"Danny Richardson" wrote in message
...

I would be far more concerned as to what its common mode impedance is.
From what you describe it sounds like a voltage balun and those
generally have a poor common (blocking) mode impedance.

Danny, K6MHE


I would guess that you are right Danny and this is a voltage balun. I dug
it out as I have recently moved to a flat in the centre of town 100 yards
from a large telephone exchange and surrounded by noise sources. My old
trusty vertical is giving me so much noise here that I want to put up a
balanced antenna in the hope that this will reduce the interference. To
minimise this noise I need a well balanced system. I already have coax up
to the roof and balanced line would be difficult to route so am planning to
fit a balun either at the dipole centre or a few feet below with a short
balanced feed. I dug this balun out as it looked like it would give good
balance. I have another (current) balun which has a simpler bifilar
winding. I'm not sure which will be best for my application. Incidentally
I only run QRP so efficiency is a major factor. I also considered a folded
dipole using 600 ohm line as that would be less prone to static noise but
would then have to look at a 4:1 design.

73 de Dick G4BBH