[Elecraft] Balun at input or output of tuner

[Ron D'Eau Claire]

I would avoid coaxial cable in any situation where there can be a large
impedance mismatch because of just the losses mentioned. Even though low
power might not burn up 3 feet of coax, that's still a chunk of power thrown
away.

The ideal CM choke at the OUTPUT of a tuner feeding a balanced line would be
made of open wire line. The old air-core chokes did just that but, to have
the choking impedance needed, they are physically B-I-G, especially if used
on 80 or 160 meters. Some look like 'steampunk' art with huge coils
occupying a whole wall, not unlike what one sees in some photos of early
spark transmitting stations. 

A parallel pair of wires wrapped on suitable toroid cores would be my first
choice today, but never with coax between the choke and the matching
network. With a little ingenuity one can make a very clean, neat open wire
line installation running across a ceiling using small insulators attached
to the ceiling if the operating position is far from the point of egress to
the outside. 

73, 

Ron AC7AC

-----Original Message-----

Dean

Nice analysis of the issues. K9YC also presents baluns done with wire pair
rather than coax, RG213 or otherwise. Might not they be a better solution
than coax when constructing a CM choke for driving windowline?

Jim ab3cv