Well, with the remote autotuner you will have less RF in the shack...
But even then I would hang ground radials off the tuner case to keep
it at lower voltage potentials...

Definitely! One of the characteristics of the SGC autotuners is that
they seem to *require* a really good RF ground. Their tuning
circuitry "wants" to work into a ground connection which has a lower
impedance than the wire. SGC's manual makes this point repeatedly,
and identifies "grounding problems" (poor bonding, high inductance,
etc.) as the commonest cause of "Hey, this thing won't tune" problems
with their autotuners.

My own experience with a used, older-model SGC 230 (so old it's in a
non-waterproof metal case) seems to back this up. When used with a
relatively simple ground, the tuner has serious problems in achieving
a match, and frequently won't ever find one.

I tend to think that these arbitrary-wire tuners work best in their
original environment - bolted to a really big, solid chunk of metal
such as a ship body or a tank.

Another "gotcha" - the tuner I have, at least, can become seriously
"confused" if you try to use it with a radio that has aggressive "high
SWR power reduction" circuitry to protect the finals. In such a radio
(my Kenwood TS-2000 is one), the output power jumps around a lot as
the autotuner tries different L-network match settings, and the tuner
firmware seems to misinterpret these transmitter power changes and
never actually finds a low-SWR match. The same tuner, and the same
wire and grounding setup, will often match within a few seconds when
power is applied from another transmitter which doesn't alter its
output power so abruptly (e.g. a Ten-Tec Scout 555).

I've given up trying to use my old SGC-230 - it's so quirky that I
just can't depend on it to work acceptably in my environment, with my
radio.

Other vendors' autotuners may be less of a problem in this respect.

Since you are willing to spring for an SGC, etc. given your
description of your site I would think about an off center fed wire
antenna... Run your longwire through the trees... Roughly an 1/8 wave
lowest band back from one end of the antenna drop a vertical wire
to the ground and use the tuner to feed the end of the drop wire... A
ground stake and some radials and you are likely to be in business...

I'd recommend following SGC's recommendations... which probably add up
to "lots of heavy radials".

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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