"chuck" wrote
Jack, I do think there's some confusion here. In cases where the balun
is a part of the tuner input, the tuner chassis is usually connected
directly to the transmitter chassis through the normal coax. You can
ground the tuner chassis to an external earth ground if you so wish.
Internally, the balanced output of the balun is connected to the "T"
components at the input side. The coil, of course is not at chassis rf
ground potential, but that is not relevant. It is, however, at DC ground
potential (via the balun winding). I don't see any additional lightning
issues associated with placing the balun at the tuner input.

73,
Chuck

Hi Chuck (and Jim), I was unclear on what the benefits would be, hence my
questions to Jim (and the Group). But the file I referenced earlier also
questioned the benefits, and explained the need for floating the tuner when
a Balun i used in front of it, which would be a very bad move if lightning
protection was an issue. There would be no ground connection to the tuner,
leaving it as a sacrifice gear but inside the shack!. That's not all that
uncommon to sacrifice a tuner by the way, but usually seen where the tuner
is up in the air at the feedpoint. Marine applications often use this
configuration. I don't! Hi!
--
6. Conclusions
As noted by Roy Lewallen, W7EL,[2] putting a choke balun on the input of an
unbalanced tuner to drive a balanced line is useless. It introduces a
``hot'' tuner case which must be isolated with no benefit over putting the
balun on the output.
--
I agree that a 4:1 after the tuner (or after coax from tuner to feedpoint
where laddr-line begins) is a compromise at best, offering beneficial
performance at some frequencies and degradation at others. All a matter of
choices I guess, make the decision that's safe (first) and best for your
needs after that.

As always, I find this group shakes out great comments and explanations. If
Roy L wants to add something to this I'm sure we would all be interested.


73,
Jack


wrote:
And yes you can stand-by-for-fireworks if you think lightning

protection

isn't an issue. Anyone that thinks "floating equipment chassis"

(isolated

from ground) is a good plan, lives in a place where lighting is

something

they watch only on the Discovery Channel.

73,
Jack



Jack
Let me assure you, my station is well grounded, Hi! I even have an
abnormal passion regarding grounds.
My remark was in regarding to a "floating" balanced antenna tuner,
which is not grounded anymore than is a balanced line fed doublet.
Certainly everything before the tuner is well grounded. I even have a
spark gap type lightning protector on the balanced feeds.
As far as the debate regarding baluns at the input or output, I would
be delighted to be convinced that it either does not matter, or is
better at the output..because it makes my life a lot simpler. Right
now I am using about 5 feet or so of LMR400 from my unbalanced tuner to
a Radio Works remote balun, terminated with 300 ohm transmitting
twinlead, feeding a 40 meter doublet. Works like gangbusters.
Jim