[TowerTalk] 40M rotary dipole and CM current

[john at kk9a.com]

I remember the biting mic/radio days. I had that happen on an expedition to
Antigua in the early 80's using a very low beam with no balun. It is
obviously a good practice to put a choke at the antenna. I have one on every
antenna. Is there benefit to also putting a choke near the station entrance?


John KK9A

To:	towertalk at contesting.com
Subject:	Re: [TowerTalk] 40M rotary dipole and CM current
From:	"Joe Subich, W4TV" <lists at subich.com>
Date:	Thu, 21 Sep 2017 21:07:45 -0400
List-post:	<mailto:towertalk at contesting.com>

By suppressing common mode current in TX you prevent the "random radial"
phenomenon.  In doing so, you mitigate the "pin 1" problem by reducing
the RF voltage on equipment cases/connecting cables and avoid issues
of a "biting mic" (if you're old enough to remember RF burns to the lips
from the case of a D-104).

73,

   ... Joe, W4TV