[RFI] RFI Canceling RFI?

[Pete Smith]

I wonder if maybe it is something else entirely.  A dozen years ago I had this sort of RFI on a couple of discrete frequencies in the 80-meter band.  I traced it to a neighbor's house, where we discovered that it was related to an upstairs bathroom's lights.  The odd parts - the lights were ordinary incandescent, and the interference was only present when the lights were switched *off* at the wall switch.

I replaced the wall switch - an ordinary 72-cent "silent" (non-mercury) switch - and that cured the noise.  A few weeks later, I discovered another emitter a little farther away in the development - same source, same cure.

Never did figure out what the mechanism could have been to account for it.

73, Pete N4ZR

At 10:06 PM 3/9/2006, Martin, AA6E wrote:
>Or it could be that one oscillator pulls the other off frequency? 
>Maybe the noise is still there, but at another freq.?  Most of my
>stuff that generates raspy spurs is very sensitive to line voltage,
>among other things.
>
>A random thought!
>
>73 Martin AA6E
>
>On 3/9/06, doc <kd4e at verizon.net> wrote:
>> Tom Rauch wrote:
>> >>  > I turned on a second compact fluourescent light while
>> >>  > listening to my shortwave radio, the first caused RFI,
>> >>  > the second CANCELLED it!!
>> >>  >
>> >>  > But the first only caused RFI in the same room as the
>> >>  > radio, the one in the other room had no effect on the
>> >>  > radio by itself.
>> >
>> > It's very easy obvious what happened when we work through
>> > this.
>> >
>> > 1.) Only one light makes noise, he stated that.
>> >
>> > 2.) The second lamp that does not make noise, when placed
>> > across the power mains, reduced noise from the only RFI
>> > generating lamp.
>> >
>> > The can only be one thing happening. The second lamp is
>> > loading the line and changing something so the power lines
>> > are detuned for noise (so it is a less efficient antenna or
>> > less well coupled to the RFI generating lamp).
>> >
>> > At my old house in Conyers, I had bad noise coming in on the
>> > power mains. The noise was generated in my neighbor's house.
>> > What I did was build a bypass capacitor with two 120VAC
>> > rated .01uF capacitors, each one tied from one side of the
>> > line to the safety ground, into a plug.
>> >
>> > I just moved that plug around to different outlets until I
>> > found one that detuned the power lines, and made the noise
>> > radiating from the lines in my house disappear. The noise
>> > virtually vanished even though I'm positive the source of
>> > noise several hundred feet away still remained.
>> >
>> > It's almost certain a the same thing is happening.
>> >
>> > 73 Tom
>>
>> Tom,
>>
>>     You are amazing!  Thanks for the answer to a paradox
>> wrapped in a puzzle twisted into a conundrum ... or
>> however that wonderful phrase goes!
>>
>> --
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Thanks! & 73, doc kd4e
>>
>>
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>>       KD4E     =====================================
>> West Central Florida
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>
>
>--
>martin.ewing at gmail.com
>http://blog.aa6e.net
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