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)
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