[Elecraft] Balun Questions

[Tom W8JI]

<<<Interesting enough his high power one uses two cores and appears to be
made the same as the "budget" one that is wound on one core...  Seems
like stacking them on top of one another is going to just couple them
and hinder your isolation but maybe I'm wrong there....>>>

Hi Bret,

With two toroids spaced with air gap, coupling is much less between the 
transmission lines. The lower the mutual coupling the better behaved the 
balun is into balanced loads or less that perfectly balanced loads. I expect 
two toroids with some air gap between them to be acceptably isolated, 
although it would be best to confirm this.

The budget balun however is a mistake.  It is electrically impossible for 
that balun to feed a real load, like an antenna, with balanced currents. It 
will work just dandy on a single small floating resistor, but that is not a 
balanced load.  A single small floating resitor has no defined balance at 
all, because it has nearly infinite common mode impedance.

I'll have an article out in a week or so, maybe less, that explains this all 
in detail.

73 Tom