On Tue, 27 Sep 2005 17:29:10 +0000 (UTC), "Reg Edwards"
wrote:

If's and But's are not required.
The antenna is just an arbitrary load.
Does the meter reading indicate SWR on the feedline (which is what is
usually required), or does it not?
This is not a "catch question". It is not a troll.
No, of course it isn't (must be all those other posts then)
"Antenna or Feedline?" please.
KISS

Hi Reggie,

Ah yes! That "additional information" finally surfaces as a
requirement doesn't it?

SWR "on the feedline" is like dust thrown into the eyes of the rubes
before the elephant appears in front of them. Presumably, "on the
feedline" is akin to the ark holding a sacred artifact like the finger
of St. Heavybottom.

The traditional slotted line used for probe determination of SWR comes
with two connectors like that commonplace SWR meter (and the slotted
line probe connects to a - SWR METER! albeit, not the commonplace
variety, but odd how the tide of time has not yet altered the name to
TLI). And if we were to substitute the slotted line for commonplace
SWR (or t'other way 'round), both/either/each would face the same
issues and offer the same results. Imagine that, not a whit of
difference, except that the probes can add error through in-expert
use. Whoops! Same issues of how things can/do go wrong.

So, the ultimate question of the universe (yadda-yadda-yadda) is what
difference does having a transmission line between these two
connectors make on the outcome of what SWR exists AT the load
connector? A rhetorical difference! After-all, you would need
"extraordinarily more information" to express where the SWR resided,
wouldn't you? ;-)

Any artificial constraint you toss in as an objection exists for
yourself as well. I can see Kelvinator swinging his cane now. Did I
say lower 6th? They would probably hoot you down to upper 5th.

73's
Richard Clark, KB7QHC

"Reg Edwards"

"Antenna or Feedline?" please.
KISS
___________

Antenna.

And a big smooch to you, too.

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

Rich, thanks for the smooch.

But I'm afraid you are wrong. The meter correctly indicates SWR on
the feedline when it is located at the antenna end of the line.

But don't worry too much about it. It seems you are in good company.
So much for the technical education of radio engineers.

It all comes about because of so-called SWR meters being called SWR
meters - which they are not. At least not when located at the
transmitter end of transmission lines as they nearly always are.

When located adjacent to the transmitter they are TLI's. Transmitter
Loading Indicators. And SWR has very little or nothing to do with it.
----
Reg.

Cec, you can make the meter read anything you like just by twiddling
the calibration pot. Of what bloody use is that? !**?!!

Just answer the obvious question. No If's or But's
----
Reg.


"Cecil Moore" wrote in message
...
Reg Edwards wrote:
"Antenna or Feedline?" please.

Rich, your abuse of the English language renders it impossible for me
or anybody else to make any sense of what you are waffling about.
----
Punchinello, G4FGQ

On Tue, 27 Sep 2005 19:13:16 +0000 (UTC), "Reg Edwards"
wrote:

Rich, your abuse of the English language renders it impossible for me
or anybody else to make any sense of what you are waffling about.

Aw Reggie,

Are you using a prescription grade wine glass when you were trying to
read it? Or can we blame it on the grape? No ifs ands or buts now
because with each new post the question becomes more remote and harder
for you to answer.

73's
Richard Clark, KB7QHC

Reg Edawds, G4FGQ wrote:
"R&B`s cavity magnetron was developed at Birmingham University in the
midst of the air raids on that industrial city."

Prior to Randall & Boot, magnetrons were low-power devices, outclassed
ny klystrons. R & B`s resonant-cavity magnetron, operating at 10 cm
exuded 100x more power than previous magnetrons and allowed smaller
hardware and imptoved image definition.. The 6 KW GEC manufactured
version given to the U.S. in August 1940 was shipped by ordinary parcel
post to arouse no suspicion of its importance. It has been called the
most important shipment ever to arrive on U.S. shores.

The resonant-cavity magnetron was an awesome contribution to victory in
WW-2 against both Germany and Japan. Their radar development lagged far
behind.

My ship in WW-2 had only one spare part kept in the captain`s safe, the
Raytheon resonant-cavity magnetron for our Raytheon navigational radar
system. Fortunately, we never needed to replace it.

After WW-2, Rayrheon shifted production to their bew "Radar Range". The
Japanese soon caught up with their ubiquitous microwave ovens. They were
more motivated. Our houses were already equipped with oil, gas, and
electric ranges aplenty. Everyone, it turned out, was ready for
microwave too.

Klystrons were not washed up either. The most powerful generators ever
built were klystrons. The speed detector used to ticket your car
probably uses a laser. All radar isn`t pulsed radar. Radar altometers
use separate transmitter and receiver antennas. They transmit an FM
signal whose modulation frequency is changing at a certain rate. This is
continuously compared with the modulation frequency of the received echo
to tell how far away the reflection point is.

The television signal you watch off the air was probably generated by a
large klystron.

Best regards, Richard Harrison, KB5WZI

"Reg Edwards"
But I'm afraid you are wrong. The meter correctly indicates
SWR on the feedline when it is located at the antenna end
of the line.
______________

Remove the feedline, and connect the 100 ohm antenna through the SWR meter
calibrated for 50 ohms, directly to the transmitter. The meter has a
reading. The measurement will have the same value as before, neglecting any
adjustment for having no line loss now. But there is no feedline, so how
can there be any SWR on it, you write.

The fact that there is not enough transmission line length in the system for
literal standing wave maxima and minima to develop on it does not mean that
reflections do not exist in the output load system. It is the value of
those reflections that determines the corresponding value of SWR.
Reflections can be measured by appropriate instruments regardless of the
length of line in the measured system, or even the existence of any
transmission line at all.

The convention of the professional engineering community for many decades
has been to convert incident and reflected waveform samples into the
corresponding value of SWR, no matter if there is insufficient line length
in the system for the corresponding maxima and minima to develop fully on
it. It doesn't matter, electrically. Your constant diatribes stating that
it does is a futile exercise.

Disable the SWR protection in your ham tx and key it to full power into an
open or short. There is no transmission line where standing wave maxima and
minima could exist, but your tx will burn up anyway.

Maybe save your response until tomorrow morning, when your Merlot buzz has
worn off

RF

Teg, G4FGQ wrote:
"Err, no, the meter is telling what it sees at the point of
measurement."

Yes, and that is a ratio depending on "rho", the reflection coefficient.

We know that rho equals:

the square root of reflected pwr / fwd pwr

And: VSWR = 1+rho / 1-rho

VSWR is a function of the reflection coefficient

You drive an automobile and glance at the speedometer. It is an
electrical meter giving an indication proportional to vehicle speed.

You look at an SWR (TLI) meter giving an indication calibrated to be
proportional to SWR.

Best regards, Richard Harrison, KB5WZI

"Reg Edwards"
But I'm afraid you are wrong. The meter correctly indicates
SWR on the feedline when it is located at the antenna end
of the line.
______________

PS:

In this example the mismatch between the antenna and the line is the source
of the reflection that results in system SWR. Convention is to state that
the SWR belongs to the antenna, not the line -- although the added stress on
components applies only to the line and tx, and not to the antenna.

An ideal SWR meter will read that antenna reflection to have the same value
when installed at either end of the line, or anywhere along its length
(assuming
a perfect 50 ohm line, and neglecting line loss).

RF

Reg Edwards wrote:
Jim, I'm sorry you are unable to answer the simple question "Feedline
or Antenna?".
----
Reg.

It appears you have no interest in understanding and simply wish to
throw out straw men, red herrings, and who knows what to complicate
a very simple concept.

--
Jim Pennino

Remove .spam.sux to reply.