Thread: Antenna Tuner
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Old December 14th 04, 02:27 PM
Jack Painter
 
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Hi
I tried to reply to your post, but it does not seem to have made it..so
here is another try:
This is a quote taken from one site:
Of interest is the 1:1 balun mounted at the input of the tuner (rather
than the output where it would be exposed to highly reactive loads).
The various components are floated above chassis ground. When properly
adjusted, the balun sees a 50 ohm load both at the imput from the
transmitter and at the output. Its not a perfect replacement for the
link coupled circuits of yesteryear, but in my experience so far, it
perfoms significantly better than competing tuners employing 4:1
baluns. I've tried a few of these matching networks and not one of them
provided an output to tuned feeders even close to being balanced. The
AT4K-BAL is a leg up on this account.
I have seen dozens of other sites with the same info, including several
ARRL articles.
Thanks


Your first post did make it, and I also found that reference that shed no
light, but further:

http://fermi.la.asu.edu/w9cf/articles/balun/ (quoted below)

4 Baluns on the input and output of unbalanced tuners:
Roy, W7EL, worked out the math for moving a current balun from output to
input of an unbalanced tuner using his model of a choke balun and found that
essentially nothing changed.

....the most sensible place to put a balun is on an unbalanced tuner's
output, like it is on nearly all commercial tuners, and not on its input

--

Interesting theory presented there, but does not support the wives tale
either.

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