Posted by
KD8NNU on
Jan 11, 2012; 9:12pm
URL: http://elecraft.85.s1.nabble.com/ladderline-and-balun-question-tp7179004.html
Gents,
I have a ladder line and balun question that I hope someone can guide me
thru.
I had a good working antenna system with two antennas. First being an
Alpha Delta Dipole and the second a 2WL 160m loop antenna at 40 ft in
the air strung in trees. So the wire does touch the trees.
Dipole is fed with coax and choked at the feed point and the loop was
fed with 60 ft of ladder line to a 1:1 current balun then 25ft coax to
the shack tuner. Then the amp and radio. This combination was working
real well no RF problems in the shack.
I was advised that I would obtain better results for better SWR at
resonance and easier matching if I removed the 1:1 balun and went to a
4:1 balun. I made this change with everything else being the same. I
now had RF in the shack again.
I then added an isolation balun to the system by adding 6ft coax from
the output of the 4:1 to a balun designs 116du which is supposed to have
4500 ohms of choking impedance on 160m and over 5000 ohms choking
impedance on 80 and 40 meters. This did not eliminate the RF and I am
still having problems.
So here is the question, is it possible that with the combination of
length of the ladder line at 60ft plus the 6 ft plus 25 ft of coax I am
at a feed line length that will be a problem no matter what I do. I
keep looking at the internet to try and figure this out but I am
confused as some information I find says it only applies to 1:1 baluns
or other factors.
So anyone who can help me understand this feed line question I will be
greatly appreciative.
Thanks
Don
~73
Don
KD8NNU
______________________________________________________________
Elecraft mailing list
Home:
http://mailman.qth.net/mailman/listinfo/elecraftHelp:
http://mailman.qth.net/mmfaq.htmPost: mailto:
[hidden email]
This list hosted by:
http://www.qsl.netPlease help support this email list:
http://www.qsl.net/donate.html