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Re: [TowerTalk] Belden 8267

To: towertalk@contesting.com, TOWERTALK@contesting.com
Subject: Re: [TowerTalk] Belden 8267
From: TexasRF@aol.com
Reply-to: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Date: Sun, 25 Apr 2010 11:37:11 EDT
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
If I were a coax manufacturer I would down play the importance of a
non-contaminating jacket as well. Can you say "contamination is our friend  
- fire up the coax machine"?
 
I well remember seeing the black copper shield and dielectric inside Belden 
 8214 coax after being in use a few years. The loss was about 3X the new  
spec.
 
Someone, somewhere, along the line thought non-contaminating jackets were a 
 good idea or there would be none made today.
 
8267 is indeed a non-contaminating RG8 sized coaxial cable with good braid  
coverage and solid PE dielectric. It is tough as nails and can be expected 
to  last a long, long time, even in a flex loop. Yes, the loss is higher 
than the  newer foam cables but for modest run lengths, it certainly has a 
place in many  hf applications.
 
73,
Geald K5GW
 
 
 
In a message dated 4/25/2010 10:04:05 A.M. Central Daylight Time,  
jim@audiosystemsgroup.com writes:

Roger  said,

>It appears to be pretty expensive for what is apparently the  equivalent
>of the old standard coax with a solid PE dielectric, bare  copper
>braid/shield, and 5" bending radius. 

As best I can tell  from the Belden catalog, it's essentially the same as 
8237, but with a  non-contaminating jacket, and a dielectric that gives 
lower loss at UHF  (but both are solid PE). The cost premium at places 
like Markertek (a  broadcast house) is about 22%. Sorry John -- their 
catalog lists only 500  ft and 1,000 ft spools. 

But that brings up an interesting question.  When I talked with Belden 
engineers several years ago, they sort of  downplayed the importance of a 
non-contaminating jacket, saying that all  black PVC was pretty UV 
resistant. If that is true, given that the result  of contamination is a 
degradation of the dielectric, and that loss at HF  and VHF is almost 
entirely copper, should we still CARE about a  non-contaminating jacket on 
cable that will be used only at HF?   

Important note -- I'm not stating this as fact, nor as a request for  
"opinions" or "what you've always heard/read," but as a question to those  
who may have seriously studied this and have real information on the  
topic. 

73,

Jim  K9YC


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