[Elecraft] RFI

[Bill W5WVO]

Tom,

So-called EMI/RFI filters are typically differential-mode devices (i.e., there 
is an L/C  filter in each side of the AC line). Noise generated by switching 
power supplies is, at least in my experience, usually common-mode. Differential 
mode RFI filters won't do a thing for it. Get a big ferrite toroidal core (type 
43 is a good mix) and wrap it fully with the AC line cord close to the machine. 
You will probably find that the noise is eliminated or reduced. If it is reduced 
but not eliminated, put another core in series with the first one, extending the 
line cord if necessary. If your neighbor is willing to continue to help you 
solve the problem, I'd try this before going to a noise phaser, which are a pain 
to adjust every time you switch frequencies.

Bill W5WVO


Don Rasmussen wrote:
> The MFJ-1026 will cure it. You only need a simple external antenna
> near the noise source. Phase that kind of noise out.
>
>
> Cheers,
> Don
>
>
>
> Hi Don
>
> I know what you were going thru as my next door neighbor has a
> Kenmore front-loader (made by Whirlpool, I think) and I hear the RFI
> on my radio and I am 200 feet away from his house and the antenna is
> 400 feet in the backyard from his house. Seems every 15/18KHz or so,
> I hear the hash noise...since I use 30m, it falls on 10.103 and
> 10.118 but is fairly broad so covers up weak signals.
>
> I gave him an EMI/RFI suppressor block but that didn't even work...so
> I guess, the mods have to be made internally but I don't even want to
> go there.
>
> Looks like the FCC is turning their backs on this one. I have a
> Maytag top loader with a rotary "analog" switch and sure hope it
> doesn't "poop out" anytime soon. Hate to dig into my stash of ham
> radio $$$$.
>
> 73
> Tom /K1TL  k1tl at cox.net ...
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