On Mar 21, 11:48 pm, Cecil Moore wrote:
Keith wrote:
For some years now, you have been arguing the reality of 'reverse
power'.

Nope, for the last few years I have been arguing the
reality of a reverse or reflected EM energy wave. Energy
is what moves and is the essence of an EM wave moving
at the speed of light. All I am arguing is the validity
of the distributed network reflection model, something
that has stood the test of time for a century or so.

But there are some challenges to the premise of 'reverse power':
- where does the 'reverse power' go?
- why does the change in dissipation of a generator when 'reverse
power' changes depend more on the design of the generator than
on the magnitude of the 'reverse power'?

Reflected energy waves obey the principles of conservation
of energy and superposition some of which is discussed in
my WorldRadio energy article at:

http://www.w5dxp.com/energy.htm

I would suggest that you try trodding this path. Make a list of
phenomena that you think are explained by 'reverse power'.

Actually, "reflected energy" rather than "reverse power".
Here is very close to an experiment we did at Texas A&M
during the 50's. We observed the ghosting and the professor
explained reflected energy waves to us.

TVSG-----1000 feet 450 ohm ladder-line---75 ohm TV RCVR

If the TV Signal Generator is not equipped with a circulator
to get rid of the reflected energy wave, ghosts will appear on
the TV RCVR. The ghosts are exactly where they should be if
reflected wave energy exists. How would you explain the
ghosting?

Ghosting is explained by reflected voltages and currents.

I notice that you frequently use this example, unfortunately
never completing the analysis.
Since you leave it unspecified, let me choose the
output impedance of the TVSG to be 450 Ohms. Now there is
'reverse power' in the ladder line but no ghosts. Where did
the 'reverse power' go such that it does not produce ghosts?

If it is re-reflected, then it is a delayed copy of the original,
i.e. a ghost. So where does it go? Seems to me there is only
two ways and the way that does not produce a ghost is into the
generator, so we need an accounting of this power within the
generator, iff it is real power.

Of course there is no issue once you let go of the notion of
'reverse power'. The reverse voltage and current pass into
the generator since the generator is matched to the line and
nothing is reflected.

And since multiplying reverse voltage by reverse current does
not, in general, produce a real power, there is no power to
account for.

But, again, to argue that 'reverse power' is real, it becomes
necessary to explain where it went.

You could start by providing a list of phenomena for which you
think the reality of 'reverse power' is the only viable explanation
and offer a willingness to learn about alternative explanations.

Please see above. And please abandon the words, "reverse
power" in favor of reverse or reflected EM energy wave.

Love to, once it is no longer used as an explanation for these
phenomena. Simply changing the name to something else won't help.

....Keith

On Fri, 23 Mar 2007 19:30:56 GMT, Walter Maxwell
wrote:

I don't understand what you mean by 'taking only one
of two degrees of the 360.'

Hi Walt,

I offered:
they take only one or two degrees of the 360.

Arguments that are confined only at 0 or 180 (the one OR two degrees)
and are submitted as proofs as though they boxed the compass. All too
often I've seen one condition (at one phase angle) offered as a
negation of internal heating to prove the source lacks its own
internal resistance. When I've taken exactly the same circuit and
explored the 180th degree alternative, I've demonstrated melt-down
clear and simple. The dissipation of energies does not always lead to
this consequence, but if we were to average the analysis over a
complete 360 degrees, we can only arrive at the obvious evidence of
resistance and calories expended.

But even for coherent reflections, if the PA tank circuit has very low loss
for incident power (which it does), why does it not have ~ equally low loss
for load reflections of that power? Such would mean that load reflections
would pass through the tank to appear at the output element of the PA, where
they can add to its normal power dissipation.

The paragraph above seems to me to imply that RF doesn't understand the destructive and constructive
interference phenomena involved with re-reflection.

Then asking a question to clarify would be in order. To me, it reads
quite ordinarily as a statement of symmetry. In my own words, it
would say that if a tank circuit can pass energy from source to load
in one direction, it can certainly perform the same transformation in
the opposite direction. After all, that is the function of
transformation and a passive circuit composed of L and C is strictly
linear. Circuit analysis allows us to treat a load as a source in the
complete circuit description.

This is the symmetry of the illustration of external signals. You
used external signals yourself as part of your case study; hence the
relevance has been made by you.

Whoa, Richard! You'll have to point out where I've discussed external signals in any case study involving
phase relationships between forward and reflected waves. I've never done so knowingly.

It seems to me that in your initial post in the original thread (that
was largely ignored for comment) you made mention of injecting a
signal from an external source into the mouth of the dragon for the
purposes of measuring the source Z. Am I wrong?

And we return to the sine non quo for the discussion: phase.

That's true, but although RF apparently realizes that the phase relationship is relevant, he doesn't seem to
understand the details of the phase requirements that achieve the necessary interferences that accomplish the
impedance matching.

That is not what I read.

It seems he is on the face of it, doesn't it? Afterall, he is quite
explicit to this in the statement you are challenging.

No Richard, I don't believe he is. I don't see the 'explicitness' you seem to find. It's the complete lack of
the explicitness that makes me believe he doesn't quite get it.

That has not been my impression of the complete post.

Nothing here contradicts anything either of you have to say.

True, but RF just hasn't said it all, because, as I said above, I don't believe he understands the details of
the phase requirements to achieve the match.

That has not been my impression of the complete post.

This phenomenon occurs in all tube transmitters in the ham world when the tank circuit is adjusted for
delivering all available power at a given drive level.

This introduces the two concepts of the "need for match" and the
"match obtained." They are related only through an action that spans
from one condition to the other. They do not describe the same
condition, otherwise no one would ever need to perform the match:

I don't comprehend your statements in the paragraph above.

The initial mismatch and its correction do not describe the same
condition. There is a first state, and then the operator imposes a
second state in reaction.

If a tree were to fall onto the antenna, a new mismatch would occur.
Would the transmitter faithfully meet the expectations of the Ham
unaware of the accident? No, reflected (0-179 degrees) energy would
undoubtedly offer a 50% chance of excitement in the shack. The
consequences of dissipation would be quite evident on that occasion.
For the other 180 (180-359) degrees of benign combination; then
perhaps not.

If a tree were to fall onto the antenna the new mismatch would surely detune the transmitter, causing unwanted
dissipation, of course, but only a lid would fail to retune the transmitter before removing the tree.

Of course, but then this is a single instance: a mismatch causing
possible increased dissipation within the source. "Possible" is in
proportion to phase relationships; dissipation is always.

If you retune to correct the mismatch's potential to destruction (or
to provide full power through-put); then you have moved to another
state or configuration. That new state admits the potential negative
consequence of the first state.

IMHO, Richard, the mfgrs of solid-state rigs with no means of matching the output to a load other than 50
ohms short changed the ham, thus requiring him to be satisfied with the power fold back, or buy an antenna
tuner.

A tube rig requires the same means of matching. It's a wash.

73's
Richard Clark, KB7QHC

Keith Dysart wrote:
Ghosting is explained by reflected voltages and currents.

Z0 has a large resistive component and a small reactive
component. Vref*Iref = Vref^2/Z0 = Iref^2*Z0 = real watts
You cannot have reflected voltages and currents that
contain zero energy. In fact, a reflected TEM wave must
have its E-field and H-field 90 degrees apart. The
watts contained in the reflected EM wave are ExB, i.e.
real watts.

In a flat-matched system the forward traveling wave is
the only one that exists. Would you also argue that
the forward traveling wave doesn't contain any energy?
All traveling waves contain energy including reflected
traveling waves.

I notice that you frequently use this example, unfortunately
never completing the analysis.
Since you leave it unspecified, let me choose the
output impedance of the TVSG to be 450 Ohms. Now there is
'reverse power' in the ladder line but no ghosts. Where did
the 'reverse power' go such that it does not produce ghosts?

Into heating the 450 ohm circulator load resistor that you
would have to install to get the generator impedance to
exhibit 450 ohms to the reflected waves. Otherwise, the
generator will exhibit a mismatch to the 450 ohm line.
It is *impossible* for the generator to see 450 ohms
when looking into a Z0=450 ohm line with reflections. So
it is impossible for the reflected wave to encounter a
V/I ratio of 450 ohms in the active generator (unless a
450 ohm circulator resistor is installed).

And since multiplying reverse voltage by reverse current does
not, in general, produce a real power, there is no power to
account for.

Suggest you review transmission line theory. If reverse
voltage and reverse current exists, the transmission
line forces their ratio to be Z0, i.e. 450 ohms, i.e. in
phase. V*I*cos(0) = watts. Since reflections are causing
ghosting, it is prima facie evidence that "real power"
is being extracted from the reflected wave.
--
73, Cecil http://www.w5dxp.com

On 23 Mar 2007 09:21:07 -0700, "Dr. Honeydew"
wrote:

Thank you, Mr. Clark. But I'm having trouble reconciling what you
wrote with what Mr. Harrison posted about the output impedance being
equal to the conjugate of the load which dissipates the most power.
Clearly the 40 ohm load dissipates more power than the 50 ohm load, so
we don't see how your answer and Mr. Harrison's posting can both be
correct.

It is a problem of apples and oranges. Your source is not
representative of either a commercial transmitter, nor a amateur
transmitter. It is a precision source. It has no need to exhibit
impedance matching, and is thus not designed to perform that purpose.
It is happy to run quite inefficiently as efficiency is a discardable
quality. Rather, it is incumbent upon you to enforce matching by
careful load selection. Otherwise, its utility is wasted and makes it
a rather expensive choice for a general purpose signal generator.

73's
Richard Clark, KB7QHC

On Mar 23, 7:18 pm, Cecil Moore wrote:
Keith Dysart wrote:
I notice that you frequently use this example, unfortunately
never completing the analysis.
Since you leave it unspecified, let me choose the
output impedance of the TVSG to be 450 Ohms. Now there is
'reverse power' in the ladder line but no ghosts. Where did
the 'reverse power' go such that it does not produce ghosts?

Into heating the 450 ohm circulator load resistor that you
would have to install to get the generator impedance to
exhibit 450 ohms to the reflected waves. Otherwise, the
generator will exhibit a mismatch to the 450 ohm line.
It is *impossible* for the generator to see 450 ohms
when looking into a Z0=450 ohm line with reflections. So
it is impossible for the reflected wave to encounter a
V/I ratio of 450 ohms in the active generator (unless a
450 ohm circulator resistor is installed).

You are trying too hard. Even your problem statement said
"no circulator". So I offer a simple example of such a
generator: a voltage source connected by a 450 Ohm resistor
to the output terminal. Voila: a generator with 450 Ohm
output impedance. Not too efficient perhaps, but the design
is used when quality source matching is desired or when
reflections need to be suppressed but it is impractical to
terminate the load in the characteristic impedance of the
line.

Now back to the problem... and the questions...

Actually, "reflected energy" rather than "reverse power".
Here is very close to an experiment we did at Texas A&M
during the 50's. We observed the ghosting and the professor
explained reflected energy waves to us.

TVSG-----1000 feet 450 ohm ladder-line---75 ohm TV RCVR

If the TV Signal Generator is not equipped with a circulator
to get rid of the reflected energy wave, ghosts will appear on
the TV RCVR. The ghosts are exactly where they should be if
reflected wave energy exists. How would you explain the
ghosting?

I notice that you frequently use this example, unfortunately
never completing the analysis.
Since you leave it unspecified, let me choose the
output impedance of the TVSG to be 450 Ohms. Now there is
'reverse power' in the ladder line but no ghosts. Where did
the 'reverse power' go such that it does not produce ghosts?

If it is re-reflected, then it is a delayed copy of the original,
i.e. a ghost. So where does it go? Seems to me there is only
two ways and the way that does not produce a ghost is into the
generator, so we need an accounting of this power within the
generator, iff it is real power.

Of course there is no issue once you let go of the notion of
'reverse power'. The reverse voltage and current pass into
the generator since the generator is matched to the line and
nothing is reflected.

And since multiplying reverse voltage by reverse current does
not, in general, produce a real power, there is no power to
account for.

Suggest you review transmission line theory. If reverse
voltage and reverse current exists, the transmission
line forces their ratio to be Z0, i.e. 450 ohms, i.e. in
phase. V*I*cos(0) = watts. Since reflections are causing
ghosting, it is prima facie evidence that "real power"
is being extracted from the reflected wave.

Oh I can do the math, and the units are definitely Watts
but that doesn't necessarily mean they offer any reality.
The toaster in my kitchen has 120 Volts on it and the lamp
is drawing 1 Amp (and the two are in phase), but that does not
mean that 120 toaster-lamp Watts has any meaning.

....Keith

Keith Dysart wrote:
You are trying too hard. Even your problem statement said
"no circulator". So I offer a simple example of such a
generator: a voltage source connected by a 450 Ohm resistor
to the output terminal. Voila: a generator with 450 Ohm
output impedance.

The generator is an *active dynamic source*. It does
not have a 450 ohm output impedance just because you
install a 450 ohm resistor. Just as soon as reflected
waves are allowed to reach the source, the source
impedance dynamically shifts away from the 450 ohm
value.
--
73, Cecil http://www.w5dxp.com

On Mar 23, 9:21 pm, Cecil Moore wrote:
Keith Dysart wrote:
You are trying too hard. Even your problem statement said
"no circulator". So I offer a simple example of such a
generator: a voltage source connected by a 450 Ohm resistor
to the output terminal. Voila: a generator with 450 Ohm
output impedance.

The generator is an *active dynamic source*. It does
not have a 450 ohm output impedance just because you
install a 450 ohm resistor. Just as soon as reflected
waves are allowed to reach the source, the source
impedance dynamically shifts away from the 450 ohm
value.

I notice that you've skipped the important question posed in
the example. I'll try again.

Use my generator: voltage source, 450 Ohm resistor to the output.
No circulator.
Drive your system: 450 Ohm line terminated with a 75 Ohm TV receiver.

TVSG-----1000 feet 450 ohm ladder-line---75 ohm TV RCVR

Ghosts or no?
If no? Where did the 'reverse power' go?

If ghosts? Well, think very carefully before choosing this option
because there aren't.

....Keith

Keith Dysart wrote:
If ghosts? Well, think very carefully before choosing this option
because there aren't.

There will be ghosting but because of the attenuation
in the 450 ohm series resistor, the ghosting will be
below the level detectable on a TV screen by the human
eye.
--
73, Cecil http://www.w5dxp.com

On Mar 23, 11:06 pm, Cecil Moore wrote:
Keith Dysart wrote:
If ghosts? Well, think very carefully before choosing this option
because there aren't.

There will be ghosting but because of the attenuation
in the 450 ohm series resistor, the ghosting will be
below the level detectable on a TV screen by the human
eye.

It would be much more convincing if you were to compute the
magnitude of the ghost rather than handwaving an answer.

Though when you do so, you will find that it is exactly zero,
so be prepared.

....Keith

"Keith Dysart" wrote in message
oups.com...
On Mar 23, 11:06 pm, Cecil Moore wrote:
Keith Dysart wrote:
If ghosts? Well, think very carefully before choosing this option
because there aren't.

There will be ghosting but because of the attenuation
in the 450 ohm series resistor, the ghosting will be
below the level detectable on a TV screen by the human
eye.

It would be much more convincing if you were to compute the
magnitude of the ghost rather than handwaving an answer.

Though when you do so, you will find that it is exactly zero,
so be prepared.

...Keith

its all ghosts and mirrors!

forget power, forget energy, they are products of other calculations. all
that is needed is impedance and voltage OR current. once you know voltage
OR current and the impedance you can calculate all the rest.