[RFI] RFI from small indoor Xmas tree lighting 0.22 miles away.

[Dave]

How about a photo of your small loop...

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 1/4/22 20:07, Don Kirk wrote:
> I work hard keeping my noise floor on 160 meters low and hopefully equal
> between my 3 different pennant RX antennas that point 40, 160, and 300
> degrees from my QTH.  This winter I've struggled with an increased noise
> floor on my 40 degree pennant, and a few weeks ago I located a power pole
> that was arcing badly and this pole was subsequently repaired as I
> mentioned in a previous post.  The noise level on my 40 degree pennant came
> down substantially after repair of the pole, but I noticed it was still
> higher than my 160 and 300 degree pennants as well as its historical level
> by about 3 or 4 dB.  Yesterday I tracked the cause of the 3 to 4 dB
> increase in my noise floor to a home 0.22 miles away, and this afternoon I
> worked with the homeowner to quickly identify the root cause of the problem
> which turned out to be a power supply running the lights on his small
> indoor Xmas tree located on the second floor of his home.
> 
> I once again used a very small loop to sniff each circuit breaker in his
> circuit breaker panel to identify the suspect circuit, and when we shut off
> the suspect circuit breaker the RFI vanished.  The homeowner then unplugged
> one device at a time from the circuit until we found what device was
> generating the RFI.  Finding the suspect circuit took about 30 seconds
> using my sniffing loop, and then it took about 10 minutes to figure out
> what device on the circuit was the root cause of the problem.
> 
> I can't stress enough how important it is to not try and guess what device
> is causing the RFI because the homeowner was pretty certain it was due to
> his recent addition of a blower fan that he installed on his fireplace, and
> he even had me worrying about how difficult of a fix it would be if that
> was indeed the case as the wiring was within his walls.  I told the
> homeowner I never guess what device is causing the RFI because the problem
> is almost always different from case to case, and after we were done he
> fully appreciated my comment.  I use my laptop SDR receiver a lot to
> visually see what's going on (behavior of the RFI), but I don't use it to
> guess what the guilty device might be except for trying to determine if the
> RFI might be power line related RFI.
> 
> Using my small loop to sniff the circuit breaker panel is definitely a game
> changer for me, and it sure makes working with homeowners a much
> simpler task (very efficient, and least intrusive to the homeowner).
> 
> Here is a link to a video documenting this case for those interested:
> https://youtu.be/J6OjwTRNIvY
> 
> 73, and Happy New Year.
> Don (wd8dsb)
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