[RFI] RF getting into 4-port wirelss router.

[Jim Brown]

On Mon,1/12/2015 12:56 PM, Kenneth G. Gordon wrote:
> Ah, HA!!!! I have been hearing a very strong carrier, slightly modulated, on
> 14.030, and 21.063 for years and had never, ever thought it might be RF
> from the network!!!!

If you have neighbors, it's quite normal to hear them too. When I lived 
in Chicago, I heard at least three carriers most of the time. These are 
locked to a clock in the router, each neighbor will be on a slightly 
different frequency. To identify yours, kill power to the router/switch 
and note which one goes away.

6 turns on a #31 or #43 2.3-in o.d. toroid is about right to choke those 
carriers up to 10M, but you'll want 14 turns on a #31 to choke 160M and 
80M, and it will still be effective on 40M.

Note that chokes can't help for interference that is coupled to internal 
wiring of the router due to poor shielding or poor circuit layout, but 
they will kill the common mode stuff coming in on the antennas (cables).

I've written extensively about this in k9yc.com/RFI-Ham.pdf.  Lots of 
conceptual discussion, lots of specific advice for different kinds of RFI.

73, Jim K9YC