Jim,
Just re-read your post. The green wire goes first to the PCB, then is spliced
and goes to a point on the metal part of the light. Would that be a
difference? I should maybe take the green wire first to the metal of the
fixture then to the PCB. I have trouble with that, it just doesn’t seem like
that would cure the problem. I’m willing to try it though.
Thanks again
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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