[Elecraft] Elecraft] RFI on K3s

[brian]

Interesting.  Putting one on my dishwasher almost completely silenced 
it. It had been S8.

I'm thinking of adding one to the XYL's treadmill.

73 de Brian/K3KO

On 6/21/2016 16:42 PM, Jim Brown wrote:
> On Tue,6/21/2016 9:22 AM, brian wrote:
>> Nothing has been mentioned on what had been standard practice years ago.
>>
>> That is installing a good RFI filter on the mains right at the station.
>> These filter can knock things down 40 dB in both directions.
>
>
> The reason nothing has been mentioned about it is that it doesn't do
> much to solve RFI problems. That's because MOST RF noise is coupled by
> common mode radiation from systems and common mode reception to systems,
> not by differential mode, and these filters do NOTHING to kill common
> mode current.
>
> The data sheets for commercial filters quote numbers for "common mode"
> suppression, but what the power industry calls common mode is the
> voltage between neutral and the green wire. That's NOT what the rest of
> the world calls common mode, which is a longitudinal current ALONG the
> cable pair, and which causes the cable to radiate (and receive)  like
> any other antenna.
>
> More than five years ago, I bought some good commercial power line
> filters and mounted them in electrical boxes to put in line with the
> output of the Honda 2000i generators that we use for CQP county
> expeditions and Field Day. Those filters did NOTHING to suppress the
> noise. What DID work was a common mode choke formed by winding 4-5 turns
> of the power cable through 5 #31 cores.
>
> 73, Jim K9YC
>
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