[RFI] 160m-5mhz noise?
w9ac at arrl.net
Sun Nov 8 10:08:02 PST 2009
> Just to say that switch mode supplies CAN be made to be as RF quiet as any
> linear supply.
While a switch-mode supply can be made as quiet as a linear supply,
oftentimes they are not. The quality power supply brands are generally not
a problem. The problem more often is from an Asian import "brand "X"
I have two-switch mode station supplies that are completely RF quiet. My
prior point was that as more switch-mode technology is deployed, a larger
number of poorly-designed supplies will exist around our neighborhood
households, especially when poorly-designed switch-mode technology is
embedded into our "quality brand" appliances -- appliances exempt from a
It's also true that more well-designed supplies will be around us -- but
those supplies are not the problem unless they fail in a mode that produces
RFI. I've never seen a linear supply fail in a mode that produces S9 noise
at a distance of 500 feet. At most, the output filtering may develop noise
or ripple and its generally contained to the DC power bus, but unless its
some extremely abnormal condition, the noise/ripple does not propagate like
a switch-mode supply.
More information about the RFI