In message <[EMAIL PROTECTED]>, Paul Webb
<[EMAIL PROTECTED]> writes
Hi All
I have been playing with my KX1 in the back yard the last week or so and
found that about 26ft of wire in the hot side of the bnc connector and about
the same to the cold side gets me a good match with the built in ATU on
40,30,20m
Now if I use the same wires but add 20ft of coax between the radio and these
wires I find it very hard to get a match on any band, do I need to use a
balun at the end of the coax?
Any thoughts
Paul
Hi Paul,
I believe you are on a hiding to nothing attempting to reproduce the
results via a length of coax cable. Remember those initial results were
obtained with the ATU connected directly to the antenna. Everything
after the ATU is effectively the antenna and is likely to radiate,
including the coax. Adding a balun will do absolutely nothing except to
change the electrical antenna length (where the antenna in this case is
the coax and the original wires), your coax will still radiate and you
are likely to get poor results.
With this sort of antenna the ATU must *always* be at the antenna end of
the feeder, whether that be directly after the ATU in the KX1 as in your
initial trials, or at the antenna end of the 20 foot of coax as you
attempted later. The only exception to this is when the antenna
presents an electrical quarter wave or odd multiple thereof. In those
cases, no ATU is necessary.
Trev G3ZYY
--
Trevor Day
UKSMG #217
www.uksmg.org
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