By the way, the reason I think this issue is important is Sevik claims
two transmission line baluns (excited as real transmission lines, not
as isolation transformers) makes a good single core current balun. Not
only are people doing that for themselves, commercial people (like MFJ)
have copied the idea. They then advertise a single corev TL 4:1 balun
as a "4:1 current balun" to consumers.

It seems once something gets into print, it is accepted as fact even
when incorrect.

I'd like to clarify Sevik used transmission line mode, not transformer
mode coupling, in his single core 4:1 current balun. My contention is
it is impossible to build a 4:1 current balun on a single core unless
it is a primary-secondary isolation transformer, and an isolation
transformer would be a very limited performance balun compared to a
properly constructed transmission line balun.

73 Tom