[TowerTalk] TH7 SWR trouble ... Coax balun question

[Greg Gobleman]

>This antenna was designed to be used with the
> BN86 balun (BN4000 is also ok) and the conductors supplied with with the
> antenna. The wires are spaced a few inches apart as they leave the balun
and
> connect to the driven element. The spacing and wire diameter is such that
a
> short transmission line of a few hundred ohms is formed by these wires. If
> you run the numbers through a transmission line program (or Smith chart)
you
> will see a surprising shift in the feedpoint resistance especially on 10
> meters.

Chances are, this is the very reason my Telrex TB6EM is way off on 10m.
Resonance is in the CB band and a minor dip in the FM repeater subband.  The
original Balun was a roll of RG8 in a box with a 'compensating coil'?? of
maybe 16ga wire.  I simply used 8 turns of RG213.  I will try a homebrew
W1JR type Balun next time it's down.

73
Greg K9ZM



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