Gene Fuller wrote:
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?

I'm not sure myself, Gene. I've wound single core 4:1's, I've bought at
least 2 of them. I've also been told variously they don't work, and
can't even be made.

Just what IS happening here?

- 73 de Mike KB3EIA -