On 30-Dec-05, at 2:01 PM, Michael Babineau wrote:
wayne burdick <[EMAIL PROTECTED]> wrote :
One question I'm sure to get is
whether the KXAT1 ATU is usable on 80 meters. The answer? Yes, but the
KXAT1 wasn't designed to cover this band, so it will only help with
specific end-fed wire antenna lengths to be determined.
I would suggest that someone investigate how well a 26.5 meter (ie
approx 87 ft)
long wire matches with the KXAT1.
This is one of the "magic" lengths suggested as a good compromise for
matching
on most of the amateur bands, by Alan Chester, G3CCB (SK) in his RADCOM
article titled "Taming the End-Fed Wire". This may be your best bet
for a wire
that will easily match on 80m/40m/30m/ and 20m with a tuner, as it
avoids multiples
of half wavelengths (high impedance) on these bands.
I went back through my notes and it looks like I actually did try an
end-fed 87 foot wire with
the KXAT1 (sometimes it pays to write things down) .
87 foot inverted L supported by two 20 foot fishing poles and using
five 16 foot radials on the ground
KXAT1
20m 1:1 SWR
30m 1.2:1 SWR
40m 3.9: 1 SWR *****
BTW, using the same wire but in an inverted U configuration with the
same two fishing poles and radial system
I had the following results with the K1 :
KAT1
17m 1.0:1 SWR
20m 1.0:1 SWR
30M 1.1:1 SWR
40m 1.7:1 SWR
***** It looks like lengthening the wire to perhaps 28 meters (about 92
feet ) would improve the match on 40M, as 26.5m is almost
a no-go length for 40m. This however might negatively impact the match
on 30m. Eighty meters and 20m should be ok with
a slightly longer wire. One option would be to use a 26.5m wire but
have an extra 5 foot clip on section to help
with the match on 40m, some experimentation would be required.
Michael VE3WMB
P.S. If you don't care about the match on 30m it looks like a 15m wire
(about 49 feet) should be a good length
to try for 80m / 40m and 20m. In theory, this should be a very easy
length to match on 80m as you would only need
about 10 to 14 micro-Henries of series inductance to achieve a match in
the 25 to 50 ohm range.
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