In message
,
Leon writes
On 24 Jun, 03:18, Nick wrote:
Hi All,

* I keep reading on various websites and in various documents that HF
verticals should have a "line isolator" (a choke/current balun)
located near the antenna's feedpoint to prevent coax feedline re-
radiation, disruption of the antenna's radiation pattern, sub-optimal
vertical performance, and RFI in the shack. *My question is this: just
how important is a choke balun when using a ground-mounted HF (for
40M) quarter-wave vertical antenna with 32 quarter-wave buried
radials? *And if it is important, why wouldn't the choke be placed at
the shack's input, so that the coax's outer shield could act as
another radial? (I had always assumed that a vertical didn't need a
balun at all, and that only dipoles used them. *Am I wrong about
this?).

Thanks!

Nick

A balun isn't required.

Leon

With this type of antenna, it certainly is not common practice to
choke/isolate the coax, especially the coax braid can be grounded at the
antenna feedpoint and in the shack, and possibly at some intermediate
points along its length. It wouldn't do any harm to use one, but it
probably wouldn't do very much.
--
Ian