[RFI] RF quiet wired routers

Gene - N0DQS gmitch at iowatelecom.net
Tue Jan 1 01:06:44 EST 2008

On Mon, 31 Dec 2007 19:14:30 -0600, Gene - N0DQS wrote:

>I discovered that it is a bad CAT5 cable or should I say poor,
>cheap or something like that. Unplug that cable and the birdies

Not a bad cable, a bad router. The cable is acting like a long wire
antenna because the router has lousy common mode isolation on the
output that the cable is connected to.

The simple ferrite chokes described in my RFI tutorial will knock
those birdies down a lot by adding a high common mode impedance in
series with the antenna (the Ethernet cable).



Jim Brown K9YC


I replaced that cable and lost the birdies. That cable was a cheap quality 
cable I had picked up someware. No birdies on the router and other cables 
just the one cable and as I said it went away with replacement of that "bad" 
cable. I attempted different combinations of ferrite beads but did not 
resolve the issue.

Happy new year everyone

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