Roy Lewallen wrote:
Hm, I'll have to think about that one a bit. I checked out the Elecraft
info and it appears that the balun is wound on a single binocular core,
not two separate cores. You could make a 4:1 current balun that way if
you could manage to keep the flux from one pair of windings from
coupling to the other, but I don't know right off how you'd do it. I
suspect that some sort of complex winding scheme might make it work. But
if the one you're trying to measure really has two separate cores, I
suspect that measuring the Elecraft might not be a good test of the method.

Roy Lewallen, W7EL

Hi Roy,

I have read your comment about the requirement for two cores for many
years, and I am still puzzled. In the ideal case the balun action is
performed by transmission line transformers, and the flux induced in the
core by the differential current is minimal. The core primarily affects
frequency response and common mode choking action.

According to his books, Jerry Sevick has designed, analyzed, built, and
measured many single core 4:1 current baluns. He never mentions the
problem you allude to.

What is happening here?

73,
Gene
W4SZ