On 4/8/2022 5:51 PM, Don Kirk wrote:
Turns out the RFI was from a Hi-Fi Digital Amplifier MN180BT or its
power supply located 0.27 miles from my house.
The clue may be "Digital Power Amp," meaning not an analog output stage,
but a digital one, known in that world as "Class D." In which case the
output stage is not properly low-pass filtered differentially, and the
antenna would include speaker wiring. If you can chase down a mfr, that
might help.
Some fixes if it's differential -- replace speaker wiring with twisted
pair. If they're audiophiles, use #12 twisted (homebrew by twisting with
a drill motor with the other end in a bench vise). Twist it more than
you need, let it sit at least overnight before releasing. It will
untwist a bit, but that won't matter.
For common mode, of course, the usual turns of #31.
Let us know what you learn at what works.
73, Jim K9YC
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