[RFI] Ethernet, radio astronomy, and electric fences

[Jim Brown]

On Fri, 28 May 2004 12:01:36 -0400, Martin Ewing wrote:

>Folks,
>
>Fraser Robertson, G4BJM, kindly supplied some real Ethernet spectrum 
>measurements which I've posted at my  RFI web page -- 
>www.aa6e.net/aa6e/rfi .

Is a significant component of the Ethernet stuff common mode?  If so, it
seems that common mode chokes should help, especially with MF and HF. These
pictures strongly suggest that Ethernet may be a big part of what is causing
me grief on 160!  

The tricky part here is that the commonly used type 43 materials that are so
effective at 30 MHz and above don't do much at HF and MF. An effective choke
will probably  need  to use a different material.  On the other hand, winding
many turns around a #43 toroid will lower the peak frequency significantly.
Looks like a nice area for some research!

Jim Brown K9YC