Jim,
I bravely opened up one of these light just out of curiousity. There is a
green wire connection to the board and also it’s run to the metal of the light
fixture. I didn’t go any more deeper into it as it would be unsoldering wiring
which I didn’t want to do. The board has many components. I am wondering if
it’s radiating directly or it’s using the power wiring as antenna. I should
try one of my large ferrites and loop several turns though one and see if
there’s a change, I’m skeptical though.
Dale, K9VUJ
On 13, Jun 2018, at 18:22, Jim Brown <jim@audiosystemsgroup.com> wrote:
On 6/13/2018 12:48 PM, Stephanie WX3K via RFI wrote:
> Here is a helpful link
> https://www.digikey.se/Web%20Export/Supplier%20Content/Lambda_285/PDF/TDKLambda_all_about_emi_epmag.pdf
>
> If you search Amazon by entering EMI filter you will find a variety for
> different applications.
BUT THE LINK IS WRONG! It is the EMC compliance tech's view of the world.
These filters work ONLY if properly mounted and built INTO equipment. In
general, they do NOT work for most real world problems that put noise on the
power line as current on the green wire.
The most common cause of noise coupling to and from power and signal wiring is
that the green wire, or the cable shield, fails to contact the shielding
enclosure at the point of entry/exit. This puts noise current on the green wire
of the cable shield, and it causes noise current on the cable shield to enter
equipment. Neil Muncy, ex-W3WJE (SK), first exposed this in 1994, and a fellow
member of the AES Standards Committee Working Group on EMC named it "The Pin
One Problem." See my website for a lot of tutorial material on this.
The only fix for this (without modifying equipment) is a ferrite common mode
choke. And simply clamping a few onto the cable does NOT WORK at HF. Those
clamp-ons are designed for VHF noise. Study
k9yc.com/RFI-Ham.pdf and
http://k9yc.com/KillingReceiveNoise.pdf
73, Jim K9YC
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