It occurs to me I might be able to do a whole lot better than actual
measurements. I should be able to simulate a power meter in the SWCadIII
Spice simulator, and do a transient analysis. This will let me go from RF to
DC out. They also have models for lossless and lossy transmission lines,
which should make it possible to see how steady state is reached from
turning the source on at T=0.

Tam/WB2TT

Hi Tam,

Yes, the lower reactance -- lower Q, and the lower frequency, will
both help keep the disturbance from the meter at a reasonable level.
If you simply re-tune the 50pF cap in Cecil's 7.2MHz 'speriment, you
still end up with about 1.2:1 SWR, because it's effectively a "T"
impedance matching network. But the same line at 1.8MHz with C and L
at 50 ohms reactance, re-tuned to resonance after insertion of the
meter, gives about 50dB return loss, and you'd be lucky to resolve
that with a typical SWR meter. Of course, you're stuck with 1.8nF of
capacitance too.

Let us know how it works out when you have time. I like your idea of
peeking inside the bridge; I had the same thought.

Cheers,
Tom

"Tarmo Tammaru" wrote in message ...
"Tom Bruhns" wrote in message
m...

(Tam: my recommendation is to do the test yourself. It will be a lot
easier to play with "what-ifs" and to check out things that don't at
first make sense if you have direct control of the experiment.)

Cheers,
Tom
Tom,

I read you, but first I have to paint the kitchen. I was going to use 50
+/& -j50. I also want to get inside the meter and look at the voltage and
current separately. It's a Kenwood, no sealed slugs. Good point about the
meter changing the reactance; 160 m might be a good place to do this, or I
might use a variable capacitor.


Tam/WB2TT

Tom,

I am making progress with the SWCad model of the power meter. The current to
voltage converter is working, which should be the hardest part. What I like
about doing it this way is that all components have 0 tolerance, and there
is nothing in the circuit that I don't put on the schematic. Unfortunately,
I won't be able to do anything the next couple of days.

Tam/WB2TT

Tom, Cecil, etc

Well, I got the SwCAD model of the SWR/power meter operating. Very
interesting. Learned a lot that I would never have thought of by just
contemplating.

Here is the circuit:

A) An opamp with a gain bandwidth of 10000 MHz that senses the current in
the line. The current to voltage gain conversion constant is 50 I.

B) Another opamp that does the RF sum of K(V + 50 I). I am calling this
output VF.

C) A third opamp that does the RF subtraction of K(V - 50 I). Gee, lets call
this VR.

D) It can be shown that SWR=(VF + VR) / (VF - VR). I love statements like
this, but it is easy enough to prove. Let I=V/RL, and plug the first two
equations into the third.

I did a calibration run at 5W with the source set to 15.811V, ZS=0. With my
K, I get VF=3.13, VR=0, PF=5W

Now for Cecil 1. ZL = 50 - j400. VF=1.62, VR=1.56, SWR=53, PF=1.33W,
PR=1.24W.

Now for Cecil 2. ZL=50-j400, BUT ZS= 0 + J400. VF=11.2, VR=10.9, SWR=73.7,
PF=64W, PR=60.6W. I am at such a high impedance here, that I suspect the 10K
sampling resistors are loading down the circuit somewhat. (I might try 100K
instead).

Note that there is absolutely nothing explicit in the circuit that has
anything to do with transmission lines. All components are perfect; there
are no stray inductances or stray capacitors.

Tam/WB2TT


"Tom Bruhns" wrote in message
m...
Hi Tam,

Yes, the lower reactance -- lower Q, and the lower frequency, will
both help keep the disturbance from the meter at a reasonable level.
If you simply re-tune the 50pF cap in Cecil's 7.2MHz 'speriment, you
still end up with about 1.2:1 SWR, because it's effectively a "T"
impedance matching network. But the same line at 1.8MHz with C and L
at 50 ohms reactance, re-tuned to resonance after insertion of the
meter, gives about 50dB return loss, and you'd be lucky to resolve
that with a typical SWR meter. Of course, you're stuck with 1.8nF of
capacitance too.

Let us know how it works out when you have time. I like your idea of
peeking inside the bridge; I had the same thought.

Cheers,
Tom

"Tarmo Tammaru" wrote in message
...
"Tom Bruhns" wrote in message
m...

(Tam: my recommendation is to do the test yourself. It will be a lot
easier to play with "what-ifs" and to check out things that don't at
first make sense if you have direct control of the experiment.)

Cheers,
Tom
Tom,

I read you, but first I have to paint the kitchen. I was going to use 50
+/& -j50. I also want to get inside the meter and look at the voltage
and
current separately. It's a Kenwood, no sealed slugs. Good point about
the
meter changing the reactance; 160 m might be a good place to do this, or
I
might use a variable capacitor.


Tam/WB2TT

Tarmo Tammaru wrote:
Now for Cecil 1. ZL = 50 - j400. VF=1.62, VR=1.56, SWR=53, PF=1.33W,
PR=1.24W.

Now for Cecil 2. ZL=50-j400, BUT ZS= 0 + J400. VF=11.2, VR=10.9, SWR=73.7,
PF=64W, PR=60.6W. I am at such a high impedance here, that I suspect the 10K
sampling resistors are loading down the circuit somewhat. (I might try 100K
instead).

Note that there is absolutely nothing explicit in the circuit that has
anything to do with transmission lines. All components are perfect; there
are no stray inductances or stray capacitors.

Chipman alludes to such a "phenomenon of resonance" in Chapter 10,
"Resonant Transmission Line Circuits". For instance, at a conjugate match
point where 100+j100 is seen looking in one direction and 100-j100 is
seen looking in the opposite direction, there seems to be a *localized*
exchange of extra energy between +j100 and -j100 that can adversely affect
the value indicated by an SWR meter placed between those two values.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Goodness, are we talking about energy moving back and forth on a
cycle-to-cycle basis? Instantaneous power? Are you saying boar hog tits
do have a use after all -- in Texas, anyway?

Roy Lewallen, W7EL

Cecil Moore wrote:

Chipman alludes to such a "phenomenon of resonance" in Chapter 10,
"Resonant Transmission Line Circuits". For instance, at a conjugate match
point where 100+j100 is seen looking in one direction and 100-j100 is
seen looking in the opposite direction, there seems to be a *localized*
exchange of extra energy between +j100 and -j100 that can adversely affect
the value indicated by an SWR meter placed between those two values.

Cecil, W5DXP wrote:
"For instance, at a conjugate match point where 100+j100 is seen looking
in one direction and 100-j100 is seen looking in the opposite direction,
there seems to be a "localized" exchange between +j100 and -j100 that
can adversely affect the value indicated by an SWR meter placed between
these values."

If we have a resonant LC circuit, there is only resistance to limit
current. If the resonant circuit is a series combination, we can place a
certain voltage of the resonant frequency across the series combination.
Voltage across either L or C can be much larger than the applied voltage
as the reactive Z`s are equal and opposite. This leaves the applied
voltage equal to (I)(R).

Some day I hope to see Chipman`s analysis. Transmission lines have
distributed inductance and capacitance. A "conjugate match point" seems
an oxymoron to me. A conjugately matched circuit demonstrates this
condition no matter where it is sliced to look in both directions.

A resonant length of transmission line with reflections will have more
loss than a similar matched line simply because the msatched line has no
opportunity to lose some of the reflected energy.

Seems to me, we correct power factor at a load to eliminate reactive
current in the power line. We are resonating the load and eliminating a
reflection from the load.

If loss from reflected power is trivial, we don`t need to worry with
matching at the load and can match at the sending end of the line to get
the power we need.

Best regards, Richard Harrison, KB5WZI

Roy Lewallen wrote:
Goodness, are we talking about energy moving back and forth on a
cycle-to-cycle basis?

We are talking about a localized energy exchange between an
inductive reactance and a capacitive reactance during a cycle -
that third term in your energy equation - and the possible effects
on an averaging RMS wattmeter.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Richard Harrison wrote:
Some day I hope to see Chipman`s analysis.

I just bought the book on half.com.

Transmission lines have
distributed inductance and capacitance. A "conjugate match point" seems
an oxymoron to me. A conjugately matched circuit demonstrates this
condition no matter where it is sliced to look in both directions.

Nope, it doesn't, Richard. A flat system is conjugately matched, i.e.
you see 50 + j0 in one direction and 50 - j0 in the other direction.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Tue, 14 Oct 2003 09:09:20 -0500, Cecil Moore
wrote:
on an averaging RMS wattmeter.

Hi Cecil,

An average, by definition, cannot resolve a difference. Pointing out
such disconnects comes of your trying to force fit all problems to the
answer found on one xeroxed page.

This, also and again, shows to go you that introducing new variables
into an old issue you cannot resolve in the first place does little
for the new or the old.

73's
Richard Clark, KB7QHC

Cecil, W5DXP wrote:
"A flat system is conjugately matched, i.e. you see 50+j0 in one
direction and 50-j0 in the other direction."

Let`s simplify Cecil`s example. 50+j0 and 50-j0 can both be expressed as
50 ohms resistive. In other words they are the same.

A matched 50-ohm transmission line under maximum power transfer
conditions also has a 50-ohm source.

Conjugate matching is equivalent to maximum power transfer.

I agree with Cecil that: "A flat system is conjugately matched, i.e. you
see 50+j0 in one direction and 50-j0 in the other direction."

No matter where you slice the transmission line you see 50 ohms
resistive (volts and amps are in-phase) looking in either direction.
Nothing amiss except the word "conjugate" is superfluous in the special
case where the system is free from reactance.

Best regards, Richard Harrison, KB5WZI

I cleaned up the circuit somewhat. The current sense resistor is now 0.1
Ohm, and the signal is sampled through voltage follower opamps. So, there is
no shunt loading of any kind. I also increased the sampling rate.

For the example where the load is 50 - j400, and source is 0, I now get an
SWR of 66.3. Adding a source impedance of +j400 gives an SWR of 69.1. Since
I am doing a transient analysis, and reading amplitudes off the waveform,
this is about as close as I can get to having the two SWR readings be the
same. PF for the second case is now 86.25W and PR is 81.02, which gives a
net power close to the desired 5.0. The absolute numbers are clearly
meaningless; only their difference has any meaning.

I also tried a less extreme termination, 50 - j100. This gave an SWR of 5.7.
Conjugate matching at the source gave me 5.8. I think it is safe to say that
source impedance does not affect SWR.

I am going to try some other stuff, The simulator is perfectly happy if ,
for instance, I drive both sides of the meter with a 1KW signal. Either at
the same, or two different frequencies.

Tam/WB2TT
"Cecil Moore" wrote in message
...
Tarmo Tammaru wrote:
Now for Cecil 1. ZL = 50 - j400. VF=1.62, VR=1.56, SWR=53, PF=1.33W,
PR=1.24W.

Now for Cecil 2. ZL=50-j400, BUT ZS= 0 + J400. VF=11.2, VR=10.9,
SWR=73.7,
PF=64W, PR=60.6W. I am at such a high impedance here, that I suspect the
10K
sampling resistors are loading down the circuit somewhat. (I might try
100K
instead).

Note that there is absolutely nothing explicit in the circuit that has
anything to do with transmission lines. All components are perfect;
there
are no stray inductances or stray capacitors.

Chipman alludes to such a "phenomenon of resonance" in Chapter 10,
"Resonant Transmission Line Circuits". For instance, at a conjugate match
point where 100+j100 is seen looking in one direction and 100-j100 is
seen looking in the opposite direction, there seems to be a *localized*
exchange of extra energy between +j100 and -j100 that can adversely affect
the value indicated by an SWR meter placed between those two values.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Tue, 14 Oct 2003 14:51:38 -0400, "Tarmo Tammaru"
wrote:
I also tried a less extreme termination, 50 - j100. This gave an SWR of 5.7.
Conjugate matching at the source gave me 5.8. I think it is safe to say that
source impedance does not affect SWR.

Hi Tam,

From the sublime to the ridiculous. The SWR of what? Where? :-)

A transmitter is loaded with two components and a meter placed between
them - woohah! Using a SWR meter inappropriately is not proof of
measuring SWR. More sense could be found in measuring the
distribution of tea leaves.

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.

But it does have its amusing moments, and I guess when all is said and
done, that counts for something.

73's
Richard Clark, KB7QHC

"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

On Tue, 14 Oct 2003 20:32:33 -0400, "Tarmo Tammaru"
wrote:

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


Hi Tam,

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

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!"

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

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 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.
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.

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). ;-)

73's
Richard Clark, KB7QHC

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

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

---------------------------------------------

Your attitude is quite correct Tam.

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.

The indicated SWR is meaningless. It is *supposed* (?) by the meter to exist
on a transmission line which does NOT exist. What does anybody ever do with
the imaginary value except argue about it on these walls and over the
air-waves.

The thing has been fooling gullible radio amaters and professionals ever
since it was invented. Sounds very technical and knowledgable though. A
good selling point. But it hardly engenders the amateur's "Self training
and education in the art of communicating by radio". It is positively
harmful.

In what year was it first introduced? I imagine it arrived very soon after
the first expensive 5 watt RF transistor came off the production line.

However, the 0-to-infinity SWR scale can easily be treated as a typing error
by dabbing on some of that white stuff.
----
Reg, G4FGQ

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.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

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?
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

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



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

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



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

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



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Richard Clark wrote:
Chapter 3. Fig. 3-1 "Complete transmission line circuits"

Been there, done that. It doesn't resemble anything you have said.

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

Been there, done that. It doesn't resemble anything you have said.

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.

No argument - simple wave reflection stuff.

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.

No argument - the superposed net total simply becomes the forward power.

This offers how the voltage variation ALONG a transmission line is
function of BOTH source Z and load Z.

Yes, my experiment seemed to support that assertion but you rejected it.
You have rejected every attempt of mine to agree with you. It appears that
your goal is complete and utter rejection by everyone on r.r.a.a before
you will achieve happiness. Good luck - you are well on your way.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Wed, 15 Oct 2003 13:43:39 -0500, Cecil Moore
wrote:

Richard Clark wrote:
Chapter 3. Fig. 3-1 "Complete transmission line circuits"

Been there, done that. It doesn't resemble anything you have said.

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

Been there, done that. It doesn't resemble anything you have said.

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.

No argument - simple wave reflection stuff.

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.

No argument - the superposed net total simply becomes the forward power.

This offers how the voltage variation ALONG a transmission line is
function of BOTH source Z and load Z.

Yes, my experiment seemed to support that assertion but you rejected it.
You have rejected every attempt of mine to agree with you. It appears that
your goal is complete and utter rejection by everyone on r.r.a.a before
you will achieve happiness. Good luck - you are well on your way.

Hi Cecil,

My goal is complete? That was demonstrated at the bench long ago.

You mistake abandonment and rejection, but you did answer my final
question. :-)

73's
Richard Clark, KB7QHC

On Wed, 15 Oct 2003 13:34:31 -0500, Cecil Moore
wrote:

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.

Hi Cecil,

The only complaint is the poor quality of such support. I would
prefer more robust coverage than the cut-and-paste variety. Clearly
you fail to even achieve a modicum of similitude to my thesis by
instead re-phrasing it in your own unnecessary elaborations that spin
off the wall into this "model" that proves you wrong (or so Tam would
have us believe). I see you offering no compelling rebuttal to him,
so the quality of effort, consistent with weak snippages from eminent
texts, is poor as I said.

If this is my biggest problem, it doesn't originate from me, but is
imposed upon me.

73's
Richard Clark, KB7QHC

Richard,

Just a few words about modeling. Yes, they built a model of a 4004 before
they made the chip. They stopped doing that somewhere around the 386.

As for my analog simulation, the simulator I am using is distributed by
Linear Technology Inc so that people can model circuits using their chips. A
lot of real world stuff is sort of simulated, where an analog signal is
digitized, and all filtering and other audio stuff is actually done in a
DSP.

If you want to see something that will really blow your mind, check out the
Harris digital AM transmitter; and no, I don't mean a transmitter for
digital audio.

Tam/WB2TT

"Cecil Moore" wrote in message
...
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
Cecil,

There are models for both lossy and non lossy transmission line. I have not
used them, so it might take some learning. I can tell you though that given
a load and transmission line, if you find the Z at the meter with an HP
vector impedance meter, and then put a lumped impedance of that same value
at the meter, you will get the same results. The meter is a crude impedance
meter.

Tam/WB2TT

Richard,

I hope you are not mixing up analog steady state signals and reflections of
pulses. The re reflection of a signal at a source depends not only on the
impedance, but also on the voltage at the source.

Tam/WB2TT
"Richard Clark" wrote in message
...

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

On Wed, 15 Oct 2003 17:18:06 -0400, "Tarmo Tammaru"
wrote:

Richard,

I hope you are not mixing up analog steady state signals and reflections of
pulses. The re reflection of a signal at a source depends not only on the
impedance, but also on the voltage at the source.

Tam/WB2TT

Hi Tam,

Found within the body of what I posted:

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.

Didn't you say you studied under Chipman? This is HIS material, not
my derivations. Again, if I were wrong, there are enough copy holders
here to correct me. That has not come to pass in lo' these several
months.

73's
Richard Clark, KB7QHC

On Wed, 15 Oct 2003 17:03:00 -0400, "Tarmo Tammaru"
wrote:

Richard,

Just a few words about modeling. Yes, they built a model of a 4004 before
they made the chip. They stopped doing that somewhere around the 386.

As for my analog simulation, the simulator I am using is distributed by
Linear Technology Inc so that people can model circuits using their chips. A
lot of real world stuff is sort of simulated, where an analog signal is
digitized, and all filtering and other audio stuff is actually done in a
DSP.

If you want to see something that will really blow your mind, check out the
Harris digital AM transmitter; and no, I don't mean a transmitter for
digital audio.

Tam/WB2TT


Hi Tam,

I've used many simulators, including Spice and Electronic Workbench.
I've also read and adhere to Robert Pease's comments, a columnist and
engineer extraordinaire who can be just as dismissive about these
tools, especially when they cloud common sense with the impression of
legitimacy through presenting a number on the basis of faulty
presumptions.

For example, there is no way you can simulate a perfect resistor
simply and confirm it at the bench. So which is more important, the
pipe dream of a virtual circuit, or the real circuit that fails to
perform as forecast? I've seen your recitation of equations. I've
seen many like them applied to precision work that falls flat on its
face when they hit the wall of reality. Basically those so-called
simulations frequently fail to attend to many matters that are
unnoticed to 1% accuracy when the equation supplies 6 places of
resolution in perfection. No such thing could ever be duplicated
without further elaboration of the model, and as evidenced by your
example (and the successive iterations), you are in jeopardy of just
such failures in this "proof" offered.

I've measured the Ohm to seven places of resolution and 6 places of
accuracy. Ohm's Law was not enough, but it did guide at every turn in
the road that found error galore. To accomplish it, it took the
understanding of the Galvanic series, temperature, expansion,
humidity, actual power dissipated, noise, drift, as a host of many
sources of error that go unnoticed and un modeled in ad-hoc
simulations. There is of course no demand for such precision to
reveal the characteristic Z of the source, that can be accomplished
far simpler and is documented by the same authorities who took such
care in measuring the Ohm. The point of the matter, and this has been
shown in Chipman, that the presumption of a matching source in the
discussion of SWR is often taken for granted, and then dismissed as a
necessity.

The proof of a simulator is found in its suite of tests that confirm
what is demonstrable. If your simulator cannot predict the loss of
real coaxial line when faced with mismatches at both ends, then it is
not simulating actual performing conditions. You did not express any
condition of source Z within your equations, when if fails from that
reason, it necessarily invalidates the simulation. You claim, and
Cecil says otherwise, that there was no line specified (making the
specification of SWR rather obscure as a model), and as the inclusion
of a line was a necessary correlative to the exhibition of source Z,
it follows that your model is two steps removed from that argument by
your own admission. So, what is this a model of? Just what do you
mean by SWR? Which model is the most perfect if they are all better
than bench measurements? What impelled the process of changing the
model when even the first one is so much better than the bench? The
80386 would have never beat an abacus with those metaphorical
questions hanging over its model.

I've seen digital transmitters. Circuit Cellar Ink has covered this
form of modulation at least half a dozen years ago or more where Don
Lancaster offered that a digital string can present (through a low
pass filter) a power curve with distortion 60dB down (simply a matter
of string length and clocking).

73's
Richard Clark, KB7QHC

originally appeared in the new subject QZH that came as a consequence
of my typing my call FTL and Agent catching it all in with the ALT
key. :-)

On Wed, 15 Oct 2003 17:18:06 -0400, "Tarmo Tammaru"
wrote:

Richard,

I hope you are not mixing up analog steady state signals and reflections of
pulses. The re reflection of a signal at a source depends not only on the
impedance, but also on the voltage at the source.

Tam/WB2TT

Hi Tam,

Found within the body of what I posted:

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.

Didn't you say you studied under Chipman? This is HIS material, not
my derivations. Again, if I were wrong, there are enough copy holders
here to correct me. That has not come to pass in lo' these several
months.

73's
Richard Clark, KB7QHC

Richard,

I went to a Bob Pease seminar a few years ago, great guy.

You are missing one of the points of the simulation. I am not trying to
market an SWR meter. I simulated it with ideal parts so that the instrument
is not affecting the reading. How are you going to measure an SWR of 65:1
with a real meter?

I did change the source impedance, and it did not change the SWR within the
limits of what I could resolve. In addition, as I told Slick a couple of
months ago, I used a real meter (Kenwood SW2000) to measure the SWR with two
different source impedances and two different load impedances, and the
source impedance made no difference.

I don't know that the Harris transmitter is the same as what was described
in Circuit Cellar. The Harris has no modulators and no linear amplifiers;
just a bank of 65 CW power modules that get switched on and off and
synthesize the desired envelope power at something like a 20 KHz rate. Sort
of a D/A converter that runs at a power level of 50 KW.