- Those of you that have built a multiband HexBeam will know that one of
the more tedious aspects of the construction is cutting and
terminating the 50 Ohm coax for the band interconnects - particularly
if RG213 is used. Twin-feed would make the job easier, but
commercially available line tends to have a charactersistic impedance
of 300 or 450 Ohm - too high for our application.
So this week I tried constructing a "bespoke", low-impedance,
twin-feed and measuring its RF characteristics. You can see a write-up
on my web site:
"Producing a Zo as low as 50 Ohms is challenging and can only be
achieved by very careful choice of cable type"