I can't say whether it's 4:1 or 1:1, but it fits the description of a
1:1 W2AU balun I got long ago. I think they might have changed the
design somewhere along the line, but the one I have is a voltage balun.
A 1:1 voltage balun measures a short circuit across the two input
terminals or two output terminals; a 1:1 current balun will read open.
If it's a 4:1, it's very likely a voltage balun, but both voltage and
current 4:1 baluns will show a DC short across the terminals. The only
way I know of to determine whether it's a 1:1 or 4:1 is either to use
something like an antenna analyzer, or connect the output to a 50 ohm
dummy load and look at the SWR at the input side. If it's a 4:1 balun,
the SWR will probably be at least 4:1, and likely higher.

Roy Lewallen, W7EL

Buck wrote:
I have been given a W2AU balun. It is an older one with no markings
other than W2AU BALUN on it. I am not sure which model it is, 1:1 or
4:1, but I am guessing it is 4:1.

The balun has a metal bar that goes from the ground screw of the
SO-239 connector to the support eyelet on the top of the balun.

It is 6 inches long with about 1.5 inch diameter tubing. It has three
eyelets, one on top and one on each side of the top for the dipole
wires.


Can anyone confirm what I have here?

thanks