[Elecraft] Balun Questions

[Brett Howard]

Ok I was referring to a design that was using one core to make a
4:1...  I think the caveat that was being used was that they felt they
could do this and be safe enough with it still being a balun as long
as the load was floating (but I'm not 100% sure thats really the
case)...

So is a multi aperture core good enough for that or would two toroids
be a better idea?

~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
>