On Sun, 03 Dec 2006 23:13:38 -0500, John Ferrell
wrote:

I am considering purchasing a remote auto tuner for my continuing
tinkering with verticals. My current focus is on 80-160 meters with
33+ foot verticals. The auto tuners specs claim a max inductance of
around 32 uh. The tuners computed with the ARRL program TLW20 require
much larger values of inductance.


Did you model the exact circuit of the SGC tuner? IIRC they use a
l/pi-l configuration and an autotransformer.

Will the Auto tuner (SGC-237) that claims to match any wire greater
than 28 feet long really do it?

The demands on the tuner will depend on how good a ground system you
build. If you use a poor ground system, a side benefit of the poor
efficiency is a subtantial amount of resistance in the feedpoint
impedance, though you are probably still looking at thousands of ohms
of capacitive reactance. If on the other hand you have an outstanding
ground system, the very low value of feedpoint R becomes challenging
for the tuner, and the efficiency you saved with the gound system
might be lost in the tuner.

Of course, the other option is to lengthen the vertical to raise the
radiation resistance so that it is not totally swamped by ground
system resistance.

Back to you question, will you get a match? If the tuner lives up to
its specification, you should... but you are looking at the world
through your VSWR meter, and that is a very limited view!

Owen
--

On Mon, 04 Dec 2006 06:49:11 GMT, Owen Duffy wrote:

On Sun, 03 Dec 2006 23:13:38 -0500, John Ferrell
wrote:

I am considering purchasing a remote auto tuner for my continuing
tinkering with verticals. My current focus is on 80-160 meters with
33+ foot verticals. The auto tuners specs claim a max inductance of
around 32 uh. The tuners computed with the ARRL program TLW20 require
much larger values of inductance.


Did you model the exact circuit of the SGC tuner? IIRC they use a
l/pi-l configuration and an autotransformer.

Will the Auto tuner (SGC-237) that claims to match any wire greater
than 28 feet long really do it?

The demands on the tuner will depend on how good a ground system you
build. If you use a poor ground system, a side benefit of the poor
efficiency is a subtantial amount of resistance in the feedpoint
impedance, though you are probably still looking at thousands of ohms
of capacitive reactance. If on the other hand you have an outstanding
ground system, the very low value of feedpoint R becomes challenging
for the tuner, and the efficiency you saved with the gound system
might be lost in the tuner.

Of course, the other option is to lengthen the vertical to raise the
radiation resistance so that it is not totally swamped by ground
system resistance.

Back to you question, will you get a match? If the tuner lives up to
its specification, you should... but you are looking at the world
through your VSWR meter, and that is a very limited view!

Owen
The SGC-237 is on order!
I appreciate the help in making my decision.
John Ferrell W8CCW

Nice tuner... Just remember John, no one can be too rich, too thin, or
have too many radials...

denny / k8do

On 5 Dec 2006 06:25:25 -0800, "Denny" wrote:

Nice tuner... Just remember John, no one can be too rich, too thin, or
have too many radials...

denny / k8do
I will never have any of those problems...!
John Ferrell W8CCW

On Mon, 04 Dec 2006 20:50:54 -0500, John Ferrell
wrote:

On Mon, 04 Dec 2006 06:49:11 GMT, Owen Duffy wrote:

On Sun, 03 Dec 2006 23:13:38 -0500, John Ferrell
wrote:

I am considering purchasing a remote auto tuner for my continuing
tinkering with verticals. My current focus is on 80-160 meters with
33+ foot verticals. The auto tuners specs claim a max inductance of
....
The SGC-237 is on order!
I appreciate the help in making my decision.

If you want to improve efficiency on 160m, think about raising the
radiation resistance and / or reducing the earth loss.

Possibilities to raise Rr include inductive loading high up, longer
radiator, capacity hat, more than one of the above.

Owen
--