"Tom Coates" wrote in message
news
I'm seeking a 4:1 balun design that could handle 10 watts efficiently on
20M and would be easy to reproduce without purchasing special ferrite
cores,
etc.

There's an old design that puts an electrical half wave of coax between
the
two connectors on the balanced side.

What drawbacks does this old design have compared with more modern ones?
Suggestions would be appreciated.

Tom, N3IJ

Hi Tom

If you are interested, I have about 20 new ferrite toroids that arent
marked. I wouldnt mind constructing a couple bifilar, 4:1 baluns and
connecting them back to bact for loss measurement at 14 MHz. If the
prototype works well enough, I could easily measure them at other
frequencies from about 5 MHz to 450 MHz.
The cores are 1.9 inch OD and 1.4 inch ID and 3/8th thick. I'd expect
one toroid to be adequate for power levels around 20 watts. That could
probably be estimated after the loss is measured.

So, if you are interested, I'll give you a couple cores after I make some
measurements on a prototype.

I'd do a little research on web published information before building the
prototypes.

I have build alot of baluns for higher frequencies, but I cant make power
on any band.

Jerry

Again, I am not interested in selling. HAM stuff is my fun time.