Topband: Beverages Noise

[ZR]

----- Original Message ----- 
From: "Jim Brown" <jim at audiosystemsgroup.com>
To: <topband at contesting.com>
Sent: Tuesday, January 31, 2012 11:51 AM
Subject: Re: Topband: Beverages Noise


On 1/30/2012 5:33 PM, Silvio M. Martín LW9EOC wrote:
> As I can remove noise entering through the ground? and how to isolate the 
> shield?

A common mode choke, made by winding many turns of the coax around a
ferrite core, would help.  The best core to use is Fair-Rite mix #31,
and you want at least 14 turns through a 2.4-inch outer diameter toroid
for 160M.  7-9 turns through a big one-inch inner diameter clamp-on will
work.

** A good feedline only ground rod that is completely isolated from the 
Beverage transformers antenna winding ground rod by 5-10 meters should be 
the first step.
ON4UN's latest revisions go thru this in detail.

The ferrite is useful for minimizing any common mode that remains.

Carl
KM1H