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

Building the popular 9:1 unun antenna based on the popular EARCHI antenna design. An antenna that works relatively well with an internal tuner for 40-6 meters.

A popular antenna for portable ham radio operations or even multi - band operation at home. Assembled this one for less than $20, but it can probably be done cheaper if you have existing parts/container.

Toroids can be found at hamfests, online retailers (Amazon, Palomar Engineers, eBay, etc), and many other sources. Plastic enclosures can be found online as well. Our local Frys carries the plastic/metal enclosure for electronics projects. Save yourself a few dollars and build one of these popular multiband antennas!





73
K5ACL

 

I have done the same thing ,it was nice of them to post the bill of materials and assembly instructions, we did it as a club project many were made, and used on field day . If you lengthen the wire you can tune up a couple more bands. Good job 73 de KD9AUY Stan

 

Where is the B/M?

Clayton N4EV

 

Just received a balun kit from The Wireman. I was expecting a completed one but I guess I should shop with my glasses on. I was trying to figure out how to build in a section of PVC pipe. Think I will go with the square enclosure like you did but use a different mount and eye bolts to attach dipole legs. Good video. It was most helpful!

Cheers Mate,
Elmer N5EKF

 

bruce beckett with maple leaf studios builds a 250 watt baun in 1 1/2 pvc pipe with caps on each end. mine has 117 ft. #14 wire and tunes 160-10 with internal tuner

 

Nice QRZ profile. I enjoyed reading your information. I think citizen band frequencies were very popular in the 70's, hihi. 73

 

It is the left red wire to the antenna terminal?? The right one you already shorted with left black ??

 

Several years ago, our club, KOANT, built similar units as a project. We used 29 feet of wire
for a radiating element and no counterpoise, relying on the feed-line shield common mode.
With this antenna, usually in "field day" conditions, we have worked all continents. I have
over 100 QSO's using 2.5-5 watts on my FT-817. I have no difficulty tuning 6-40 meters
with a Z-817. I am building a second UNUN with a 59 foot radiating element for the 80
meter band. Surprising, it really works well and is ideal for QRP outdoor events.

 

I still keep an EARCHI wire in the car. Had extensive success with this type of antenna in the early days, but found it only works well as a vertical. It is considerably down on a 1/4 vertical, as one might expect given its convenient single wire design (which, in turn, is its 'strength') As a horizontal or sloper, and even with lots of ground gain, I found it quite poor. You can get a -30dB S/N report on WSPR to some distant shore, but whether that makes the antenna useful in practice is another question.

Overall, whilst it's a fine multi-band solution at essentially zero cost, it's certainly a compromise antenna. That is very different from saying it is not worth trying.

 

Thanks all. My next video will be on experimenting with a 'multi-ratio' balun from Palomar Engineers called the 'CUBE' a 2.25:1, 4:1 & 9:1 unun. Interested in showcasing the analyzer results by switching between the different ratios!

Love building these little guys!

 

Excellent video!

 

I've got 2 of these, and one of them is wound with #10 solid-core around a big donut for QRO. Great solution for random wires!

 

I've got a QRO kit waiting to be built that Amazon carried, of all places!

https://www.amazon.com/KiloWatt-Ant...8&qid=1504290083&sr=8-1&keywords=balun+toroid

 

I may have got my left mixed up with right there, but hopefully show where the wires go?

 

You need to be careful with toroid selection. For instance, the toroid used in the EARCHI unit is iron powder not a ferrite mix and consequently requires many more turns to achieve the correct transformation. If you were to use say a mix 43, then the number of turns required would be less. A good example is our model 9130 which uses a low loss ferrite and only requires 5 turns to achieve ideal transformation across the entire HF spectrum.

Bob KZ5R, Balun Designs LLC