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Topband: Beverage feed line...too long?

To: topband@contesting.com
Subject: Topband: Beverage feed line...too long?
From: Dennis OConnor <ad4hk2004@yahoo.com>
Date: Tue, 18 Sep 2007 05:26:43 -0700 (PDT)
List-post: <mailto:topband@contesting.com>
Alessio,
   
  Yes, the Beverage can have a surprising noise level, but the ratio of signal 
to noise will be improved... I sometimes have to reduce my RF gain when 
listening to the Beverage...
   
  What transformer design are you using at the Beverage?
  Is your coax  shield ungrounded at the beverage end? 
  (must be ungrounded to prevent the coax acting as a longwire antenna)
  What kind of ground is under the Beverage?
  (high conductivity soil will not work well with a Beverage)
  Does the Beverage pass close to metal structures?
  (coupling noise onto the antenna / distorting the pattern)
  Do any of the ground radials run parallel to the Beverage wire above them?
  (not good)
  Does your Beverage terminate straight down at each end?
  <sloping terminations can cause problems>
   
  You can choke the feedline at 1/8 or 1/4 wave from the Beverage to further 
suppress it from acting as an antenna...  I would simply use a coil of coax as 
the choke, but you can get as fancy as you like... 
  As a last resort, at the choke point , you can remove a short section of the 
outer insulation on the coax and clamp some ground radials to the braid... Do 
this on the Beverage end of the choke....
   
  And, is there a reason for the RG58?
  (many of us have find RG6 good for Beverage feedlines)
   
  denny / k8do

       
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