wrote
Hello Jack
Yes, the tuner is required, because I use a balanced line to feed a
multiband doublet.
The issue is placeing a 1:1 balun at the input of the tuner, rather
than the output. In order to do that with an existing T match type
tuner, all components must be isolated from ground. This is uncommon,
because a typical T match grounds one side of the inductor.
I have read that a 1:1 balun at the input of a T match is desireable
over a 4:1 at the output.
Thanks

Hi Jim,

I can't imagine what's possibly gained by 1:1 in front of the tuner v. 4:1
(when applicable, some antennas recommend this, including for twin-lead)
after it. Can you recall the writing you saw the recommendation to isolate
from ground before the tuner? I just don't see what it will do for you, but
as I said there is at least one good reason not to do so. Ungrounded and
especially unbonded equipment should be disconnected from antennas and power
supplies before the chance of a thunderstorm. An exception could be if you
totally isolate the antennas from ground, and no balun can safely do that.
But a similar principle called a high voltage isolation transformer could,
and so could a fiber optic isolation transformer. Both are pretty expensive
alternatives to staying with generally accepted lightning protection plans
for the shack. Even if you intend to toss the feed out the window before a
storm, I'm still curious what is gained by a 1:1 between transceiver and
transmatch.

73,
Jack