Last edited: 27.02.2026

I am started to make a new balun for the FD4 antenna.

It is based on an article in the Struer OZ3EDR ham group, december 2019 page 30-39. Find a it here, it is in danish, written by OZ1DCZ, Carsten.

Here are very useful You tube video from TRX bench Part 1, #100, explaining this in very detail (very long 52 min).
He explaines about common mode rejection of a balun and how to measure this.

Here is the second part of his Youtube videos. TRX lab #101.
This shows the construction of the Common mode balun.

Here is the 3rd part of this series of Youtube video.
Balun part 3 #105. Here the construction of the 1 :4 balun is shown.