[RFI] IR Illuminator for Security Cameras

[Jim Brown]

On 1/30/2022 10:55 AM, Michael Tope wrote:
> I am not aware of any interference from the IR LED arrays that are built 
> into the cameras, but just in case these illuminators are more 
> problematic I thought I would run this by the reflector before I press 
> the "add to cart" button.

Hi Mike,

Thanks for the QSO last night. Great to hear you on the air again.

99.9% of what gets plugged into the wall includes a switch-mode power 
supply, 99.99% of them are noise generators, and any attached wiring 
(like AC and DC cables) is an antenna that radiates the strong common 
mode component of the noise. Over the years, I've collected boxes of 
linear DC supplies, from which I find one to replace them. When they're 
built into a product (TV, stereo gear, refrigerator, etc.) serious 
common mode chokes on all attached wiring is the only solution, starting 
with those cables likely to be the strongest radiators.

DC-DC converters used inside products like computer speakers that power 
from USB are also noise generators. Neighbor W6GJB had so much on the 
pair in his shack that he could measure the common mode current with an 
MFJ device!

73, Jim K9YC