[RFI] Don't ask, "What is it?" Instead, ask, "Where is it?"

[Paul Christensen]

> I might try to apply those words of wisdom and,
> "just find it"

The question of "what is it?" is not completely irrelevant.  Before the 
"just get out and find it phase," one really needs to know the noise pattern 
category.  Time spent in localizing the noise source is significantly 
reduced if, for example, the interfering noise is at least initially 
identified as either power line or switch-mode based.  Isolating the root 
cause of those two very different types of noise source requires a different 
set of tools and methodology.  You can end up wasting an awful lot of time 
trying to locate a SMPS problem with a complex RFI diagnostic tool from 
Radar Engineers.

Paul, W9AC