Topband: FERRITE BEADS

[Tom Rauch]

> How many of these will I need to put over the coax to make an effective
> balun?

It depends on the balun impedance your exact application requires, but the
answer is probably more than you would every care to purchase!

You need to be up around a 65 material at high power high stress
applications, or 73 Materials with modest stress on the balun.

You also need multiple turns through one core window rather than a string of
beads, otherwise the number of cores required on 160 would be pretty high.
An air core choke is a cheap alternative.

> Another question on the same line.
> Several years ago I saw either in a mag or handbook where a current balun
> was made out of steel wool placed over the coax. The steel wool was
> compressed inside a plastic tube with the coax run through the middle.

I called the ARRL's attention to the fact the steel wool does not work at
all. They tested and confirmed it, and removed  that info from the Handbook.
I hope it is still gone. I don't think anyone should laugh at that. It
really isn't a laughing matter when a book like the Handbook or QST gives
useless information to people trying to work on stuff.

73 Tom