[RFI] ethernet switch with shielded case or low emission spectrum

[Jim Brown]

On 3/29/2018 7:16 AM, Chris wrote:
> That's what I hear as well...birdies spaced evenly across the band(s).  Not s9 or anything like that, but still real annoying!!  I guess that is the price we pay for modern technology.

How is that dish getting its power?  If via the Ethernet cable, my money 
would be on that as the source of these birdies. The wall wart that 
powers it is probably a switch-mode supply, and the Ethernet cable is 
its transmitting antenna.

These are NOT Ethernet birdies -- they are stable, modulated carriers 
around 14,030 kHz, 21,052 kHz the low end of 10M and 6M. There are two 
that show up on 30M. There are probably others, but because I'm a CW op, 
these are the ones I run into. If you have neighbors, you'll hear their 
birdies too, slightly displaced in frequency from your own, because each 
router has its own crystal. The Ethernet cable is the transmitting 
antenna, and electronics at both ends of the cable are the transmitters, 
so both ends need a serious ferrite choke.

If you haven't already done so, take a look at 
http://k9yc.com/KillingReceiveNoise.pdf  which addresses how to identify 
noise sources by type, track them down, and suppress them. Also, NK7Z's 
website has lots of very useful info, including spectrum plots of 
various noise sources. He also shows an excellent method for tracking 
them using a spectrum display running 24 hours!

73, Jim K9YC