[amsat-bb] AMSAT: RFI from LED bulbs?

[Phil Karn]

On 10/22/18 7:49 AM, Paul Andrews wrote:
>
> I have at least 100 RFI generating LED lights in a box in my basement.
> I removed these from my home and my neighbors.  I have exchanged bad
> LED lights for good LED lights.  My house is 100% incandescent and
> fluorescent.  No LEDs as long as I'm operating EME on 144 and 432 MHz.
>   LED noise does not reach up into 1296 MHz.

Can you tell us the makes and models of the offending lights? Maybe show
pictures?

Our house is full of LEDs. While I have noise problems they seem to be
coming from the usual culprits -- nearby switching supplies that I'm
methodically finding and fixing or replacing. I don't seem see much
coming from the lights.

With one exception -- when my wife turned on the lights in a room that
isn't used much at the moment, I saw LF noise on my waterfall. Turns out
that fixture contains a CFL that we haven't replaced with an LED yet. So
our experience has been the opposite of yours, though I must point out
that I've been looking mainly at LF through HF these days. I haven't
done a systematic scan of VHF or UHF.

My understanding is that many LED bulbs use series strings of diodes
with the current limited by the reactance of a capacitor. This seems
like it ought to be quieter than the ~20 kHz AC inverter commonly used
in CFLs.

Phil