Excellent report. Thank you very much for doing the measurements and
writing up the report. Very useful to the group.
I had a similar experience with a Lutron (model CL) dimmer I recently
bought. I tried it with both incandescent and LED lamps (a Philips LED
that was rated for dimmer use). I had very similar results to yours in
using a portable shortwave radio to qualitatively judge the RFI. The LED
was worse than the incandescent but both were problematic at BCB and 160M.
I also observed the highest RFI at 50% setting. When a SMPS is chopped at
the line rate the poor PWM circuit is forced to go through its startup and
shutdown sequences repeatedly. Adding a CM choke of any size at the dimmer
itself is a chore because the electrical box is too small to accommodate
it. There would need to be some sheet-rock removed and the choke installed
in a second NEC box. The lamps the dimmer would be driving are overhead
embedded in a soffit. I would rather not deal with that either.
Given that the antennas are very close to the house there will be no
dimmers at this QTH.
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