[RFI] ebay line filters

[Jim Brown]

On Mon,8/15/2016 5:39 PM, KD7JYK DM09 wrote:
> The results were disastrous!  Massive amounts of RFI blasted from every inch
> of the cord and most of the wiring in the shop where none had existed before
> regardless of the filters used.  I asked on this list how this could be.  No
> response.

I missed that post, but I'll respond now. The reason is VERY simple. The 
noise is NOT a differential signal, so filters don't work to kill it. It 
is a COMMON MODE signal, which causes common mode current on the AC 
line, so you need a COMMON MODE CHOKE to kill the current. The current 
makes the power cable as a transmitting antenna.  I just posted that in 
a response to Doug, which I don't think he understood. I posted a link 
to a tutorial that includes specific recommendations for winding turns 
around  a #31 ferrite core to form the common mode choke. I also posted 
a link to a slide show that includes a photo of a suitable choke. I 
suggest that you take a look at that email and both links.

73, Jim K9YC