Topband: CAT5 twisted pair

[Bruce]

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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