Owen wrote:
. . .
This leads me to think that measurement of the imbalance current at a
single point might not give the "big picture". I found scenarios where
inserting an imperfect balun increased the current at a point (it
changed the magnitude of the standing wave and more importantly moved
the current minimum), so I could see someone with a handy-dandy
current probe measuring such a situation and insisting they have proof
the baluns don't "work".

This situation lends itself well to modeling, where it's readily
illustrated. While it's often difficult to exactly model a given
physical setup, modeling allows us to control the variables and clearly
see what's happening. We can often apply this knowledge and insight to
real situations.

Roy Lewallen, W7EL