Topband: CAT5 for Flag Antenna Feedline ?

[ZR]

Would shielded CAT5 be useable as a Beverage feed? It would be easy enough 
to match with a binocular core at both ends and I just happen to have about 
300' doing nothing.

Carl
KM1H



----- Original Message ----- 
From: "Jim Brown" <jim at audiosystemsgroup.com>
To: <topband at contesting.com>
Sent: Monday, September 09, 2013 2:12 AM
Subject: Re: Topband: CAT5 for Flag Antenna Feedline ?


> On 9/8/2013 10:30 PM, Bob K6UJ wrote:
>> I got the impression from the post
>> that CAT5 is immune to common mode noise.
>
> I've not heard that, nor can I think of a theoretical basis for saying so. 
> CAT5 is very good twisted pair, with a high twist ratio, Zo = 100 ohms, 
> and its loss is low enough to make it work fine on 160M.  The primary 
> advantage of twisted pair is that it rejects DIFFERENTIAL mode noise. 
> Rejection is greatest when both ends of the line are balanced.
>
> One possible source of your confusion may be reading, but not fully 
> understanding, my work, and Neil Muncy's work, on SCIN, whereby certain 
> deficiencies in the construction of a cable shield convert common mode 
> current to a differential voltage on the signal pair. I have on several 
> occasions observed that high quality unshielded twisted pair, like 
> CAT5/6/7, would have much better noise rejection than that sort of cable. 
> Read about it in several tech papers and tutorials on my website. No need 
> to burden the list with it.
>
> 73, Jim K9YC
>
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