RadioBanter - View Single Post - Does anyone have plans for a 4:1 air core balun that actually works?

Owen Duffy · July 2nd 11, 11:24 PM posted to rec.radio.amateur.antenna

Michael wrote in news:e820bd25-b016-45f3-9511-
:

I've been enjoying several Lazy H antenna I built for 10 meters that
are being fed with 450 ohm ladder line back to the tuner. They
antennas are performing well. The problem is the external baluns I am
using back at the tuner heat up even at 100 watts. These are suppose
to be 1.5 kw baluns, but they can't handle the impedance mismatch for
full legal limit. I have commercial 1:1 voltage baluns and 4:1
voltage baluns.

Therein lies a possible explanation of your problems.

If you view the 4:1 voltage balun as device that can transform any load
from say 5+j0 to 5000+j0 (just staying on the X=0 axis) at 1kW (for
round numbers), you expected it to handle 15A, and withstand 3000Vpk,
over more than a decade freqency range, and to have a maximum loss of
say 20W (which is about enough to heat the core in most enclosures to
Curie point) or 98% efficient.... and then give a near ideal impedance
transformation.

Well, it just doesn't happen that easily... as you now know.

Owen