Decades ago I had an Atlas 350XL aboard my sailboat. I used the
insulated backstay for a random length vertical with a Drake tuner. My
operating position was the nav station which put my metal hand mike
about 9 ft from the bottom of the insulated backstay. Of course the
antenna started at the output of the coax fed tuner less than 4 ft from
the mike. The 350XL was a 200 watt rig. If I turned it up much past
100 or so watts out on some bands/freqs I would get RF sparks jumping
from the metal mike to my lips.
In defense of the setup... On some bands/freqs I could go full power
without getting zapped. I had a decent ground, the engine, shaft, prop,
and a ton of steel in the water (fin keel.)
Patrick NJ5G
On 9/22/2017 8:06 AM, john@kk9a.com wrote:
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@contesting.com
Subject: Re: [TowerTalk] 40M rotary dipole and CM current
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Thu, 21 Sep 2017 21:07:45 -0400
List-post: <mailto:towertalk@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
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