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TopBand: Common mode isolation

To: <topband@contesting.com>
Subject: TopBand: Common mode isolation
From: w7iuv@axtek.com (Larry Molitor)
Date: Tue, 15 Sep 1998 23:32:20 +0100
At 07:39 9/15/98 +0200, Greg, ZS5K wrote:
>      Would anyone  like to comment on whether the same argument would hold
>true for  EWE's?  

Greg,

I'm not sure that the exact same problem occurs on most unbalanced antennas
such as the EWE and Beverages. However, in my experience, the same solution
is valid for the problem that does seem to occur.

I found that on my "underground" beverages, I had a similar problem. After
investigating, I came to the conclusion that I had a ground loop occuring
in the coax shield. Using the same transformer construction as I did for
the pennant, I floated the shield connection at the antenna end of the
line. I.E. coax goes to the primary, antenna and ground to the secondary,
no local ground to the coax.

This did not help the F/B of my poor unterminated buried Beverages a bit,
but it did reduce the power line noise and computer birdies a bunch!

Look back in the archives a few days, W8JI discussed this effect quite well.

73,

Larry - W7IUV



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