I have limited experience with a wire fed via a 9:1 "un-un", but that experience was VERY good.
I borrowed a KX3 from a friend when I went to visit family in FL a few years ago. I had a 9:1 "un-un", about 126' of wire, and 50 feet of RG8-X. I got the feedpoint, up 30 feet into a tree, and the far end over limb of another tree. That point was about 15 feet above ground. About 7 feed of the wire hung straight down toward the ground. I used a 30 foot counterpoise, that hung down from the "un-un", along with the coax. I did not try 160 (this was in mid-summer), but the ATU in the KX3 achieved a good enough match on 80 through 10 meters... and I made a few hundred QSOs, including some nice long rag chews, and 68 countries in just shy of 3 weeks. A couple of locals are using the same design as their primary antenna for 160 & 80 meters. I got my "un-un" from Balun Designs, and they also have a chart on their website with some suggested wire lengths. Best of luck es 73 de Dave - K9FN On Tue, Jan 31, 2017 at 10:05 AM, Joe Subich, W4TV <li...@subich.com> wrote: > > On 1/31/2017 3:43 AM, Thomas Horsten wrote: > >> Depends on your random wire and what band(s) you want to use. For >> some bands the 9:1 "balun" (not used as a true balun in this case, >> since both the coax and the random wire are unbalanced by nature) >> will step the feedpoint impedance down to something that's a better >> match for the 50 ohm coax, limiting coax losses. >> > > Unless one is using a matching device designed as a current balun, > the common 4:1 and 9:1 "baluns" are actually simple auto-transformers. > > The best approach is an auto-transformer at the feedpoint (with a > counterpoise) followed by a true 1:1 current balun (common mode > choke). > > The 9:1 "balun"/transformer may be more appropriate if the "wire" > approaches a half wave on the frequencies of interest. However, > there is a definite interaction among antenna length, transformer > ratio, feedline impedance and feedline length. > > 73, > > ... Joe, W4TV > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to dpbu...@gmail.com > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
