[Elecraft] 9:1 Balun

[David Bunte]

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 <lists at 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
>
>
>
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