Cecil wrote,

Ever measure the forward and reflected currents halfway into a
shorted 1/4WL stub? How can currents be flowing unimpeded into
and out of an infinite impedance?


In the case of a lossless, 1/4WL stub, (no such thing, except on this
newsgroup) in the steady state you can disconnect the transmitter and
the currents will still be there. Current doesn't flow, Cecil, charge flows.
Current is just the rate of flow of charge, dQ/dt. In a 1/4WL stub, charge,
and the fields associated with it, are in a state of oscillation. Over time,
their average movement in space is zero. It's too bad you have to think of
current
as like the water in a big river that has to flow from one place to another
in order to exist. (That's wrong, too. Current in a river is the rate of flow
of
water past a point, not the water itself.) Sloppy semantics sure screw up
understanding.
73,
Tom Donaly, KA6RUH

Good points, my 30S-1 has load and tune still in it and the final a
3CX1500B is ceramic and can't be seen but it never lost it's Eimac stencil.
However my Collins 30L-1 was a different story. Once or twice I had 811As
with holes melted in their plate structure. They continued to work well and
I always thought this was from overdriving but now I'm not so sure because
it ran at the same high swr as the 30S-1. I used the 30L-1 in summer
because the air conditioner couldn't keep up with the heat generated by the
30S-1 so it was my winter amp.
I notice that Walt Maxwell's Reflections II was published by World Radio
whereas Reflections was by the ARRL. There is some disagreement on
"conjugate match' and probably other things between ARRL and Walt. So now I
have to wonder if the final tube is dissipative or non-dissipative for
reflections.

Looks like my new thread isn't working but I'm posting this to it just in
case since I don't really know the customary protocol on a long thread that
sometime digresses.

--
73
Hank WD5JFR
"Richard Clark" wrote in message
news
On Tue, 25 May 2004 16:12:05 GMT, "Henry Kolesnik"
wrote:
Before it came down my 20 meter antenna had a SWR approaching 20:1 and I
was
running a Collins 30S-1 and no tuner!. I did that for several years and
would be still doing if the roofers hadn't destroyed ~130 ft. dipole.
One
of these days after my back improves I'll put another one up.

Hi Hank,

I used to teach this Collins equipment in the Navy. I presume yours
had a finals tuning circuit still in it? Hard to imagine it
otherwise.

Tubes are different from transistors only by approaching the Source Z
with an inverted ratio of transformation. Ever hear of plate
resistance? It is literal resistance. Ever see a plate glow when
under the stress of hi SWR? It is literal heat. The same heat is
generated irrespective of it being explained by wave mechanics or
lumped equivalent circuits. Choose the model you are comfortable
with, and then tackle the SWR if you care about efficiency.

If anything, tube sets prove the problem of reflected power through
your ability to directly observe the heat generated and experience the
cost of new finals tubes through their degraded life span. This stuff
is all rote teaching; and my students were given practical tests to
troubleshoot, tune, and repair against such scenarios.

I've had hands-on experience with this topic both academically and at
several benches - the sophistries that deny these points are amusing,
but remain amateur scribblings.

73's
Richard Clark, KB7QHC

Tdonaly wrote:
In the case of a lossless, 1/4WL stub, (no such thing, except on this
newsgroup) in the steady state you can disconnect the transmitter and
the currents will still be there.

Since that configuration doesn't exist in reality, only God
can cause what you are asserting. Why am I not surprised that
you need a supernatural being to prove your arguments?

Current doesn't flow, Cecil, charge flows.

:-) :-) Having to resort to trivial arguments is the sure sign
of a loser. :-) :-)
--
73, Cecil http://www.qsl.net/w5dxp



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On Tue, 25 May 2004 19:43:42 GMT, "Henry Kolesnik"
wrote:

Good points, my 30S-1 has load and tune still in it and the final a
3CX1500B is ceramic and can't be seen but it never lost it's Eimac stencil.
However my Collins 30L-1 was a different story. Once or twice I had 811As
with holes melted in their plate structure. They continued to work well and
I always thought this was from overdriving but now I'm not so sure because
it ran at the same high swr as the 30S-1. I used the 30L-1 in summer
because the air conditioner couldn't keep up with the heat generated by the
30S-1 so it was my winter amp.
I notice that Walt Maxwell's Reflections II was published by World Radio
whereas Reflections was by the ARRL. There is some disagreement on
"conjugate match' and probably other things between ARRL and Walt. So now I
have to wonder if the final tube is dissipative or non-dissipative for
reflections.

Looks like my new thread isn't working but I'm posting this to it just in
case since I don't really know the customary protocol on a long thread that
sometime digresses.


Hi Hank,

Those pinholes (or larger) that you found in the plates occurred by a
very fascinating display of plasma. If you are really putting the
hurts to it, you will observe a football shaped plasma between the
plate and the cathode where the point terminates (and penetrates) in
the enlarging ruby glow of the plate. This is visible in some tubes,
not others, depending of course on tube structure. I've had students
point out tubes still operating with the glass envelope completely
melted (or jelled rather) and collapsed, hugging the structure!

Hence you have confirmed the dissipation of return power directly -
all mumbling aside from theorists who describe it as virtual. ;-)

As for Walt's publishing house shift, I don't recall him having any
technical issue, but I let that go as he found another outlet and got
to say what he considered was important. I proofed a number of his
appendices and we corresponded quite often about our differences. To
his credit, although I dispute his stand, he maintains an open mind on
the subject and offers he will look into my experiments that reveal
this. He has already measured the value of 50 Ohms, the point of
departure between us is whether this same value absorbs power.

So, you see, you get numbers from those that sit down to the bench and
do it, you get pixie dust from the rest.

And as for new thread or old, this topic has run to 600+ postings in
years past; so opening it as a new topic is fine to allow news readers
(like mine) from pushing the indentations out to the event horizon.
This post is not so deeply nested though.

73's
Richard Clark, KB7QHC

The30L-1 811A holes were dime size and I wish I knew then what I know now
because I would have made some comparisons. I would have set the drive to
get the tubes red hot on my antenna with SWR 20 and then using same drive
and Ip see what happened loading into a 50 ohm dummy and running. Perhaps
someone has done this and can report the results.
tnx

--
73
Hank WD5JFR
"Richard Clark" wrote in message
...
On Tue, 25 May 2004 19:43:42 GMT, "Henry Kolesnik"
wrote:

Good points, my 30S-1 has load and tune still in it and the final a
3CX1500B is ceramic and can't be seen but it never lost it's Eimac
stencil.
However my Collins 30L-1 was a different story. Once or twice I had
811As
with holes melted in their plate structure. They continued to work well
and
I always thought this was from overdriving but now I'm not so sure
because
it ran at the same high swr as the 30S-1. I used the 30L-1 in summer
because the air conditioner couldn't keep up with the heat generated by
the
30S-1 so it was my winter amp.
I notice that Walt Maxwell's Reflections II was published by World Radio
whereas Reflections was by the ARRL. There is some disagreement on
"conjugate match' and probably other things between ARRL and Walt. So
now I
have to wonder if the final tube is dissipative or non-dissipative for
reflections.

Looks like my new thread isn't working but I'm posting this to it just in
case since I don't really know the customary protocol on a long thread
that
sometime digresses.


Hi Hank,

Those pinholes (or larger) that you found in the plates occurred by a
very fascinating display of plasma. If you are really putting the
hurts to it, you will observe a football shaped plasma between the
plate and the cathode where the point terminates (and penetrates) in
the enlarging ruby glow of the plate. This is visible in some tubes,
not others, depending of course on tube structure. I've had students
point out tubes still operating with the glass envelope completely
melted (or jelled rather) and collapsed, hugging the structure!

Hence you have confirmed the dissipation of return power directly -
all mumbling aside from theorists who describe it as virtual. ;-)

As for Walt's publishing house shift, I don't recall him having any
technical issue, but I let that go as he found another outlet and got
to say what he considered was important. I proofed a number of his
appendices and we corresponded quite often about our differences. To
his credit, although I dispute his stand, he maintains an open mind on
the subject and offers he will look into my experiments that reveal
this. He has already measured the value of 50 Ohms, the point of
departure between us is whether this same value absorbs power.

So, you see, you get numbers from those that sit down to the bench and
do it, you get pixie dust from the rest.

And as for new thread or old, this topic has run to 600+ postings in
years past; so opening it as a new topic is fine to allow news readers
(like mine) from pushing the indentations out to the event horizon.
This post is not so deeply nested though.

73's
Richard Clark, KB7QHC

On Tue, 25 May 2004 22:32:47 GMT, "Henry Kolesnik"
wrote:

The30L-1 811A holes were dime size and I wish I knew then what I know now
because I would have made some comparisons. I would have set the drive to
get the tubes red hot on my antenna with SWR 20 and then using same drive
and Ip see what happened loading into a 50 ohm dummy and running. Perhaps
someone has done this and can report the results.
tnx


Hi Hank,

A little follow-on, if you will. I presume you tuned into the load
first before switching to the antenna. How did you determine the SWR?
Were you driving a twin lead transmission line going to your
mismatched antenna, or a coax?

73's
Richard Clark, KB7QHC

Ed Price wrote:
By definition, reflected energy dissipated in the source was never
generated in the first place.
--
73, Cecil http://www.qsl.net/w5dxp

That's not a very good definition.
Would you say that a rock, thrown vertically, never was thrown just because
it returned to hit you on the head?

Ed
wb6wsn

Electromagnetic waves can cancel, but rocks can't. Could that maybe
make a difference?

73, Jim AC6XG

On Tue, 25 May 2004 16:43:37 -0700, Jim Kelley
wrote:

Would you say that a rock, thrown vertically, never was thrown just because
it returned to hit you on the head?

Ed
wb6wsn

Electromagnetic waves can cancel, but rocks can't. Could that maybe
make a difference?

Hi Jim,

This is like mistaking electrons and charge displacement. Sound like
Ed described two rocks hitting with an inelastic collision which
results in power dissipation.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Tue, 25 May 2004 07:27:03 -0500, "Richard Fry"
wrote:

REALITY CHECK: If tx source Z really was 50 ohms, a tx connected to a 50
ohm load would lose 1/2 of the RF power it generates to that internal Z.


Dear Richard,

This is the time-honored misreading and misapplication of Thevenin's
theorem posed by Edison to confound investors in Westinghouse's AC
generation plants. Look at the ratio of DC to AC power plants
constructed in the past century to find the poor accuracy of your
reading.

73's
Richard Clark, KB7QHC

Boy, I'm gonna have to try and find my old EE5xx Non-Linear Transistor
Design notebook. I doubt I could translate it into words for this
section of the thread, but it is incredibly applicable.

I took it not knowing what it really was - RF amplifiers, tank circuits
and matching circuits of every flavor, and how much DC power was used
and RF delivered at the primary freq and all harmonics. He also covered
doublers, triplers, phase locked loops (from scratch), the whole 9
yards. I learned more in that one class than in any other 5 I took.
The professor was fantastic and very very tough. It was also the most
demanding course I ever took.

tom
K0TAR

I used 450 ohm ladder line and a balun along with a cheap SWR meter.

--
73
Hank WD5JFR
"Richard Clark" wrote in message
...
On Tue, 25 May 2004 22:32:47 GMT, "Henry Kolesnik"
wrote:

The30L-1 811A holes were dime size and I wish I knew then what I know
now
because I would have made some comparisons. I would have set the drive
to
get the tubes red hot on my antenna with SWR 20 and then using same
drive
and Ip see what happened loading into a 50 ohm dummy and running.
Perhaps
someone has done this and can report the results.
tnx


Hi Hank,

A little follow-on, if you will. I presume you tuned into the load
first before switching to the antenna. How did you determine the SWR?
Were you driving a twin lead transmission line going to your
mismatched antenna, or a coax?

73's
Richard Clark, KB7QHC