I bought the KAT100 tuner as a convenience item
and did not think it would be as efficient as other
tuners in the shack. I judge the merit of tuners
by measuring the RF current in the ladder line
going to my 234 foot open loop around the house.
It is a beast to feed on 160 and 40 meters, and much
easier on all the other bands. I have the actual
conjugate impedance measurements on all the
bands around here somewhere, but lucky for the
group, I can't find my data at the moment. I have
measured current using thermocouple and home-
built clamp-on ammeters.
My Palstar AT1500BAL is a no-compromise balanced
output tuner. There is a 1:1 balun on the input and
the tuner consists of an L circuit for each side of the
feedline. It is configurable for high and low
impedances, with very heavy duty relays changing
the variable capacitors from the input of the inductor
to the output. It has beat out the 300 watt version of
the Johnson Matchbox. I have not had access to
the KW version, but an article by Frank Witt in QST several years
ago showed the 300 watt version to be superior to its
big brother. The Palstar has also beat my MFJ KW tuner that I have
used floating from ground with a 1:1 balun at the input.
There was no balun at the output and the MFJ was more
efficient in that configuration than using the
built-in 4:1 balun. (See the ARRL Antenna Compendium
Volume 2, page 172, "Some Additional Aspects of
the Balun Problem.")
I was quite surprised to see the KAT100 tuner to
put out essentially the same currents on all bands
as the Palstar balanced tuner! So a convenience
it is, but also it is a good tuner! I have also used
it, at Wayne's suggestion, to feed a portable 23
foot vertical with elevated 23 foot radials fed with
300 ohm ladder line and 1:1 balun on the output
of the K2. This is antenna is used on 40 through
10 meters and has won me thousands of QSO's.
There I have measured current at the base of the
vertical radiator. The Elecraft tuner beat my manual
300 watt MFJ tuner feeding the antenna directly at the base.
It also outperforms the LDG RT-11 also at the base of
that vertical with no feeline between the tuner and
antenna.
I still use the giant Palstar as the KAT100 won't
work with my Sierra or my KW Japan Radio linear!
For the K2 barefoot, the KAT100 can't be beat, as far as I
can see.
Andy W9NJY
Milwaukee
K2 ser 2651
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