Cecil Moore wrote:
Dieter Kiel wrote:
As the tuner is used to match the impedance of the radio to the line it
will effect the power getting to the antenna or the signal received from
the antenna if it is passed through the tuner.

If the power getting to the antenna is measurable, then
the tuner is causing something to happen at the antenna.
It is doing more than just making the transmitter happy.
After all, a dummy load makes the transmitter just as
happy as a tuner.

Cecil;

An antenna tuner does not and can not and will not make any physical or
electrical changes to any antenna it is attached to. It will, however,
make electrical changes to an "ANTENNA SYSTEM" such that a transmitter
or receiver will react to the system more efficiently.

Take a dummy load that exhibits a characteristic impedance of say 75
ohms and hook it up to a transmitter that exhibits a characteristic
impedance of 50 ohms. I guarantee that the transmitter won't like it as
well as a dummy load that exhibits a characteristic impedance of 50
ohms. All impedances are purely resistive with no inductive component.
Place a tuner in the circuit and adjust it for best conditions. The
transmitter will think it is looking at 50 ohms not 75.

Dave WD9BDZ

wrote:
...100% efficient? The only thing I have ever had that was 100%
efficient was my 'Ex', which she pointed out to me quite often. So,
using a tuner that got just a tiny bit 'warm' from it's inefficiency
just wasn't/isn't that big'a deal. When it became noticeably 'warm',
it was because I was trying to match something that just was not very
close to reasonable. Then again, it sort of depends on the tuner you
happen to be using, it's 'usable' impedance matching range, just how
'robust' the thing happens to be built, and what you are trying to do
with it to start with. There are limits. How often you approach
those limits sort of defines how much heat you will see, they make
pretty nice coffee warmers at times , not the best idea in the
world, but...
- 'Doc

And just for 'grins', for those who do not 'approve' of using a tuner,
what do you think those gama, delta, and other variety of thingys on
the feed point of that beam are?
(if that don't stir the 'worm soup' up a little, I just haven't had
enough coffee yet. I'm still warming it on the tuner.)


For more grins, what do you think the "LOAD" and "TUNE" knobs on an
older tube transmitter are? They match the output power tube impedance
to the antenna system impedance. If you don't believe me mistune a tube
transmitter and feel the warmth come from the finals. Have a spare in
stock for when you are done.

Dave WD9BDZ

Michael Coslo wrote:
Yeah. This is probably the first time some random poster over at QRZ or
Eham has been wrong! 8^)

What is troubling is that the myth seems to be approaching
50% of the posters. If all an antenna tuner does is make the
transmitter happy, it is no better than a dummy load.
--
73, Cecil http://www.w5dxp.com

David G. Nagel wrote:
An antenna tuner does not and can not and will not make any physical or
electrical changes to any antenna it is attached to.

Seems to me that delivery of the maximum available power
to the radiation resistance of an antenna is certainly
a physical/electrical change capable, in the extreme, of
melting the antenna.

Consider what a 1kw amp could do to a 40m hamstick used
on 75m when matched with a 1kw antenna tuner.
--
73, Cecil http://www.w5dxp.com

"David G. Nagel" wrote in message
...
wrote:
For more grins, what do you think the "LOAD" and "TUNE" knobs on an older
tube transmitter are? They match the output power tube impedance to the
antenna system impedance. If you don't believe me mistune a tube
transmitter and feel the warmth come from the finals. Have a spare in
stock for when you are done.

Dave WD9BDZ

I think I am trying to say the same thing.

One has to define where the matching system of the final amplifier stops and
the antenna system starts. I look at an antenna tuner that is within a few
feet of the transmitter as an extention of the matching network between the
amplifier device (tube or transistor) and the load which starts with the
transmission line.

If the antenna tuner is actually at the antenna, then it is a matching
device for the antenna and not in the scope of this discussion.

Is the automatic internal antenna tuner such as in my Icom746 pro really an
antenna tuner or is it just taking the place of some knobs that I could turn
such as in a Heathkit sb100 ? All that is being done in either case is to
match the amplifing device to whatever load is put to it.
I thnk it is just a mater of what someone wants to call it at the time.

Cecil Moore wrote:
David G. Nagel wrote:
An antenna tuner does not and can not and will not make any physical
or electrical changes to any antenna it is attached to.

Seems to me that delivery of the maximum available power
to the radiation resistance of an antenna is certainly
a physical/electrical change capable, in the extreme, of
melting the antenna.

Consider what a 1kw amp could do to a 40m hamstick used
on 75m when matched with a 1kw antenna tuner.

Cecil;

How much change in physical length or diameter of wire does an antenna
tuner make to an antenna?

Dave

David G. Nagel wrote:
Cecil Moore wrote:
Consider what a 1kw amp could do to a 40m hamstick used
on 75m when matched with a 1kw antenna tuner.

How much change in physical length or diameter of wire does an antenna
tuner make to an antenna?

In the above example, it vaporizes the hamstick wire.
IMO, that is quite a change.
--
73, Cecil http://www.w5dxp.com

AI4QJ wrote:
You can take advantage of the "information" provided
by the transmitter, with reference to its Z0 match condition, by merely
observing the maximum available output power.

The point is, it can be monitored *at the antenna*
thus proving that a tuner does indeed have an effect
at the antenna.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
AI4QJ wrote:

You can take advantage of the "information" provided by the
transmitter, with reference to its Z0 match condition, by merely
observing the maximum available output power.


The point is, it can be monitored *at the antenna*
thus proving that a tuner does indeed have an effect
at the antenna.

An effect "at" the antenna is not the same as an effect "on" the
antenna. Which did you mean in your OP?
Alan

Alan Peake wrote:
An effect "at" the antenna is not the same as an effect "on" the
antenna. Which did you mean in your OP?

The subject line says it all - "at the antenna".
--
73, Cecil http://www.w5dxp.com