[RFI] routers & wall warts

[Jim Brown]

On Sat, 4 Dec 2004 12:20:17 -0500, Jim Jarvis wrote:

>So, I had concluded that it was 10baseT ethernet signals radiating which
>were the source of the problem.

Your conclusions are in agreement with mine that this is the dominant mechanism 
for the best behaved products.  Some products may also radiate directly due to a 
combination of poor circuit layout and poor shielding, and, as noted, the power 
supply can be a bad guy. 

It's the old story of peeling the onion -- you get rid of one bunch of noise, and you 
now hear what is lurking below it, so the search begins anew. 

Some frequencies that are definitely associated with 10BaseT traffic (and they 
occur on 100BaseT systems) are 14,030 and 21,052.  There are also some on 30 
meters and the low end of 10 meters. All of these will be radiated common mode 
from the Ethernet cable if given the opportunity. 


Jim Brown  K9YC