Build your own 9:1 unun antenna on the cheap!

If you guys look at some of the models here, you'll see the quality difference between this brand and many others.
Personally, I have seen the guts of most of brands and ONLY use Balun Designs.
Brian

http://www.balundesigns.com/ununs-for-end-fed-antennas/

 

I enjoy Bob's Baluns immensely.... Below is the OCF dipole I have currently deployed at home.

 

I built one several years ago with an SO239 Chassis mount for the antenna connection. I built it originally for my go bag but due to my current operating position and the lack of room I am currently using it now with a 50' wire as an inverted L. Much better results than I expected. If someone is thinking about building one, they don't cost much and it's definitely great to have laying around because you never know when you may need it. Have a good weekend all and 73 De Jesse - W4JRQ.

 

Wait! Where are the all of the theory, modeling and EZNEC freaks who will say that these things can't work or are too inefficient or whatever?

 

Oh, how I hate videos! Instead of writing articles and preparing drawings the authors come with ... a video. You have to watch carefully, spend boring ~10 minutes making your own drawings and a couple of notes before starting your project. Possibly you have to watch this boring thing several times to learn where you should make a pause to get time enough to draw a sketch. I am happy that I don't need this one as well as most of things "described" in other videos!

73,
Martin, OK1RR

 

Nicely done presentation. Thank you for sharing. Ununs and Baluns are great projects and can save a ham a great deal of money in spinning their own. Build, don't buy...

 

The freaks would be right in saying so.
Almost everything 'works' if your willing to accept losses.

Losses are hard to spot , and often Hams operate far less than ideal systems and may even think it rocks.

When contacts are not as solid as they wish for , Hams will then blame the poor propagation.


gregW OH2FFY

 

Good stuff, i use a similar concept with 14 guage wire and a manual tuner and it's opened up all kinds of doors, especially on lower bands. Hope to blog on it sometime but too busy using the antennas
73 and gud DX.

 

I made a 9:1 UnUn using a couple of ferrite cores designed to go over a section of RG-8 with 9-turn of hookup wire following the pattern used in the EACHI design. The image shows the dimensions. With it, I can use it without a tuner from 160M to 6M but there is a big thing here: You have to be careful how you dress the feedline.

When I dressed the feedline straight down from the UnUn, the SWR was not good and the lower two HF bands were unusable. The feedline dressing is critical, in fact. Then I dressed it down under the "counterpoise" bisecting the vertical and the horizontal, approximately hanging down 45-degress from the counterpoise. I also included a 1:1 Balun that uses ferrite beads and this was enough to make the antenna usable all across the HF bands plus 6M. While the SWR is less than 2:1 all across the bands, I still use the FT-450's internal tuner to finesse the system.

The wire used is #14 house wire for the 16-ft counterpoise and #14 copper clad iron wire for the 53-ft section. The 20-ft of feedline connected between the 1:1 Balun and the 9:1 UnUn is composed of an 18-ft RG-8X line which is connected to a 2-ft RG-58 pigtail coming out of the UnUn. The feedline to the shack is RG-8.

One other consideration is that it is isolated from any surrounding metal objects. If not done this way, the SWR may well be affected.

Note that I also have experimented with wirewound trifilar wound coils on 1-1/4 inch sections of PVC pipe and while they worked, they were best between 80M and 12M, the other bands were not very good. While the PVC ununs work, the ununs wound on ferrite cores seem to be more desirable.