[RFI] Guidance on finding noise?

[Jim Brown]

On 1/12/2020 10:14 AM, Lee STRAHAN wrote:
>   The point to all this is try looking at the noise with a SDR radio that should give you a wider bandwidth picture.

RIGHT! It is quite likely that the noise K2KW and crew are chasing is 
NOT generated by the power system, but rather some electronic or power 
control device in a home or business. Traditional methods used to "pin 
point a pole" make no sense for this kind of noise, which is why I keep 
on saying "LOOK AT THE SPECTRUM."

The traditional methods that ARE applicable are what Lee describes and 
loop antennas, in both cases connected to 1) an RX with a spectrum 
display (best) or 2) a portable RX using a loop antenna that tunes to 
the frequency(ies) where you hear the noise. For example, the broad 
coverage RX in my Kenwood TH-F6A talkie uses an internal loopstick below 
10 MHz; the antenna input can be manually switched between that loop and 
the SMA connector.  That's the upside; the downside is that it's not 
very sensitive, so you have to be either pretty close to the source or 
an external loop needs a preamp.

Another very important point -- virtually all noise generated by the 
power system is IMPULSE NOISE that is the result of arcing, and it looks 
like horizontal lines on a fast waterfall. Electronic noise, including 
that generated by power-handling and control equipment like motor 
controllers, industrial equipment, and switch=mode power supplies, looks 
like humps on a spectrum display and slightly "squiggley" trails of 
those humps on a waterfall.

A study of NK7Z's website is quite worthwhile. I also strongly STUDYING 
my own application note. k9yc.com/publish.htm

Bottom line -- audio frequency spectrum and o-scopes are the WRONG tools 
for anything but impulse noise, and a spectrum display is the RIGHT tool 
for electronic noise.

73, Jim K9YC