Revisiting the Power Explanation
 

On Mar 29, 9:29 am, Cecil Moore wrote:
Keith Dysart wrote:
I offer you the same challenge as Cecil, find the error in my
analysis and then compute the correct amount of re-reflection.

We will be glad to do that if you will provide the
impedance value encountered by the reflected wave
with the source turned on. You have not yet done that.
Hint: It doesn't matter what impedance the reflected
wave encounters with the source turned off since
reflected waves are non-existent during that
condition.

The problem is completely solvable with the information
provided.

For examples of the methodology, google
'"lattice diagram" reflection'.

If your alternate methodologies require more information
to solve the problem, then I suggest that such alternate
methodologies are inferior to the standard one.

And to answer your question: 450 Ohms.
And to be more precise, the reflected wave continues for 62
cycles after the current source is turned off.

But truly, do look up lattice diagrams and learn the technique.
The number of problems that you will be able to solve will go
up significantly.

....Keith

Revisiting the Power Explanation
 

On Mar 29, 8:17 am, Cecil Moore wrote:
Dan Bloomquist wrote:
He will completely ignore this and keep insisting on his truth. Me
thinks he is trolling......

Please don't discourage innovation. He can patent his
ten cent method of eliminating reflections and obsolete
the circulator market. Maybe someone should warn
Tektronix.

I would hope that the patent application would be rejected
due to prior art, but given the current state of the patent
office, I am not sure how much confidence I would have.

I expect that Tek is well aware and that were you to examine
the output circuits of their signal generators, there is a
very high probability that you will be able to locate the
voltage source and the 50 Ohm resistor. I know I just found
them on a randomly selected Agilent signal generator.

....Keith

Revisiting the Power Explanation
 

On Mar 29, 9:08 am, Cecil Moore wrote:
Keith Dysart wrote:
Reflection coefficient is actually quite simple.
RC = (Z2-Z1)/(Z2+Z1)
I challenge you to find any reference with a different definition.

Sorry, all my references are at my new QTH but here are
a few from memory:

rho = SQRT(Pref/Pfor) = Vref/Vfor = Iref/Ifor = (SWR-1)/(SWR+1)

Yes, but these are less than useful aren't they. SQRT is
multi-valued so is never any use, and they all express
rho in terms of that which we want to derive rather than
in terms of that which we know. Means we need to know the
answer before we can compute the answer. Ooooopppps.

One of the options for preventing reflections (which can
really mess up the reception of the signal), is matching
at the source.

Yes of course, one can do that with a circulator or pad.

Or a single 10 cent resistor following the voltage or current
source. But I digress. Do look up "lattice diagram".

....Keith

Revisiting the Power Explanation
 

Cecil Moore wrote:

In the past, you have said that redistribution of energy
from canceled waves is absolutely NOT a reflection yet
above you seem to say the redirection is a reflection.
Are you changing your mind about wave cancellation
resulting in reflections?

Hi Cecil -

Please, I've asked you this many times, quote me directly when you
want to refer to something I've said. I am able to explain those
things. I concede that I am unable to explain the convoluted ideas
that you often attribute to me - although I do think I know why you
write them the way you do. For the sake of clarity and simplicity
could we instead try to restrict our dialog to the present discussion,
and include relevant text that is quoted from the post we wish to
comment upon? I think that's how it's customarily done in the newsgroups.

Nothing from the University of Florida contradicts what I said, and I
can find nothing there to object to. My comments were directed
strictly toward some of the things that you wrote. (As a courtesy I
included the text I was referring to). I would like to suggest that
you take more careful note of those areas where your words differ from
those contained in the papers that you cite; in particular, with
regard to interference as a *cause* for the redirection of energy. Do
not infer, as you then risk inferring incorrectly. If you're honest
about it, you will find that interference is the manifestation of a
redirection of energy. It is the form; the envelope of the
distribution. It is a result; the result of the superposition of
waves. Nowhere in the literature will you find anyone describing
interference as a cause of reflection, as you have done. That is
because it is not a factual accounting of the natural phenomena.

Thanks and 73,

Jim AC6XG

Revisiting the Power Explanation
 

Keith Dysart wrote:
But truly, do look up lattice diagrams and learn the technique.
The number of problems that you will be able to solve will go
up significantly.

Since your use of it yielded erroneous results, I think
I will pass. However, it appears to be much like the
S-Parameter analysis which does yield correct results.

An S-Parameter analysis indicates that you have made an
error in the reflection coefficient, s11, looking into
the 450 ohm transmission line. From HP's Ap-Note 95-1,
s11 is defined as the "Input reflection coefficient
with the output port TERMINATED BY A MATCHED LOAD."

You calculated your reflection coefficient with the
output port terminated by a mismatched load. There's
your conceptual error! The reflection coefficient, s11,
at the source is *NOT* the same as the reflection
coefficient at the load.

Have you told anyone else that an emitter follower with
a 450 ohm resistor in the emitter circuit will eliminate
reflections on all 450 ohm transmission lines?
--
73, Cecil, w5dxp.com

Revisiting the Power Explanation
 

Keith Dysart wrote:
I expect that Tek is well aware and that were you to examine
the output circuits of their signal generators, there is a
very high probability that you will be able to locate the
voltage source and the 50 Ohm resistor. I know I just found
them on a randomly selected Agilent signal generator.

If they claim that the 50 ohm resistor eliminates reflections,
as you do, they could be sued for false advertising.
--
73, Cecil, w5dxp.com

Revisiting the Power Explanation
 

Keith Dysart wrote:
Or a single 10 cent resistor following the voltage or current
source. But I digress. Do look up "lattice diagram".

If your "lattice diagram" really tells you to use a
physical reflection coefficient looking one way and
a virtual reflection coefficient looking the other
way within the same analysis as you have done, it
is worthless.
--
73, Cecil, w5dxp.com

Revisiting the Power Explanation
 

Cecil Moore wrote:

Jim Kelley wrote:

Walt doesn't actually indicate 'why' here, either. He is reciting a
set of well known circumstances, and implying that one set of facts
results in another. While the facts are obviously correct, any cause
and effect relationship between them must be inferred.


From his writings in "Reflections" and his postings
here, Walt obviously understands destructive and
constructive interference and the fact that (from
the Florida State University site):

"... All of the photon energy present in
these (cancelled) waves must somehow be recovered or
redistributed in a new direction, according to the
law of energy conservation ..."

In a transmission line we have two directions.
1. Toward the load
2. Toward the source

When the "photon energy" is "redistributed in a new
direction" in a transmission line, I'll bet it
goes in exactly the direction that Walt says it
goes.

If anyone in addition to Cecil thought that I was debating the facts
that Walt presented in Reflections, I apologize. I thought that I had
clearly stated that inferring a causal relationship between certain
sets of those facts had not been demonstrated therein.

73, ac6xg

Revisiting the Power Explanation
 

"Keith Dysart" wrote in message
ups.com...
On Mar 25, 8:23 pm, Cecil Moore wrote:

- The power into the 450 Ohm generator resistor is
38.6 Watts

Just to pick your nit, I think you meant 36.8 Watts. That would be closer to
the 36.7 Watts I obtained using a simplified approach.

Cheers,
John

Revisiting the Power Explanation
 

Cecil Moore wrote:

Here we are arguing semantics, not principles, again.

I was arguing principles, again. I don't bother with semantics (I
lack your expertise there). But I admit that I don't know why you
were arguing. ;-)

73, Jim AC6XG