Topband: CAT5 twisted pair

[James Rodenkirch]

 Bruce and Jim: I will have 9:1 transformers at both ends of the antenna (going to make it "switchable" for east and west directivity) as well as a 2:1 transformer just prior to the input to the shack.
 
Won't bury the cable - run it "above the rocks" at 2 to 3 feet above the lousy ground we have around here in s/w Utah.
 
Appreciate the insight !!!  72, Jim Rodenkirch K9JWV
 


 
> From: k1fz at myfairpoint.net
> To: topband at contesting.com
> Date: Mon, 12 Aug 2013 15:00:32 -0700
> Subject: Topband:  CAT5 twisted pair
> 
> It is working well, and possibly because it is buried except a short 
> distance at both ends.  I was avoiding burying a non shielded, twisted pair 
> with possible varying losses due to
> changing ground conditions.
> 
> 73
> Bruce-K1FZ
> 
> 
> 
>  On 8/12/2013 1:42 PM, Bruce wrote:
>  I am using a twisted  pair, with shield,  that is near  55 ohm
>  impedance for
>  my receiving delta loop. The cable is designed for audio,
> 
>  Depending on the nature of that cable, you're probably better off
>  without the shield if both ends are transformer-isolated as I described.
>  There are two potential problems. First, the shield provides a lovely
>  path for common mode current, which can couple noise via Pin One
>  Problems to a rig. Second, if the cable shield is foil plus drain wire
>  ("rack wire" like Belden 8451), shield current will be STRONGLY coupled
>  to the twisted pair by a mechanism that Neil Muncy named
>  "shield-current-induced noise" (SCIN). The mechanism is that the drain
>  wire has the same lay as the signal pair, and is manufactured so that it
>  is much closer to one conductor the pair than the other. This results in
>  more inductive coupling to the closer conductor, converting the common
>  mode current to a differential voltage.
> 
>  73, Jim K9YC
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