The results almost totally depend on the length of the ladder line. At
certain lengths, it will act as an impedance transformer and could load
your 80m dipole quite well. An 80m dipole on 160 will have a low
impedance at the feed point. A quarter wave of ladder line will
transform that impedance to a higher impedance. A half wave of ladder
line will give the same impedance (no transformer effect.)
If you have something near a half wave of ladder line, the 4:1 balun is
totally wrong since it will transform a low impedance to one 4x lower!
Try it with a 1: balun and see if the SWR improves or not.
As for actual, honest SWR readings, I assume that most meters are
unreliable in the actual readings when the SWR gets high, especially
10:1 and above. They are really built to operate in the 50 ohm range,
not 500 or 1000.
BTW, IMO the KAT500 is one of the best tuners I've used and I've been
building or using them for over 50 years.
Ken WA8JXM
On 11/4/15 3:59 PM, Phil Hystad wrote:
First, this is a curiosity question about KAT500 utility only. I don’t intend
to use my antenna on 160 meters.
I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1 Balun to
Coax for last 20 feet. This antenna works excellently in concert with the
KAT500 for 80, 40, and 30 meter bands. I don’t use it with other bands.
This weekend, I was curious as to how close (or far) the KAT500 could bring the
antenna in for the 160 meter band. I knew that it would not work though I was
wondering how bad it would be.
So, as I expected, the tuning never closed in on a descent SWR, the best I saw
on one test only was SWR about 49:1 as reported by the KAT500 utility. But,
the BYPASS SWR reported was about 11:1.
Further tests showed varying bad reports of incomplete tuned SWR while also
showing a much lower BYPASS SWR (under 13:1). According to my own tests of the
impedance for the antenna on 160 meters, the BYPASS SWR is bogus.
So, I am assuming that unless the KAT500 reaches a tuned SWR value under 1.5:1
(or, whatever threshold I set), the BYPASS SWR is totally meaningless.
73, phil, K7PEH
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