[RFI] Ethernet RFI Elimination?

[Jim Brown]

>What other frequencies will I hear the Ethernet (I believe Jim's posting
>stops at 10 MHz)?  
>
>What can I do to lower/eliminate the RFI?  The router is about 20 feet
>away from the radio, the shack computer, cable modem and local printer
>are within 3 feet of the radio. 

Hi Eric -- sorry for the late response -- I've been on the road. 

14,030, 21,052, and the bottom 20 kHz of 10 meters are some that I have 
identified.

Shielded CAT5 is NOT necessary, and will probably not be a part of the solution. 
What has worked pretty well for me for the portion of the noise radiated by wiring is 
multiple turn ferrite chokes. 3-4 turns around a #43 ought to make a good dent, and 
it ought to be close to at least one end of the cable. In general, any ferrite large 
enough to pass the ethernet cable through enough turns will likely give decent 
attenuation. Since both ends of the cable transmit, you will likely need chokes on 
both ends of electrically long (> 1/10 wavelength) cables. This is nearly all common 
mode, so shielding is far less likely to be of help.  

As others have noted, a comparable choke on the power line can be helpful. 

If you've done all of this and you still hear this stuff, there are two strong 
possibilities. First, there may be direct radiation from your unshielded 
hub/router/switch. To figure that out, kill power to it. That should stop all traffic 
passing through it.  If there's anything left, it's coming from your neighbors.  I've 
gotten my gear down pretty low, but I hear several of my neighbors. 

Jim K9YC