[Elecraft] Where does the tuner go

[Andrew Catanzaro]

Message: 14
Date: Sun, 07 Sep 2003 09:04:39 -0700
From: Phil Wheeler <w7ox@earthlink.net>
Organization: Outstanding
To: Elecraft <elecraft@mailman.qth.net>
Subject: Re: [Elecraft] Remote Antenna Tuner

Jim Campbell wrote:

> Phil,
>
> It would be more helpful for me, and perhaps many on the list if you
> explained why this is not true.
> Would it be more correct if he had said "works better" instead of
> "needs"?



Not even works better.

This is an old debate, long settled.  There are many web sites with
discussions, books, articles, etc -- some quite erudite.  Frankly I do
not have time nor energy to rehash it.   Perhaps someone else has the
motivation.  Or you can use antenna and transmission line analyses and
come to your own conclusions -- as I did once many years ago.

In fact the xyl wants me to get off the computer and go hiking NOW
:-)

73, Phil

**********************************************************************
****
Phil,

Hope you are back from your hike . . .
The issue of where a tuner goes does not have a single answer.
I debated Wayne on this three years ago in Dayton, and we used
Roy Lewellan as a reference.   Wayne wasn't satisfied with Roy's
response.
So last spring, the subject came up again very briefly on the
reflector.  Referencing W7EL, wasn't good
enough to get my point across, so I asked LC Cebik.
Here's his response.  Until Elecraft provides a good way to remote
their tuner, which appears to otherwise outperform my LDG RT-11,
the LDG is staying outside driving the vertical element of my antenna.

73,
Andy  W9NJY Milwaukee
K2   Sierra

**********************************************************************
****


Andy,

Yes, indeed, in a salt=water environment, a vertical shows exceptional
performance relative to the same antenna over lossy soil--not just in
the
Midwest.  Notice in your modeling program the differences in the
conductivity and dielectric constant.  Hence, ships continue to use
such
antennas very effectively.

The key benefit of using a tuner at the base of the antenna is the
difficulty of dressing a parallel transmission line close to the
ground
without introducing people hazards as a trip-wire or wire balance
disruptions.  Experiments I have read on running the wire underground
even
in large conduit and well centered show increased losses.  Close to
ground,
we require at least a foot or more clearance.  There is an old rule of
thumb
about keeping the line at least 3-line widths clear of any metal
objects
passed, but that applies to small metallic objects.  When run parallel
to
the ground, we need considerable more clearance to avoid the
accumulation of
individually small affects.

If you use the vertical elevated from the ground--like on a house or
garage
roof--then you can have a relatively free run without interfering
objects.
However, for ground level installations, if you have a remote tuner
designed
for the weather, then placing it at the antenna base with coax (and a
control cable) to the shack my be the least problematical solution in
the
long run.

If you use a balun in the shack, I recommend a high quality 1:1 balun.
On
some bands, the impedance may al;ready be low, and a 4:1
transformation
downward may challenge your tuner.

Hope this helps a little.

-73-

LB, W4RNL
======================================================================
===
L. B. Cebik, W4RNL              /\   *    /  /    /     tel:
865-938-6335
1434 High Mesa Drive        /\ /  \/\    ----)(--- 
http://www.cebik.com
Knoxville, TN 37938-4443   /  /   /  \  /  / || / e-mail:
cebik@cebik.com
USA                       /  /   /    \      ||
W4RNL@ARRL.org
----- Original Message ----- 
From: Andrew Catanzaro
To: cebik@cebik.com
Sent: Sunday, April 27, 2003 1:56 AM
Subject: Where does the tuner go?


LB,

I have been operating portable in Bonaire -Netherland Antilles
with a 19 foot vertical on 10 through 40 meters on many trips.
I use a coax-fed autotuner at the base of the vertical radiator and
two 1/4 wave radials lying on
the ground for each band.   I am essentially on the sea shore
and Bonaire is a tiny island with many inland salt-water lakes.
I've modeled the antenna on different bands as though I were over salt
water
and the antenna analyzer puts out results that are surprisingly close
to the model.  Obviously the antenna is much more efficient in that
environment than it would be operating over the soil we have here
in the Midwest.  I've been very pleased with the results.

My question is it really necessary to put the tuner outside my cabin?
Would I get the same efficiency by feeding the vertical with a good
quality balanced
feedline and using a high-quality current balun to couple the feedline
to the same tuner inside the cabin?
Would the feedline radiate?  If I used open wire line or ladder line,
how high above the
salt-encrusted soil should it be?

Thanks for your time!

Andy W9NJY
Milwaukee WI