Dave, KI4PSR gave an informative talk on Chokes, Baluns and Ununs at the November Chew & Chat.
His talk covers some of the history of transmission line transformers leading to the development of baluns, ununs and choke baluns as well as definitions and theory. Some discussion on chosing the right balun included ideas on measuring common mode current, consequences of high- vs. low-power wiring, misconceptions about ratios, use of ladder line with baluns and grounding. Finally Dave walked us through a number of examples based on different antenna configurations including some being used by WCARES members.
If you missed the presentation or just want to review, Dave has provided his slides and text; You can find PDF copies at the following links: