Also, consider making sure you have the latest firmware updates. I have
also experienced the situation where the K3 internal tuner will tune my
200' ladder-line fed doublet but the KAT500 will not. I'm hoping that
subsequent updates will improve the KAT500's algorithms.
73, Doug -- K0DXV
On 5/19/2014 8:50 PM, Don Wilhelm wrote:
David,
What have you changed on that antenna system since it last "worked"?
The length of the antenna is only part of the story, because the
length of the feedline is also an important parameter. If you changed
the feedline, that can make the difference between working and not
working.
The length consideration should be the feedline length plus 1/2 of the
antenna length. If that comes close to a 1/2 wavelength, the antenna
will be hard to feed since it represents a high impedance to the
tuner. Likewise, if the feedline plus half antenna is an odd multiple
of 1/4 wavelength, it will present a very low impedance to the tuner
which can be difficult to match.
Adding (or subtracting) a bit of feedline - add or subtract 1/8
wavelength at the problem frequency - can make all the difference
between obtaining a match or not.
73,
Don W3FPR
On 5/19/2014 9:26 PM, David Inger wrote:
I have a fairly early KAT500 tuner (#275). I am using it to tune
several
antennas. Recently it has stopped finding acceptable matches to a
ladderline-fed 110 ft. dipole. This problem is only on 40-meters.
The SWR
anywhere in that band is around 8:1. The tuner works great on all other
bands (well, not so much on 160, but that's the antenna's problem).
I also
have a 43-ft vertical and the tuner matches fine on that antenna. I
replaced all intervening coax jumpers and even the 1:1 current balun
at the
transition of the ladderline to the coax in the shack. None of the
above
help.
Interestingly, when I bypass the KAT500 and enable the internal tuner
in the
K3, everything works fine, including matching 40-meters. I have also
done a
reset using the KAT500 utility program; still no help.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
