I was interested in the recent posts regarding light dimmers, as this is
a significant issue for me. We have three dimmers in our house, and
three more in a guest house directly behind. As of yet, the brand name
on all of these is unknown. Banning dimmers from these houses is not an
Currently I'm operating on 630m and listening across the MF/LF spectrum,
where RFI from these devices seems much stronger than at HF. The
strongest RFI is getting into a receiver in our main house from dimmers
in the guest house, which is physically closer to the receiver's antenna
but on a different power service drop. So I'm wondering if the RFI is
traveling through AC wiring, or if it might be getting from the dimmers
to the antenna. The shack gear's power is all filtered, through
Tripp-Lite power strips and wrapping AC cords through FT240 toroids.
I noticed that one or two people here mentioned having good luck with
Lutron dimmers, but others cited issues with these.
I see the ARRL RFI Book states, "The best cure is to replace the control
with a better one that has a built-in RFI filter. (Beware of dimmers in
plastic cases!)" It also discusses placing an AC line filter at the
dimmer, as well as one or two common-mode chokes made by wrapping AC
wiring around an F(T)-240 or F(T)-140 ferrite core.
Lutron has this application note on RFI and dimmers:
It mentions Lamp Debuzzing Coils (LDCs) as "the most effective way to
So I'm wondering about the best things to try as next steps. Are some
Lutron models more effective than others? If the RFI is originating in
our guest house on a different service drop, is it likely that adding
filters to the AC supply to the dimmers there would help? Has anyone had
any luck with LDCs?
Thanks for any suggestions,
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