

Richard Clark wrote:
A transmitter is loaded with two components and a meter placed between
them - woohah!

Richard, I've got Chipman's book now. Where does he say that SWR
depends upon the source impedance. He does describe a localized
resonance effect within a transmission line. Are you saying the
source impedance is a causal parameter for that localized resonance
effect?

Not arguing with you - just still trying to understand what you
are saying.

Hi Cecil,

Your "not arguing" is as passive as your not looking at either the
text nor referencing my having answered this time and time befo

Chapter 3. Fig. 3-1 "Complete transmission line circuits"

Chapter 3. Fig. 3-2 "Equivalent circuits"

These may be resourced to the SAME answers to you Oct. 3.

Also introduced to you:

Chapter 4. Section 4.4 "Reflected Waves"
which describes the commonplace that any line terminated in an
impedance not the same as the characteristic of the line produces
reflections. This, of course, is something that you have no differed
upon, but on the same hand, neither have your carried it to its
logical conclusion which this section introduces as material being
prepared for Chapter 8. Also note that this section explicitly
references the figures described above.

The cogent point offered by Chipman (and has been reported here by me
as a quote), that when a reflection occurs at the load and returns to
the source:
"in general will be partially re-reflected there, depending on
the boundary conditions established by the source Impedance Zs."
It should come as no surprise that this combination of source power
and re-reflected power will produce a resultant that is dependant upon
the length of the line. This conforms to the simple mechanics of
interference which has been so ill-abused here.

Also quoted he
Chapter 8. Section 8.2 "The practical importance of standing
wave observations."
where in paragraph (e)
"... when the source impedance is not equal to the characteristic
Impedance of the line, this conclusion does not apply. The
General case is discussed more fully in Chapter 9."

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.

Chapter 9. Section 9.10 "Return loss, reflection loss, and
transmission loss."

This gives an equation (which modelers fail to appreciate in lesser
work) that answers my earlier Challenge of how to reveal the
Transmitter's characteristic Z through the measure of line loss due to
mismatch at both ends of the line.

Chapter 10. Section 10.7 "Resonance curve methods for impedance
measurement."

This offers how the voltage variation ALONG a transmission line is
function of BOTH source Z and load Z. This was demonstrated by my
bench example. Roy wanted that expressed as a formula specific to
SWR, but as he stated he wasn't going to have his mind changed, I
deemed it unnecessary to extend the math to perform that chore, and
especially when this assemblage of Chipman's work is both unread, and
when offered in recitation is unresponded to. Such is the quality of
"peer review."

Chipman is but a single source that I have offered, but he does have a
following and his material is written to be accessible.

As I have stated, my advantage is that I could be proven wrong by my
interpretation, but none choose to do so with their own readings from
the same source.

The question that remains:
Do you abandon the topic like the others?

73's
Richard Clark, KB7QHC

Tarmo Tammaru wrote:
I measured the SWR at the point Cecil proposed. I don't recall him
specifying a transmission line either.

Everything was connected through three foot lengths of RG-400.
According to the guys over on sci.physics.electromag, that is a
long enough length to force a Z0 of 50 ohms upon the distributed
circuit. Is it easy for you to install some coax in your simulation?
--
73, Cecil http://www.qsl.net/w5dxp



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Richard Clark wrote:

wrote:
Hmmmmm, that "*******ization by Cecil" supports your side of the
argument, Richard.

No, it does not,

Yes, it does, even though you may not realize it. The "resonance effect"
localized energy exchange reported by Chipman exists worse case at a
conjugate match point where the reactances are at maximum values. Hopefully,
you realize that a conjugate match depends upon the source impedance, which
supports your argument.
--
73, Cecil http://www.qsl.net/w5dxp



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The point is, that the simulator determines the voltage and current at
each instant by solving the differential equations which are well known
to us. Solving those very same equations for transmission lines and
loads, then mathematically moving to the steady state frequency domain,
gives us the familiar transmission line equations we use to calculate
such things as SWR. So you're really doing the same thing as people who
are calculating SWR from common equations. Doing the modeling does show
that the common equations are being applied properly, but otherwise it
should produce the same answer. The conclusion that SWR is affected by
source impedance isn't supported by the theory established and verified
in around 100 years of use -- that same theory that leads to the
equations used by your simulator and to the common transmission line
equations we use, so both tell us it isn't so. As usual, I'm having
trouble understanding what Richard is saying, but he seems to be basing
his premise solely on measurements he's made. If that's so, it would be
foolish to toss out a hundred years of well-established theory on the
basis of his measurements. As far as I can tell, he's offered no
rational, logical, or mathematical explanation for his anomalous
results, only taunts and insults, so the only rational conclusion is
that there's something amiss with his measurement technique or
instrumentation. Re-proving well-established theory every time a
measurement seemingly contradicts it is a fool's errand of the first
magnitude. Time is virtually always better spent in determining what's
wrong with the measurements.

Roy Lewallen, W7EL

Tarmo Tammaru wrote:
Roy,

I am not sure Richard understands this, but I am simulating an actual
circuit. That is, the input to the simulator is a schematic diagram of the
circuit. With the present setup, a transient analysis is done by calculating
the waveform at 100 point for each cycle of the waveform. I could use more
sampling points, but it would run longer.

Tam/WB2TT

Richard Clark wrote:
I have the advantage here. I could be wrong. I could be shown to be
in error in my reading of Chipman. It hasn't happened. There are
many here who hold copies of his work. There are none who dispute my
recitation at any specific point, nor do they offer statements in his
text expressed by him contradicting my interpretation. My advantage
is that so many here are either lazy if I am wrong, or worse, too
ashamed if I am right. And for such a small matter too. ;-)

Your biggest problem is that you absolutely refuse to allow anyone to
agree with you.
--
73, Cecil http://www.qsl.net/w5dxp



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