[RFI] Sinusoidal type noise on 6 meters

[Jim Brown]

On 11/19/2023 5:46 PM, Stephanie WX3K wrote:
> I was finally able to capture it again with a wider span
> 
> hqdefault.jpg
> November 19, 2023 <https://youtu.be/Haz0-f8s318>
> youtu.be <https://youtu.be/Haz0-f8s318>
> 
> <https://youtu.be/Haz0-f8s318>

This is clearly power-handling electronics, the most common sources of 
which are switch-mode power supplies for equipment that convert 120V AC 
to the fairly low DC voltage used by almost everything that we plug into 
the wall. The average home has several dozen of these noise makers. 
Other common sources include controllers for variable-speed motors that 
run everything from HVAC systems and heat pumps to elevators in public 
buildings. Equipment in factories are another potential source.

This noise is NOT sinusoidal -- we're looking at frequency spectrum. 
Each one of those humps is a harmonic of the switching frequency used in 
the equipment generating the noise. What appears to be sinusoidal is 
modulation of the carrier by noise.

Now it's time to doing some direction finding. It's NOT power line 
noise, but it could be from a source connected to the power system, like 
lighting, chargers for battery backup, etc. But it's NOT the arcing 
(impulse noise) that is characteristic of virtually all noise generated 
by defective equipment in the power system itself.

Follow suggestions in my noise tutorial about probing for sources in 
your own home with a battery operated receiver. k9yc.com/publish.htm

73, Jim K9YC