[RFI] Ethernet RFI
jim at audiosystemsgroup.com
Sat Jan 22 22:40:59 EST 2005
On Sat, 22 Jan 2005 21:28:10 -0600, Ford Peterson wrote:
>I'm willing to bet my next paycheck that the noise will be gone
>if they are properly shielded by retaining the 'pairs' in the
You'd better go for a paycheck loan, Ford. :) You (and the tutorial)
are absolutely correct that a twisted pair helps TREMENDOUSLY in
killing DIFFERENTIAL mode coupling to/from the cable. And we have a
lot of experience with loudspeaker cables that says that twisted
pair is FAR superior to parallel wire (zip cord) in minimizing RFI.
But twisting helps NOT AT ALL when the cable is excited COMMON MODE
and radiates as a long wire antenna. That's what the chokes can
reduce (a LOT).
My experience with HF trash from Ethernet cable is that it is all
COMMON MODE radiation from the cable, added (sometimes) to direct
radiation from the box itself.
Jim Brown K9YC
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