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Topband: Tower as part of radial system?

To: topband@contesting.com
Subject: Topband: Tower as part of radial system?
From: Charles Bibb <zedkay@bellsouth.net>
Date: Fri, 12 Jan 2007 16:08:57 -0600
List-post: <mailto:topband@contesting.com>
Hi, topbanders

I was out in the yard this afternoon, checking on a few things before the 
storm moves in:

First, I rigged a remote vacuum relay, switchable from the shack, from the 
feed-point of the vertical TX antenna to
ground.  I wanted to see how much noise was being re-radiated for the 
Beverages to deal with.
Happily, it seems that my Beverages are not close enough to the TX antenna 
to pick up any additional
noise, at least when compared to the ambient local noise. My vertical TX 
antenna is not grounded.  It
"floats" above ground and is fed through an L-network. With the TX antenna 
tuned up, I could tell no
difference in received noise on any of the Beverages between TX antenna 
grounded and un-grounded.

My vertical TX antenna runs up parallel to the tower in the same way as the 
vertical portion of an
inverted L does, about three and a half feet away from the tower. There is 
a KT-34XA at the top (90
ft) of the tower. My tower is grounded for lightning protection to several 
ground rods at it's base, but
it is NOT tied in to the ground radial system for the vertical TX 
antenna.  Should it be?

Next, I rigged the relay to attach the tower base to the radial ground 
system.  While, again, I found no
difference in the noise that the Beverages hear, there was a noticeable 
change in SWR of the TX
antenna between adding the tower to the ground radial system and not. The 
change is easily tuned out
by adjusting (remotely) the L-network, so no problem there.

My question is:  Should the tower be part of the radial ground system, or 
not?  Which way introduces
the least amount of loss into the system?

Charles - K5ZK


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