"Reg Edwards" wrote in message
...

"Steve Nosko" wrote
With a "conjugate match" the source dissipates 50% of the power and the
load
the other 50%. This can't be changed.
=============================
Without disagreeing with what you say -

A conjugate match is not relevant in the present discussion because there
is
seldom, if ever, a conjugate match between a PA and its antenna system.

The tuning-up process is NOT intended to produce such a match.

Tuning up is just the simple process of adjusting the transmitter load
resistance to be equal to its designed-for load resistance, usually an
arbitrary 50 ohms.

The internal resistance of a transmitter is NOT 50 ohms. It is not a
design
feature. It is whatever happens to appear after the designer has met a
series of other requirements. The designer himself does not know what the
internal resistance is unless, out of curiosity, he bothers to measure or
calculate it.
----
Reg, G4FGQ

Hi Reg,
This is another track, but one I've pondered, but probably shouldn't
now... And one that I believe has seen MANY words on NetNews, no? So I'll
put this out anyway and see what I get.

As we adjust the classical pi output network, I think we are starting
high and gradually lowering the load impedance seen by the tube, no? Start
with max C at the load cap and decrease it for max Po (keep in resonance
with the plate cap) I believe in the pi config. the BIG load "C" transforms
the load (50ohms) up to a "hi" Z seen by the plate. This may be wrong,
though I believe not, so will continue with the concept.
As we do this the power to the load keeps increasing up to a point. If
we keep going, the Po drops. So, we have reached the optimum Z as seen by
the tube. I think the question at this point is "why / what" is this the
"optimum" for?
I suspect the arguments are FOR and CON conjugate match.
I think it must be agreed that it is clearly the optimum for Po, no?
--
Steve N, K,9;d, c. i My email has no u's.

"Cecil Moore" wrote in message
...
Reg Edwards wrote:
The internal resistance of a transmitter is NOT 50 ohms. It is not a
design
feature. It is whatever happens to appear after the designer has met a
series of other requirements. The designer himself does not know what
the
internal resistance is unless, out of curiosity, he bothers to measure
or
calculate it.

Proving that, like 50/60 Hz AC power, efficiency may be
more important than maximum power transfer. ...
73, Cecil, W5DXP

That's also where I was going with my "raise the plate voltage" concept.
--
Steve N, K,9;d, c. i My email has no u's.

I'll never go there in the RF arena even though another hobby of mine is
laser light shows.
Placing "photon" and "RF" in the same paragraph is ... what shall I call it,
flame-fodder?



"Richard Clark" wrote in message
...
On Wed, 25 Feb 2004 14:46:42 -0600, "Steve Nosko"
wrote:
I think the phrase "available energy" may draw discussion, but won't
start
it.
Uh-Oh
I suspect it is not the thing to focus on. However...
This has in the past lead to a cataract of 600 posting threads

With a "conjugate match" the source dissipates 50% of the power and the
load
the other 50%. This can't be changed.
This is the 1mm fuse that starts that torrent. Once lit, no one
escapes.
...
Snake oil? The math is correct, but there may be some practical limit
not
considered.

Hi Steve,

Practical or otherwise will be dismissed to the discussion of photons
and general relativity by the end of two days, if this doesn't fall
flat on its face with mine being the only comment. ;-)

73's
Richard Clark, KB7QHC

"Richard Clark" wrote in message
...
On Wed, 25 Feb 2004 12:22:32 -0600, "Steve Nosko"
wrote:

[...] you simply measure the caloric result and ignore
shape altogether.

I always thought that the common method of measuring RF power was
pretty
cool! The Thermistor or bolometer. Here you balance a bridge with DC or
low freq AC. It heats the thermistor to the correct resistance. Then,

Yea... Then I give only a partial description since trying to give
it completely would take pages, I decided to "overview" it.

However...


... and wholly absent from
amateur activities.

OOPS! "wholly"?? I've got one. A really nice (but un temp
compensated) thermistor mount) (but don't tell anyone that I have nothing
to drive it with -- the rest of the bridge.)

So here I must make a slight correction of your
description. Power meters contain two (2) such devices which form the
balanced halves of a bridge.

I gotta go back & look, (this was from the 60's) but there are two and
they are in series for the low freq and parallel for the RF. On the low
freq side it is a 200ohm mount. Now I hafta' remember how the RF was
handled .... musta' been to only one...let me think about this...


One side is exposed to the RF, the other
side is exposed to the simpler DC or AC power that is known to a high
degree of accuracy. What you describe is the detector implementation
of the same devices (which exhibit non-linearity to perform
detection). They would, in the fashion you describe, offer good
"relative" power indication, but not absolute power (except through
substitution methods).

OOPS again! You DO get absolute because you know how much low freq
power you remove. Isn't that the principle of the HP437 & 438's? or are
they doing something else...diode ... er...uh crystal if you're across the p
ond? I always thought they were, caloric, as you say.

--
Steve N, K,9;d, c. i My email has no u's.


As such, they are fairly common in precision
VSWR instrumentation especially when they are driven by 1KHz modulated
power sources, and in turn drive special AC VTVM's scaled to present
dB and VSWR to very high resolution.

A list of the methods:
The Crystal: 1N21/23/25/26...
The Bolometer (low power caloric)
The Barretter (a Bolometer): Sperry 821, PRD 630A
The Wollaston wire (a Barretter): actually a 0.01A glass fuse
The Carbon filament (a Barretter)
The Thermistor (a Bolometer): Western Electric 28A
The Thermocouple
The Thermopile (lotsa Thermocouples)

73's
Richard Clark, KB7QHC

Consider me burned out too, but I did change the subject line to allign
w/the change in topic.
--
Steve N, K,9;d, c. i My email has no u's.
"aunwin" wrote in message
news:zmq%b.127262$jk2.539846@attbi_s53...
Steve, have we now moved to an antenna that has a preamplifier on it for
listening ? If so I need not continue to struggle to follow the thread
day
by day to determine its implications to the subject at hand.
The half power thingy I presume is understood by all so IS something very
exciting to be revealed that shows that the dipole is really an efficient
radiator after all, but only if you put a class C amplifier on it ? There
are stacks of information in books and lots of words in a dictionary, but
sooner or later one has to give a reason as to why they are reading out
loud
if it is meant to be instructive or explanaatory with respect to the
thread,
i.e. dipole and its impedance. You can start a different thread which
would
help out for when one checks out the archives unless the intent
is meant to be destructive
Regards
Art


. "Steve Nosko" wrote in message
...
Hi Richard...

"Richard Harrison" wrote in message
...
[...]
"----Second, it is the RMS current through the tube which will waste
power, so that is what we must be concerned with."

I don`t believe current through a Class C amplifier consists of an
ordinary sine wave.

And I didn't say that it does nor do I believe it does. I'm
inclined
to
take my 100MHz storage scope to to the 6146's of my TS830s and see for
myself.
Your words imply (at least I infer) you are thinking that only a sine
wave has an RMS value. Every wave of any shape has an effective or RMS
value - its heating or "power causing" value.


[...] I think it consists of short unidirectional pulses.
The tuned "tank circuit" is the source of sine waves.

This certainly has to be correct. The tank will most likely cause
some
sine-like VOLTAGE waveform, but the tube current has to be pulses of
some
shape. This is a very timely discussion in view of the AC power meter
QST
article and the extensive investigation I just completed on several
pulse
shapes..


RMS is the effective value, not the average value, of an a-c ampere.

I will differ here. The RMS value is more appropriately described
as
the power producing value of ANY wave form. Pulses can produce heat
just
as
well as sine wave AC. We all know this from a practical view since
tubes
can only conduct in one direction and the plates DO get hot.



...as the heating
value of an ampere is proportional to the current squared.

This is actually a simplification. P=ExI Power is the product of
voltage and current *only*. Because this is a second order effect, in a
resistance it can be related to either voltage squared or current
squared...
because that captures the second order character. Maybe there's a better
way
to say it mathematically, but I don't know it.
When we get to non sine shapes, then we have to fall back on the
actual
definition. root [avg of square] ...with the integral and all.
http://www.ultracad.com/rms.pdf

[...snip...]

Ordinarily, with nonsinusoidal currents, the ratio of maximum to
effective value is not the square root of 2.
Best regards, Richard Harrison, KB5WZI

Doing the math for pulses with the shape of sine, triangle (a single
slope with sudden end) and trapezoid (a sudden start to one level then a
slope to a peak and a sudden end), I decided to look at the RMS to
AVERAGE
ratio since average is what a common meter will measure in Bob Shrader's
article (AC watt meter Jan 04 QST).
I was particularly interested in the sine-shaped pulses of various
duty
cycle because the current of common power supplies occurs in short
pulses
with a sine-like shape that are near the peak of the voltage waveform.
It was interesting that for all these shapes, this ratio was very
similar. One relatively simple thing to understand which came out of
the
analysis was that the average value is directly proportional to the duty
cycle as you might reasonably postulate. Where duty cycle is the ratio
of
"on" time to off time. Where "on" time is the time that ANY current
flows.
Whereas the RMS is proportional to the Square root of the duty cycle.
e.g.
drop the duty cycle to half and the RMS drops to .707.

I have to do some verification, but it sure looks as though Bob's
numbers can be as much as three times what he quoted, depending on the
waveshape and some measurements I made.

http://www.irf.com/technical-info/an949/append.htm
Trapezoid=rectangular. Also for the phase controlled sine, the things
that
look like tau and a small n are both pi i.e. sin [pi x (1-D)] cos [pi x
(1-D)] and denominator of 2 x pi


Some average & RMS values here.
http://home.san.rr.com/nessengr/techdata/rms/rms.html

More (better) average formulas:
http://www.st.com/stonline/books/pdf/docs/3715.pdf
NOW I know where the average value of a sine wave comes from =
(2/pi)
The Greek delta = d.

A calculator for RMS:
http://www.geocities.com/CapeCanaveral/Lab/9643/rms.htm

There you go again wandering off and bull****ting about something that you
read some where and no body else knows it.
If you think as you say that all has been said that needs to be said about
antennas then open another thread where you can deposite your volumous
verbal diarrea. The subject was antennas and impedance but you seem to think
that every thing is known so you can turn to any book on any subject and
empty yourself on us as if you are on a bathroom stool which is your county
seat. Now if you want to attack me regarding my antenna then fine start a
thread and we will go at it but remember it is not in a book so you will
have to think for yourself or resort to reading any old book and
regurgitating. Now you could find something about say loop antennas that you
are sure nobody else knows about or are we not upto that part in Krause's
book that you are currently reading ?
And while we are at it, now you are getting absent minded please put a
marker in the book where you left off. And another thing I will echo what
Cecil says to the like of you....an antenna is an antenna and not to be
regarded as a system. My antenna does not cry out aloud that it has had its
amplifier stolen. Another point..you mention "we" since when do you think
you talk for everyone here, only a few days ago your excuse was that you was
not a professor,! Today you screwed up with dimension units that you copied
incorrectly from YOUR book and frankly you have to post more than others
because people do not agree with you most of the time as you seem unable to
stay on target and get confused
about what the subject is or how to interpret something that you read and
screw around trying to find a way to make it relavent.
If you remembered what ever you learned in school you would be able to talk
for yourself and then debate for yourself now that Terman is dead, really
dead . Now you also said something about what I said on this thread
regarding current or something ( I think I said 'I believe' which is a long
way from acting as a know all tho I must admit I haven't been up lots of
towers,put them up in lots of countries and all those other stories that you
tell ) to which you replied bull**** or balloney which from you should be
enough so that you can walk away like a messiah you doesn't have to explain
himself based on some fabulous light around his head that he thinks he has
earned thru his fabulous teachings.
Another thing are you the only one that was correct on Reggies
question.....no I didn't see a response in the early days that I read that
thread... probably you knew all along as you read something like it in a
book so dumped that on the thread anyway.
Now if you want to change the heading of this thread then be my guest since
you and you alone knows everything there is to know about antennas as you
read this book on a tower in Del Fuego or was it in the bathroom?
This is not a personal attack by the way
it is just a disagreement like saying baloney or bull****, justification is
not required. I am sure you can identify with that
with you not being a professor and thus allowed to spout off.
Art
Looking forward to hearing you hit my antenna and the mathematics that go
with it regarding the amplifier hidden in the elements. Last time you said '
it' breaks all the laws of physics, the laws that you read in a book
somewhere and that was sight unseen, the antenna that is, the laws were
chiselled in a rock , graphical form that you saw the last time you climbed
a mountain where a bush once burned and you became a prophet


"Richard Harrison" wrote in message
...
Art, KB9MZ wrote:
"The half power thingy I presume is understood by all so IS something
very exciting to be revealed that shows that the dipole is really an
efficient radiator after all, but only if you put a class C amplifier on
it?"

Art was the introducer of efficiency into this impedance thread.
Something from Art about radiation per unit length of an antenna, if I
recall. We noted that the antenna itself is usually so efficient there`s
not much to talk about, but there are differences in the effectiveness
of getting a signal on and off the air via an antenna. There`s coupling
the antenna to the radio. This has been argued here since before the "47
KW CB" thread, and that was years ago.

If Art can get more signal out of an antenna which is as small or
smaller than ordinary without putting more current into that antenna,
assuming orientation, polarization, and the other usual conditions are
fair for the competition, I`m excited.

Best regards, Richard Harrison, KB5WZI

No I can't remember ever putting a finger/s up at anybody.
But I have this feeling that this thread is now long enough and has included
so many subjects of discussion that we have the beginnings of a full scale
augument again. However if it means that this is the time a certain person
leaves the group in discussed
then no harm done. Forget antennas and impedance and the subject change you
are advocating, let the row start now, say something,
anything so we get a repeat of the last one. Can't you say balonney or
bull**** at the next guru and tell something different to another guru and
blame it on the first guru? Throw a fishing pole with a carrot on it!
Art
Art

Art
"Cecil Moore" wrote in message
...
aunwin wrote:
Can't we assume that a antenna is a closed series
circuit containing only passive items ?

A passive antenna, when it is receiving a signal, is a pretty good
approximation to a Thevenin Equivalent circuit. The received
signal is the generator. The generator impedance is the radiation
resistance (and the lossy R's). We've got a transmission line and
usually a 50 ohm load in the receiver.

If you have in mind that we must we consider an antena as a Class
something or other amplifier when determining its impedance then I am
hopelessly lost in a thread that can only end up nasty like some others
did

Why not, for the purposes of limiting the discussion, consider only
a Thevenin Equivalent 50 ohm source for the transmitter? That way,
the entire system will be linear and easy to discuss.

I am not pointing the finger at you Cecil, ...

If you were, which one would it be? :-)
--
73, Cecil, W5DXP

On Thu, 26 Feb 2004 15:20:06 -0600, "Steve Nosko"
wrote:
OOPS again! You DO get absolute because you know how much low freq
power you remove. Isn't that the principle of the HP437 & 438's? or are
they doing something else...diode ... er...uh crystal if you're across the p
ond? I always thought they were, caloric, as you say.

Hi Steve,

They are Bolos (caloric) using PRD type elements. From your
description (barring the equipment name), it sounded like the typical
detector application. I can see you originally described a self
balancing bridge:

The HP bridge is powered three ways. It has a DC source to offer
temperature compensation and range changes (zero setting). It has an
AC Oscillator (~10 KHz) source in quadrature (topographically
orthogonal, across the bridge instead of over it). Basically, the
bridge temperature components (the Bolometer) act as an oscillator
level stabilizing feedback loop (much like the famous HP 200 which
used a lamp's negative resistance). The third power input is the
unknown RF which unbalances the heat causing the feedback to
re-regulate where the drive level changes (which is monitored by the
meter as the indication of the RF power applied).

The sum of the operation was that the bridge always operates at null
with the same heat burden for any applied RF power (within constraints
of course).

And yes, they are characterized as 200 Ohm mounts.

73's
Richard Clark, KB7QHC

On Wed, 25 Feb 2004 14:46:42 -0600, "Steve Nosko"
wrote:

snip....
With a "conjugate match" the source dissipates 50% of the power and the load
the other 50%. This can't be changed. Draw the schematic to see. Rs = RL
therefore Ps = PL. (I'll use a big "L" so it looks like an "L")

Dear Steve,

You may find the information in this article to be of interest
relative to the efficiency in a conjugate match situation.

http://www.qsl.net/w9dmk/ObservationsOnMPTT.htm

73,

Bob

I just get an advertisement when I click on your link. Mac N8TT

--
J. Mc Laughlin - Michigan USA

"Robert Lay W9DMK" wrote in message
...
On Wed, 25 Feb 2004 14:46:42 -0600, "Steve Nosko"
wrote:

snip....

Dear Steve,

You may find the information in this article to be of interest
relative to the efficiency in a conjugate match situation.

http://www.qsl.net/w9dmk/ObservationsOnMPTT.htm

73,

Bob