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.
I decided to build an air core balun in hopes of saving myself the
expense of buying several torrid cores. The problem is none of the
plans listed in the Bill Orr handbook or that I have found on the
Internet actually work. On my one commercial 4:1 balun if I place a
200 ohms resistor across the leads of the balun I get an SWR reading
of about 1.1:1. When I build the air core balun listed in the William
Orr handbook I get a 2.5:1 SWR.
Hmm..So I decided to try some 4:1 air core balun designs off of the
Internet as well. I found the web page below;

"A 4:1 Air-wound Balun"
http://combotec.com/projects/balun14/balun14.html

I built the balun exactly like the web page described. It does not
work. 2.5+ SWR on 10 meters with a 200 ohm resistor plugged up to the
terminals. The same 200 ohm resistor shows close to a 1.1 on a
ferrite 4:1 balun.

So, the Bill Orr 4:1 air core balun listed in his handbook does not
work on 10 meters. Neither does his 1:1 air core balun when tested on
10 meters with a 50 ohm resistor. The 4:1 air core balun listed on the
web page above does not work either. I'm getting tired of building
air core baluns that don't work.

So....,does anyone have any plans for a 4:1 air core balun for feeding
450 ladder from a tuner that you have actually tested and used that
and it shows close to a 1.1:a SWR when presented with a 200 ohm load?

By the way, of the 4 or 5 1:1 commercial baluns I purchased back in
the 1990s only one of them actually shows a 1.1:SWR when presented
with a 50 ohm load. The others show between a 1.7:1 and 2.1:1 SWR on
10 meters, and that is among several baluns that were all the same
model from the same manufacturer. I'd post the brand name, but the
paper brand labels wore off years ago. I can tell you it has little
brass machined screws and brass holders on the sides of the balun and
not the piece of copper wire coming out to the eye hooks. They are
enclosed inside the typical white PVC pipe with caps on each end and a
coax connector at the bottom.

Michael Rawls
KS4HY