[RFI] CFL Noise Update - Neighbor Removes Burned Out CFL

Al K0VM al.k0vm at yahoo.com
Tue Oct 9 12:35:00 EDT 2012

   This may be a bit of a stretch...
   It could be possible that turning on the switch in our house 
effectively changed the pattern of your receive antenna in the direction 
of the bad CFL... i.e. created a null in that direction in one switch 
position but not in the other ( especially if you antenna is near you 
house wiring ).   The wiring in your house does have resonances and 
transmission line effects that could change when a switch is flipped.

   Did just the level of the interference change when you flipped the 
switch or did the interference shift frequency.

   Any way, just glad you found the source of the problem.


On 10/9/2012 1:01 AM, Tony wrote:
> All,
> I recently discovered that my neighbors CFL lighting was causing RFI. 
> I managed to get close the light with a portable HF rig and found the 
> noise was identical to what I was hearing in the shack; same 
> frequencies, same noise characteristics. I should mention that the 
> bulb was burned out.
> The problem with pointing the finger at the light as the only RFI 
> source was that the noise would shift in frequency when I turned a 
> light switch on and off in my home! I recorded the frequency shift 
> "trick" on video: http://www.youtube.com/watch?v=EYHbpLfQ1gc
> I shut the mains to see if the noise was coming from my home, but it 
> was still there with the breakers off. The light switch had no effect 
> on the noise as long as the mains remained off.
> Long story short:
> The noise went away immediately the moment my neighbor removed the 
> burned out CFL. An identical CFL that was working emitted much less 
> noise. He hasn't replaced the bulb yet so we'll have to see what 
> happens with the new one.
> The puzzling thing about all this is how a light switch in my home 
> could have an effect on the noise coming from a neighbors CFL? It 
> doesn't appear coincidental because the light switch "trick" hasn't 
> happened since my neighbor removed the CFL. It's been a while now and 
> all is quiet.
> Any ideas?
> Tony -K2MO
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