The fact that it is frequency stable, not drifty, rings me a bell.
SMPS noise is drifty.
Perhaps after shutting down the house-mains and with a portable receiver
with ferrite bar antenna (MW band tuned, so you can estimate where the
noise come from, although you'll get two directions), will help to track
the source.
Regards
Guillermo - LU5WE.
El 24/1/20 a las 12:40, August "Gus" Hansen escribi�:
On 1/23/2020 11:59 PM, Dick Bingham wrote:
...
These signals are frequency stable and not drifty. Shutting down the
house-mains with the receiver battery powered does not kill the QRM.
SO, it looks like something somewhere is generating this junk that
runs from
the BC-band to >20MHz.
Shutting the main power off won't stop cable modems and routers from
operating if they have battery backup. Some of these devices can be
quite noisy. Also, do you have any UPS units keeping other equipment
alive during power outages?
Good luck,
Gus Hansen
KB0YH
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