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@myfairpoint.net
> To: topband@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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