[Elecraft] Baluns and 450 ohm line

[Stuart Rohre]

Earl,

Actually at QRP levels, the usual unbalanced T tuner with balun on its
output works multiband just fine feeding a 450 ohm line with a 4:1 balun as
is built into all the common commercial T matchers.  We placed in top 10 of
field day with such a set up over past 7 years.  If you get some band with a
sensitivity to the length of 450 ohm feeder you are using, add 5 or 10 feet
and retune.  True, we do not worry what impedance the line is seeing, just
that it be in the range of the transmatch plus line we use.  The matcher
adjusts the whole line and antenna combination, as seen from the fed end, so
it is not important with low loss parallel lines of higher impedance than
coax, to match impedances in the antenna system.  You just want the input
side of the transmatch to present close to 50 ohms to the rig.  The higher
impedance lines have much lower losses than the coax tuned lines in the
multiband operations.  That is the advantage as well as lower weight on the
center of the multiband large wire antennas we use.  Our largest was an 849
foot around loop last year.

Some years, we add a good quality 1:4  current balun to the output of an
unbalanced L network transmatch and this too works well with our large
wires.
72,
Stuart K5KVH