Reg Edwards wrote:
All that's necessary is to erase the meter scales, or at least wash them
from our minds, and change the name of the SWR meter to the TLI.
(Transmitter Loading Indicator). Or some other more appropriate name.

Reg, what would you call the SWR meter calibrated for 300 ohms
that I have installed in the 300 ohm line to my 20m-10m dipole?
--
73, Cecil http://www.qsl.net/w5dxp



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Reg, what would you call the SWR meter calibrated for 300 ohms
that I have installed in the 300 ohm line to my 20m-10m dipole?
--
73, Cecil
============================
It depends on which end of the line you have installed it.

Or are you hedging your bets by locating it at the half-way point?

But wherever it is, it does not measure SWR.

Just because you may think it does, does not make it so!

But it's good to see you didn't disagree with me about TLI's
----
Reg

"Reg Edwards" wrote in message
...

"Ian White, G3SEK" wrote
And the conclusion of these experiments? That the concept of "reflected
power" is not helping us to understand anything.

============================

I've been saying for years, the so-called SWR-meter is itself the root of
the trouble - it has forward and reflected power scales on it. So it is
impossible to refer to it without becoming emotionally involved with the
highly misleading reflected power notion.

Furthermore, the confounded thing doesn't even measure SWR. How can it
measure SWR on a transmission line which does not exist?

It is a ridiculous, meaningless situation. People drag themseves off to
UHF
to air their knowledge about such things as echos, S-parameters,
circulators
and high power TV transmitters. Quite irrelevant to the notion of
reflected
power at 1.8 MHz.

All that's necessary is to erase the meter scales, or at least wash them
from our minds, and change the name of the SWR meter to the TLI.
(Transmitter Loading Indicator). Or some other more appropriate name.
----
Reg, G4FGQ

Reg

Just so I can get my thinking straight -- Does a slotted line measure
VSWR?

Jerry

Cecil Moore wrote:
You must be omnipotent in order to prove that
you are omniscient. I hope you are up to that task.

I'll try and remember that. 8-|

My challenge still stands. Please provide a standing wave without a
forward-traveling wave and a rearward-traveling wave. If you can't,
at least send me a joint of whatever you are smokin'.

Wow. Maybe I need to issue a "challenge".

How about this: If you can't prove that F does not equal m*a, then I am
right about whatever issue on which we disagree!

Is that how it works, Cecil? ;-)

73, Jim AC6XG

Just so I can get my thinking straight -- Does a slotted line measure
VSWR?
============================

No! A slotted line cannot measure VSWR.

But the VSWR on a slotted line can be measured. That is what it is there
for. The slot allows access by a probe to the inner conductor.

It does not allow or facillitate the measurement of VSWR on any line other
than on itself.

It is primarily used to make impedance measurements of R+jX etc in a
standards laboratory. The Ohmic Standard is the characteristic impedance,
Zo, of its own internal transmission line. Very accurate and stable.
----

Reg Edwards wrote:
But it's good to see you didn't disagree with me about TLI's

The 'brains' over on sci.physics.electromag tell me that it takes only
a couple of feet of 50 ohm coax on each side of an "SWR meter" to
guarantee that it exists in a 50 ohm environment. I indeed do have
three feet of RG-400 on each side of mine.
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Kelley wrote:
How about this: If you can't prove that F does not equal m*a, then I am
right about whatever issue on which we disagree!

Is that how it works, Cecil? ;-)

That's how your logic obviously works, Jim. Most of us know
that it is impossible to prove a negative except for a binary
outcome.

Please, pretty please with cream and sugar on it, provide just
one single example of a standing wave without forward-traveling
or rearward-traveling components. That is certainly not too
much to ask.
--
73, Cecil http://www.qsl.net/w5dxp



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Reg Edwards wrote:

"Ian White, G3SEK" wrote
And the conclusion of these experiments? That the concept of "reflected
power" is not helping us to understand anything.

============================

I've been saying for years, the so-called SWR-meter is itself the root of
the trouble - it has forward and reflected power scales on it. So it is
impossible to refer to it without becoming emotionally involved with the
highly misleading reflected power notion.

Furthermore, the confounded thing doesn't even measure SWR. How can it
measure SWR on a transmission line which does not exist?

It is a ridiculous, meaningless situation. People drag themseves off to UHF
to air their knowledge about such things as echos, S-parameters, circulators
and high power TV transmitters. Quite irrelevant to the notion of reflected
power at 1.8 MHz.

All that's necessary is to erase the meter scales, or at least wash them
from our minds, and change the name of the SWR meter to the TLI.
(Transmitter Loading Indicator). Or some other more appropriate name.

Technically correct, but far too late. "SWR" is everywhere - the genie
is out of the bottle, and it won't go back.

To expand on what Reg already knows, but clear needs to be said again
and again...


The only way forward is for everybody to understand that SWR numbers are
just one of several alternatives for judging the "goodness" of an
impedance match to some specified reference impedance. Other
alternatives include reflection coefficient, return loss, gamma, S11,
etc.

All these alternatives are equally valid, and any one can easily be
converted to any other by doing a small amount of math. RF engineers do
it all the time, and it's absolutely no big deal.

If you're only using "SWR" as a number that indicates the goodness of an
impedance match, you can legitimately apply it to *anything* that
possesses an impedance (it doesn't need to have waves standing on it).

The discussion goes off the rails when someone starts to imagine that an
"SWR meter" is truly *measuring* standing wave ratio. It isn't - it is
actually measuring one of those other quantities (magnitude of
reflection coefficient). Then there has to be a mathematical conversion
from that number into the more familiar SWR number, which is done by
calibrating the meter scale in a specific non-linear way.

It's vital to understand that difference: the instrument is *calibrated*
in SWR, but it is actually *measuring* something else.

Likewise it's a mistake to believe that a Bird Thruline wattmeter is
measuring "forward and reflected watts". It is just another gadget for
measuring reflection coefficient, with a fixed sensitivity that allows
the meter scale to be calibrated in watts. But it's only a calibration
in terms of power - the Bird is not making a power measurement.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

The ONLY thing an SWR meter measures is the "Magnitude of the reflection
coefficient relative to an arbitrary value of Ro", where Ro is usually 50
ohms. It actually throws away the other half of the possible information,
ie., the "Reflection Coefficient Angle".

99.9 percent of radio amateurs have never heard of such a quantity. There's
no reason why they should. It's of no practical use or interest.

But they are VERY interested in whether or not their transmitter is
correctly loaded with 50+j0 ohms during transmissions and a simple
indicating instrument is essential.

Isn't it time some enterprising manufacturer came into the market?
---
Reg, G4FGQ


"Ian White, G3SEK" wrote in message
...
Reg Edwards wrote:

"Ian White, G3SEK" wrote
And the conclusion of these experiments? That the concept of "reflected
power" is not helping us to understand anything.

============================

I've been saying for years, the so-called SWR-meter is itself the root of
the trouble - it has forward and reflected power scales on it. So it is
impossible to refer to it without becoming emotionally involved with the
highly misleading reflected power notion.

Furthermore, the confounded thing doesn't even measure SWR. How can it
measure SWR on a transmission line which does not exist?

It is a ridiculous, meaningless situation. People drag themseves off to
UHF
to air their knowledge about such things as echos, S-parameters,
circulators
and high power TV transmitters. Quite irrelevant to the notion of
reflected
power at 1.8 MHz.

All that's necessary is to erase the meter scales, or at least wash them
from our minds, and change the name of the SWR meter to the TLI.
(Transmitter Loading Indicator). Or some other more appropriate name.

Technically correct, but far too late. "SWR" is everywhere - the genie
is out of the bottle, and it won't go back.

To expand on what Reg already knows, but clear needs to be said again
and again...


The only way forward is for everybody to understand that SWR numbers are
just one of several alternatives for judging the "goodness" of an
impedance match to some specified reference impedance. Other
alternatives include reflection coefficient, return loss, gamma, S11,
etc.

All these alternatives are equally valid, and any one can easily be
converted to any other by doing a small amount of math. RF engineers do
it all the time, and it's absolutely no big deal.

If you're only using "SWR" as a number that indicates the goodness of an
impedance match, you can legitimately apply it to *anything* that
possesses an impedance (it doesn't need to have waves standing on it).

The discussion goes off the rails when someone starts to imagine that an
"SWR meter" is truly *measuring* standing wave ratio. It isn't - it is
actually measuring one of those other quantities (magnitude of
reflection coefficient). Then there has to be a mathematical conversion
from that number into the more familiar SWR number, which is done by
calibrating the meter scale in a specific non-linear way.

It's vital to understand that difference: the instrument is *calibrated*
in SWR, but it is actually *measuring* something else.

Likewise it's a mistake to believe that a Bird Thruline wattmeter is
measuring "forward and reflected watts". It is just another gadget for
measuring reflection coefficient, with a fixed sensitivity that allows
the meter scale to be calibrated in watts. But it's only a calibration
in terms of power - the Bird is not making a power measurement.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

But they are VERY interested in whether or not their transmitter is
correctly loaded with 50+j0 ohms during transmissions and a simple
indicating instrument is essential.

Isn't it time some enterprising manufacturer came into the market?
---
Reg, G4FGQ

The first such instrument will probably have "Made in China" on its back.