Ferrite Baluns

A balun is often used in amateurs radio stations to couple unbalanced equipment (such as transceivers) to balanced loads (such as a doublet antenna fed with open wire transmission line.

At the shack end, the doublet has been tuned successfully on 10 - 80 m using the classic 'Z Match' balanced antenna tuning unit (ATU) for all bands. 

More recently, I have been experimenting with baluns and the use of ATUs installed between the balun and the transmitter (and transmitters having built-in automatic ATUs).  This has resulted in very encouraging results on all bands between 6 m and 80 m.