[RFI] RFI on 40 meters tracked down to Solid State Mini Fridge

[Dave (NK7Z)]

The entire HF spectrum is getting out of hand due to lack of proactive 
enforcement...  It took me two years to get a reasonable level of RFI, 
and it is now creeping up again...  Sigh...  I need to live in the 
middle of the NV desert but my wife says no!  :).

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


On 1/13/25 09:16, Don Kirk wrote:
> Sometime in December I noticed my noise floor on MF and HF increased and it
> was very noticeable on 40 meters (9 dB increase on 40 meters).  My
> stationary pennant RX antennas (I have 3 of them) indicated the RFI was
> arriving from a heading of 100 degrees.  I then used my portable flag with
> the DX Engineering preamp and my laptop based SDR receiver in the backyard
> and it also indicated the RFI on 40 meters was arriving from a heading of
> 100 degrees.  Using the portable flag I quickly determined the RFI was from
> a neighbor's home on an adjacent street which is about 200 feet from my
> pennant RX antennas.  The portable flag continues to be my most useful
> MF/HF DFing antenna and it once again allowed me to track down the property
> where the RFI was originating from in just a few minutes (having a
> unidirectional MF/HF antenna for DFing is priceless).
>
> Yesterday evening I went to my neighbors house and we sniffed the circuit
> breaker panel and most of the circuit breakers were just screaming RFI.  We
> did notice a couple of circuit breakers that were about 6 dB above the
> others (they were bedroom related) and sure enough one of them when shut
> off caused the RFI to disappear.  My neighbor then went upstairs to the
> bedrooms and started unplugging devices while I sat on the main floor
> watching my SDR receiver using a 12 inch untuned shielded loop antenna with
> preamp and we quickly determined that the RFI was originating from a mini
> refrigerator that was one of their sons Christmas presents this past Xmas.
> These mini refrigerators (solid state) are somewhat of a novelty item as
> they are cute little retro looking Frigidaire refrigerators but
> unfortunately they look like a good RFI generator too.
>
> Next step will be to try various filters that I have on the power cord to
> see if we can eliminate the RFI.  Note: The fridge plugs directly into a
> 120 Vac outlet (no external power supply) and it uses a 2 prong plug.  It
> also has a power jack if you want to power it with a 12 Vdc 3 amp power
> supply.
>
> I just uploaded a video onto youtube that documents this case for those
> interested, and here is the YouTube link: https://youtu.be/58B7wtsBIP4
>
> P.S.  I'm continuously encountering new devices in my neighborhood that
> generate excessive RFI and if it were not for my intense and rapid efforts
> in tracking down the RFI I would have an out of control situation.  I'm not
> sure how most other hams are surviving, and it's a really unfortunate
> situation.  My opinion is that we need to support the ARRL RFI department
> as much as possible as RFI is a real threat (I know I'm preaching to the
> choir).
>
> Just FYI, and 73.
> Don (wd8dsb)
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi