On 9/12/2010 7:50 PM, Owen Duffy wrote:
... Yet I have seen commercial sites
selling a Guanella 4:1 current balun on a single core, arguing that
Sevick said it was ok in a certain context... a context that is unlikely
to ever exist in an antenna system. But hey, Sevick is Mr Baluns, so they
sell. That context relates to another dimension of the balanced /
symmetric issue.

Back to the Carolina Windom, a common explanation holds that there is
common mode current on the feedline between the dipole feedpoint and the
'isolator'. The notion that common mode current exists on one side of the
isolator and not on the other is an interesting one, one better explained
by advertising hyperbole than radiocommunications theory.

Owen

The first part, above, implies that no one has ever constructed such a
balun(s), one on a single core, one on a dual core, used "balanced"
resistances, to serve as loads, then unbalance the loads, and observe
results. I have, when constructed properly, one can be constructed on a
single core. Is the dual core better? Yes ... is it possible to run
the single core balun in conditions where it will fail miserably?; Yes.
Is it possible to run the dual core balun in conditions where it will
fail miserably?; Yes.

As to the second part, I have found a properly constructed balun to be
both, a choke and "impedance-transformer." Indeed, an excellent balun
is optimized to take advantage of both phenomenon.

And, of course, I have found and believe a 160m to 10m balun/unun is
stretching things, probably beyond what one should (but, hey, you can
get by with it), two baluns, a high freq and a low freq are better to
cover such a span ... however, you can carry that to an extreme and
optimize core material/size and windings for each specific band ...

And, radio is an onion, each layer built on a preceding layer. At the
core of all this is the EM transmission theory, and RF is both particles
and waves ... obviously, both have great difficulty being true at the
same time, so "waves of bullets" becomes the explanation ... obviously,
great difficulty is going to be had in having cement solid theory in the
outer layers of this onion. By the time you get to "balance" the errors
are only magnified ... balance is like any balance in life ... you'll
know it when you have it, and benefit from it.

Regards,
JS