On Wed, 28 Feb 2007 03:10:28 GMT, Owen Duffy wrote:

You will note that my calculation for the 5+j0 case is less than the
Matched Line Loss, not higher.

Hi Owen,

I already anticipated that, didn't I? Certainly parsing my last
discussion is hardly necessary.

I note you have no solution that answers for the loss in a fairly
typical instance for a fairly typical line condition. It couldn't
have been any more difficult than your former computations, could it?
(In fact it is, but not conceptually.) And yet the absence of that
effort is notable (OK, so you've been ambushed). I may have stumbled
on a novelty application but I didn't trip over a boulder of a common
usage.

Given this sub-thread flowed from my response that a source does
dissipate a reverse power flow (both of which, the direction and
dissipation, are held in contention); and further given my "perverse"
challenge fully specifies such a condition and has a real solution, it
stands to reason that if your general computation is in fact general,
then it can resolve the contention to one or both of our satisfaction.
All it requires is that your math treatment accepts both directions of
power flow, and loss in the source. This is not unreasonable,
especially when any number of references encompass just such concepts.

73's
Richard Clark, KB7QHC

On Wed, 28 Feb 2007 05:05:47 GMT, Owen Duffy wrote:

If you read and understood the article, you would see that the instrument
is based on sampling the V/I ratio at a point, and that being surrounded by
transmission line is not important to the principle of operation, in other
words, it does not directly measure a reflected wave.

Hi Owen,

Can you express it without the presumption and still carry the
argument? I have read and understood many treatments on the topic,
and none claim to be the sole and unadulterated truth as it is
generally understood that many analyses work simultaneously and none
deny the validity of the others.

You have not yet actually offered any treatment that denies the bone
of contention that lies in two subject lines:
1. Reverse power is manifest;
2. The source will absorb and dissipate it.

You may have struggled with others over this in times past, but by
your own descriptions they had little intellectual horsepower, and
less experience in the matter.

I have attended schooling specific to these issues, and have practiced
professionally in their measure to the highest of standards. My peers
have instituted national metrology laboratories in your half of the
planet (OK, so it was Korea).

I have measured SWR with Bruene designs (as vulgar as that is);
Directional Couplers, Slotted Lines; and power with half a dozen
different style of sensors, and as many different methodologies. I
have also calibrated these instruments (all of them including the
vulgar Bruene designs). I can separate out the constituent waves (in
spite of the denial of their existence) by several means - each
appropriate to the problem at hand. I can measure excessively high
SWR precisely where others would shrug and simply call it infinite (it
isn't). I can also reduce residual SWR (anyone know what that is?).
I've done this over a spectrum from nearly D.C. to 12 GHz. And I get
a chuckle out of a claim for 0.014dB loss when I know full well
through experience it is unverifiable, unmeasurable, and hence
unproveable except in a spread sheet as a statistical curiosity.

73's
Richard Clark, KB7QHC

Richard Clark wrote in
:

....
I note you have no solution that answers for the loss in a fairly
typical instance for a fairly typical line condition. It couldn't
have been any more difficult than your former computations, could it?
(In fact it is, but not conceptually.) And yet the absence of that
effort is notable (OK, so you've been ambushed). I may have stumbled
on a novelty application but I didn't trip over a boulder of a common
usage.
....

Richard,

No, it is just that I have not posted a solution as yet.

Your problem was described as "Presume a source of 100+j0 Ohms impedance
sees a 50 Ohm line that is 5.35 wavelengths long and is terminated with a
load of 200+j0 Ohms. The normal attenuation of the line is 2.00 dB. What
is the loss in the line?"

Rather than sit down an write a bunch of stuff to calculate it, I took
the lazy way out and played with a scenario using Belden 8262 (RG58C/U)
in my line loss calculator that was pretty close to your scenario (Zo is
a touch different at 50-j0.24, most lines with loss will have a non-zero
jX component in Zo). My result for 15.8m of 8262 at 67MHz with a 200+j0
load is a transmission line loss (power into the load divided by power
into the line at the source end) is 3.3dB. This value of line loss is
independent of the source equivalent impedance.

If I reproduced the algorithms with the exact propagation constant and Zo
for your problem scenario, the answer would be more accurate, but I think
similar, and still obtained independently of the source impedance, and
not worth the time.

The figures from the calculator are below if someone wants to play with
it.

Now, are you prepared to post your solution?

Owen

Parameters
Transmission Line Belden 8262 (RG-58C/U)
Code B8262
Data source Belden
Frequency 67.000 MHz
Length 15.800 metres
Zload 200.00+j0.00 ?
Yload 0.005000+j0.000000 ?
Results
Zo 50.00-j0.24 ?
Velocity Factor 0.660
Length 1924.75 °, 5.347 ?
Line Loss (matched) 1.997 dB
Line Loss 3.279 dB
Efficiency 47.00%
Zin 30.48+j24.99 ?
Yin 0.019622-j0.016087 ?
VSWR(source end) 2.22
VSWR(load end) 4.00
? 1.46e-2+j2.13e+0
k1, k2 1.30e-5, 2.95e-10
Correlation coefficient (r) 0.999884

Presume a source of 100+j0 Ohms impedance sees a 50 Ohm line that is
5.35 wavelengths long and is terminated with a load of 200+j0 Ohms.
The normal attenuation of the line is 2.00 dB. What is the loss in
the line?

Can your general solution solve this? It uniquely describes both the
kinetics of reverse power flow AND the impact of source resistance.

No one has every answered this one correctly, by the way (and I can
anticipate you are ready to spring that observation on me with your
source feeding essentialy a voltage oriented high Z load as opposed to
the current oriented low Z load).



VSWR 4.75
Loss 3.55dB

73
Jeff

Richard Clark wrote in
:

....

You have not yet actually offered any treatment that denies the bone
of contention that lies in two subject lines:
1. Reverse power is manifest;
2. The source will absorb and dissipate it.

Richard, if you go back over my postings in this thread, I have not denied
either of these things.

I did comment on 2 as an explanation, one which I think is poor because of
the conclusions that might be drawn from it, eg any mismatch creates
reflected power which must be dissipated in the PA.

I did suggest that in the steady state, in a tx-line-load scenario, the
impedance looking into the line can be found, and that equivalent load
adequately explains the PA's behaviour.


You may have struggled with others over this in times past, but by
your own descriptions they had little intellectual horsepower, and
less experience in the matter.

I never said such a thing, if it is your conclusion, I disagree with it.

....

Owen

"Jeff" wrote in news:45e53c39$0$26694
:


Presume a source of 100+j0 Ohms impedance sees a 50 Ohm line that is
5.35 wavelengths long and is terminated with a load of 200+j0 Ohms.
The normal attenuation of the line is 2.00 dB. What is the loss in
the line?

Can your general solution solve this? It uniquely describes both the
kinetics of reverse power flow AND the impact of source resistance.

No one has every answered this one correctly, by the way (and I can
anticipate you are ready to spring that observation on me with your
source feeding essentialy a voltage oriented high Z load as opposed to
the current oriented low Z load).



VSWR 4.75

A 200 ohm load on a 50 ohm line is 4:1 at the load end in my view, and it
is lower as you move toward the source.

Owen

Loss 3.55dB

73
Jeff

VSWR 4.75

A 200 ohm load on a 50 ohm line is 4:1 at the load end in my view, and it
is lower as you move toward the source.


Indeed; 4:1 decreasing to 3.2:1 at the source, BUT only when the source is
50ohms.

Change the source impedance to 100ohms and the picture changes to 5.5:1 at
the load and 4.75:1 at the source end.

By the way the vswr figures will change cyclically with frequency assuming a
fixed length of coax ( 5.35 wavelengths at a fixed frequency), between about
7.5 and 2.5 at the load and 7 and 1.5 at the source.

73
Jeff

Richard Clark wrote:
On Wed, 28 Feb 2007 05:05:47 GMT, Owen Duffy wrote:


If you read and understood the article, you would see that the instrument
is based on sampling the V/I ratio at a point, and that being surrounded by
transmission line is not important to the principle of operation, in other
words, it does not directly measure a reflected wave.


Hi Owen,

Can you express it without the presumption and still carry the
argument? I have read and understood many treatments on the topic,
and none claim to be the sole and unadulterated truth as it is
generally understood that many analyses work simultaneously and none
deny the validity of the others.

You have not yet actually offered any treatment that denies the bone
of contention that lies in two subject lines:
1. Reverse power is manifest;
2. The source will absorb and dissipate it.

You may have struggled with others over this in times past, but by
your own descriptions they had little intellectual horsepower, and
less experience in the matter.

I have attended schooling specific to these issues, and have practiced
professionally in their measure to the highest of standards. My peers
have instituted national metrology laboratories in your half of the
planet (OK, so it was Korea).

I have measured SWR with Bruene designs (as vulgar as that is);
Directional Couplers, Slotted Lines; and power with half a dozen
different style of sensors, and as many different methodologies. I
have also calibrated these instruments (all of them including the
vulgar Bruene designs). I can separate out the constituent waves (in
spite of the denial of their existence) by several means - each
appropriate to the problem at hand. I can measure excessively high
SWR precisely where others would shrug and simply call it infinite (it
isn't). I can also reduce residual SWR (anyone know what that is?).
I've done this over a spectrum from nearly D.C. to 12 GHz. And I get
a chuckle out of a claim for 0.014dB loss when I know full well
through experience it is unverifiable, unmeasurable, and hence
unproveable except in a spread sheet as a statistical curiosity.

73's
Richard Clark, KB7QHC

Hi Richard,

Not that I dispute anything here necessarily, but I would like to know
how you went about measuring the reflected power dissipated within a
source. Also, how the power being dissipated?

Thanks and regards,

Jim, AC6XG

On Mon, 26 Feb 2007 20:38:00 GMT, Owen Duffy wrote:

The danger in the "power is refelected at a mismatch" explanation, is
that it follows that power reflected at a mismatched antenna flows back
toward the transmitter and is at least partially absorbed in the PA as
heat. Though that is a popular belief, it is not supported by fact.

This is the complete quote to which I responded in a recent
side-thread. You have lately expressed:

On Wed, 28 Feb 2007 08:55:24 GMT, Owen Duffy wrote:

You have not yet actually offered any treatment that denies the bone
of contention that lies in two subject lines:
1. Reverse power is manifest;
2. The source will absorb and dissipate it.

Richard, if you go back over my postings in this thread, I have not denied
either of these things.

What have I missed about "it is not supported by fact?" What do you
mean by "is a popular belief?" I am swayed by facts and I don't
really like general statements that are couched in belief systems.

73's
Richard Clark, KB7QHC

On Wed, 28 Feb 2007 08:55:24 GMT, Owen Duffy wrote:

Richard Clark wrote in
:

...

You have not yet actually offered any treatment that denies the bone
of contention that lies in two subject lines:
1. Reverse power is manifest;
2. The source will absorb and dissipate it.

Richard, if you go back over my postings in this thread, I have not denied
either of these things.

Hi Owen,

It is surprising the conclusions I've drawn from our correspondence
then. As I've steadfastly expressed nearly every posting in these
terms, you have not exactly responded to my misunderstanding in an
uniform manner.

I shall return to those postings to enquire further rather than
laboring the point here.

I did comment on 2 as an explanation, one which I think is poor because of
the conclusions that might be drawn from it, eg any mismatch creates
reflected power which must be dissipated in the PA.

This is not a denial? I see no positive characteristic you have
derived from 2 as allowing it is acceptable.

I did suggest that in the steady state, in a tx-line-load scenario, the
impedance looking into the line can be found, and that equivalent load
adequately explains the PA's behaviour.

Yes, this allowing reflected power in your terms, allowing you to
express it as a fiction suitable to providing a truth in creating the
lumped equivalent. This may have the heavy hand of my
editorialization, but it is forced by the equivocation I find in your
points I am responding to here.

You may have struggled with others over this in times past, but by
your own descriptions they had little intellectual horsepower, and
less experience in the matter.

I never said such a thing, if it is your conclusion, I disagree with it.

As I have never raised the discussion of "others" or how "they"
developed poor explanations or subscribed to faulty premises; then my
perhaps over-arching characterization is what you are rejecting as
your having said. You may note that at that time I explicitly offered
that their contributions were not germane to the facts.

73's
Richard Clark, KB7QHC