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Re: [TowerTalk] Coax, conduit and toroids

Subject: Re: [TowerTalk] Coax, conduit and toroids
From: Jim Brown <>
Date: Tue, 26 Jun 2012 18:23:49 -0700
List-post: <">>
On 6/26/2012 5:30 PM, Rick Kiessig wrote:
> Is it a good idea to create a coil of coax in or near the base of the 
> tower,run through ferrite toroids?

At a minimum there should be multi-turn ferrite chokes right at the 
antenna feedpoint, using my Choke Cookbook as a guide for winding them. 
As Roger has suggested, an additional choke further down the feedline 
can break up the common mode circuit, acting like an "egg insulator" 
does on a guy wire. I would start with the first one at the feedpoint 
and add others if needed.

Roger has also given you good advice on bonding the shield at top and 
bottom, and on the coax. It's worth "doing the sums" to compute feedline 
loss with various options, but also to consider how well various cable 
types hold up over time.

73, Jim K9YC

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