[Elecraft] Balun loss

[Stuart Rohre]

Well said Ron on the issues feedline coupling to antenna and feedline
radiation.

Back in the old tube days, when every transmitter had adjustable tank
circuits for coupling to an antenna such as the Pi Net, we often used no
balun to feed our dipoles with coax, or to couple balanced line to the
unbalanced Pi Net output coax connector.
The availability of ferrite and iron cores later on, needed a market for the
products and that is when the use of a feedpoint balun became popularized.

However, if you live in a high noise area, you probably do want to mitigate
induction of noise from the outside of the shield pick up to the inner
shield path to the receiver.   Interestingly, I have not seen an article in
the ham press showing any reduction in received power line noise by using a
balun or not at the feedpoint.  The closest, is the observation by Lew
McCoy,  about the apparent "waveguide beyond cutoff" noise filtering effect
upon the Gap antennas because the offset feedpoint is fed with coax run
inside, and shielded by the lower tubing element of that vertical.  That was
part of his review of the Gap asymmetrical fed verticals in CQ some years
ago and available on the Gap web site.
73,
Stuart
K5KVH