On Sat, 13 Dec 2003 09:49:51 GMT, "Per Enocson"
My 165 m horizontal loop, which is up about 14 meters and has sort of
rhombic shape, is a great antenna, also for DX.
Currently, I feed it at a corner with a length of ( approx 12 m) 50 ohm RG
58 coax and enjoy a good SWR at my tx end (1:2 or less) on 160, 17 and 10
m. On other bands, SWR is much higher, which is easily fixed with my
automatic ATU (Elecraft KAT 100). I realize I may have some losses on these
bands, but try to comfort myself with the fact that the coax feed is quite
I now plan to go QRO, using a PA delivering 5-600 watts. I have a good old
Heathkit SA 2060 tuner, capable of a kw, with either unbalanced or balanced
(4:1 voltage balun) outputs.Here are a couple of the questions I am asking
1. Should I stick to coax feed or switch to ladder line? (reduce losses,
secure power handling capability)?
2. If I switch to ladder line, I prefer no taking it into the schack (afraid
of RFI and computer problems, also unpractical). How should I arrange
switching from ladder line to coax outside the schack window, to minimize
losses and "play it safe" when it comes to the balun specification. What
type of balun and what ratio should it have (1:1 better than 4:1)? Which
particular baluns/suppliers do you suggest?
3. Or, at the end of the day, would I be better off, from a loss point of
view, with sticking to coax while upgrading the coax to higher power
handling capability(I have some nice, thick RG 11 lying around here, it is
75 ohms though). The "loop skywire" in the ARRL Antenna Book advices us to
I realize that there is no simple answer to these questions, and am very
grateful for any advice from the group.
Thank you and happy holidays!
I also use a 160 m loop that this up 10 m here much the same as
yours.. I feed mine with 75 ohm coax to a 1:1 Choke balun just out
side the shack maybe 10 feet of coax then balanced line the rest of
the way it works great for me. I've in the past fed it with open wire
all the way to the tuner in the shack. But as you mentioned if gave
me troubles with unwanted RFI pickup from computer monitors ETC. I've
also fed it all the way with Coax (75 ohm] and that worked quite well
except on 12 & 10 meters .. So I guess what I'm saying is if the Coax
run is fairly short say 20 feet or so you won't notice a big
difference except maybe on 12 and 10 meters while feeding it with open
wire or coax.. The big loops just seem to work great. Good luck with
yours and all the best for the holidays.
73 Dave KC1DI