W2AU 4:1 Ladder-Line Transition Balun 

Long the standard of the industry the W2AU baluns are built to last!

The W2AU is the preferred Balun of Amateurs worldwide.

W2AU’s operate at a low VSWR from 1.8 to 40 mHz, and handle powers up to 2 KW PEP (at SWRs of less than 3:1).

W2AU Baluns are transformer designs with ferrite cores to provide 95% minimum coupling efficiency. Each has a built-in lightning arrestor, and 600 lbs of pull-apart strength in a weatherized, rugged package using only stainless steel hardware and quality materials.


Since many Hams are the inventive types, it should noted that they also tend to not read the instructions and succeed in achieving their goals.

In any event, the matchbox is a tuner and all it does is make the transmitter believe it has an antenna with a lower SWR than it really has. This way it will introduce more power to the antenna than it can typically radiate.

A random length antenna, one not tuned to any one frequency is a compromise antenna. Anywhere it is not resonant it will produce significant SWR’s above 3:1.

With 200 watts of continuous key down CW it would heat up the core of the W2AU balun, at the feed point,and damage it, but that is the extreme example. Many Hams understand this and do it anyway with care.

Also, note that new solid state equipment further limits your operating options never contemplated over 50 years ago when these instructions were made. The equipment manufacturer dictates the parameters of your operating ability.

It is suggested that if using ladderline, no balun, because a balun at the feedpoint, would interfere with the radiation that the offset antenna needs from the ladderline.

Instead use a ” W2AU 4:1 Ladder Line Balun ” at the end of the ladder line transitioning the ladder line to a coax entry into your shack. A 4:1 extends resonances available. Some hams use a 1:1.

These are some ideas in using an offset antenna.

Remember your ABC’s – ALWAYS BE CAREFUL


Current Stock:
W2AU 4:1 Ladder-Line Transition Balun
2.00 LBS
8.00 (in)
1.50 (in)
5.00 (in)
Shipping Cost:
Calculated at Checkout

Reviews Hide Reviews

This Balun lives up to the Unadilla High Standard

Bill N4ooc on 2nd Feb 2016

I purchased this balun to use at the base of a cloapable portable 20-6 meter Vertical. I have tried other brands they just did not cut the mustard, Unadilla did the trick.

Wide band balun.

Ben on 8th Jan 2015

Works well with low SWR and wide band on HF.