Continuing with our ‘dirty’ theme, today we will take a look at a ‘dirty’ balun. These are also known as ‘ugly’ baluns.

This low-cost, effective and extremely easy to build balun can be used with your 20m / 40m ‘dirty’ dipole. These are also especially effective with a G5RV type antenna.

OK, some people will argue that this isn’t a true 1:1 balun, but rather a coaxial choke. Well either way it does the job that is required!

After installing my dipole, I noticed that I had an excess of the 50 ohm coax feedline.

Usually, if I have an excess of 20 feet or so I often wind the coax at the antenna connection end into a 9 or turn loop held neatly and flat by electrical tape.

A 1.5 litre plastic carbonated drink bottle used as a former is excellent.

Dirty Balun“Ugly Balun” by DAVE THOMAS, M3RUH

But remember to always hang the bottom side upwards for obvious reasons!! (For those who find it less obvious, rain/moisture can get into the open end, so we need to point it downwards.)

This acts as a simple balun and also stops rf from returning back down the outside of the coax braid to the antenna tuner.

As these baluns can add weight to your dipole, you may want to place it rather at the base of your mast.

The more adventurous often add a second ‘dirty’ balun in the shack as well.

The purists out there do point out that:

* It’s sound engineering practice to fit a 1:1 current balun at the feedpoint.

* Baluns constructed from coiled coax are narrow-band and need careful design to place maximum choking impedance at your operating frequency.

* Baluns constructed from coiled coax will be predominantly reactive away from their self-resonant frequency. That means they can actually exacerbate common-mode current problems in some installations.

I say that if it gets rid of unwanted rf floating around, stops TVI and helps us get a better signal out, then it is good to me!

See other examples of ‘dirty’ balun construction HERE

Some video examples:

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