[Elecraft] Balun Questions

[Brett Howard]

I've heard a lot of really great things about balun designs
products...  And in looking at their 4:1 for dipoles and yagi's it
looks like they are simply doing 2 1:1 baluns on a single core.  Looks
to me like they are even wrapped in the same direction and paralleled
on one side then series on the other end.

http://www.balundesigns.com/servlet/the-56/current-balun-4-cln-1-designs/Detail

However their more general one:
http://www.balundesigns.com/servlet/the-69/4-cln-1-balun/Detail

I can't really trace out how its wired up...

~Brett (N7MG)

On Fri, Jul 23, 2010 at 11:00 AM, Tom W8JI <w8ji at w8ji.com> wrote:
> <<
> This sounds really similar to a lot of plans that I've seen... One
> other piece that I've noticed on many of these that no one seems to
> ever mention is that the two 1:1's are usually wound in opposite
> directions on each half of the core...  I'm assuming this helps to
> reduce the coupling between the two 1:1's?  Also I'd be interested to
> hear people's thoughts on this "improved balun"...  Seems to be an
> attractive solution.  It only pictures the schematic here and I kinda
> picture it as being wound similarly but you wire one of the turns on
> one of the feeds from "out" side to "in" side.  Essentially the ends
> of the wires would fold back over the core to get to its location>>
>
> If you are talking about two cores in the balun, and each core wound with
> half turns and then flipped with a transposed winding, everyone who has
> measured the fancy winding concludes it does nothing overall except move
> things around.
>
> If you are talking about winding two 1:1 baluns on a single common core and
> using that to make a 4:1 current balun, I can guarantee you that will not be
> a balun. It will unbalance any balanced load placed on the balun's balanced
> terminals. Each transmission line transformer has to be on its own
> independent core. They cannot share a common flux path.
>
> 73 Tom
>