[Antennas] 4:1 or 1:4?

[Steve L.]

These comments are making me scratch my head, since I
designed and wound Kevin's balun:

> I would get rid of the 4:1 balun first thing, Kevin.
> It is only making bad
> conditions worse. 

> the end of the line due to a high impedance there.
> Your 4:1 balun is just
> making the problem 4 times worse than a 1:1 balun. 

This is a 4:1 step DOWN balun. It takes the high-Z
he's seeing and steps it down 4:1, not UP. The only
problem you'll see is with certain very low-Z inputs
where the 4:1 is definitely not appropriate.

I use four of them in my high-power setup without the
slightest problem, but I DID have to trim the balanced
feedlines to get that 'sweet spot' where no crazy-Z
was presented to the balun's input of course. No balun
will operate way outside it's transmission line would
impedance, unless it's a very low-mu material that
isn't working very well to begin with.

If you want to use the very best balun setup, isolate
your entire transmatch using a non-conductive chassis
and use a 1:1 50Ohm ferrite core current balun on the
transmitter side of the transmatch. This works great
except no commercial matcher does this, you must build
it from scratch yourself and it doesn't work well with
really high-Z loads since there is no impedance
transformation at the balanced side. The balun always
sees it's characteristic impedance on both sides (when
you have the transmatch tuned, of course) so it's
happy at all times and you can use a higher mu ferrite
without worries.

Thanks,
Steve N4SL Machias, WA CN88xa




__________________________________________________
Do You Yahoo!?
Send FREE video emails in Yahoo! Mail!
http://promo.yahoo.com/videomail/