[RFI] 160m-5mhz noise?

Paul Christensen w9ac at arrl.net
Fri Nov 6 03:18:16 PST 2009

> Just to say that switch mode supplies CAN be made to be as RF quiet as any 
> linear supply.


The problem is not pervasive with legitimate companies like Astron, Samlex 
and scores of other switch-mode producing technology companies.  To a large 
extent, the problem comes from off-shore Asian suppliers of subassemblies 
that become embedded into appliances -- appliances that require no FCC 
certification in the U.S. under Sec. 15.103(d).  Moreover, importation rules 
under Sec. 2.1204(a)(2) exempt from certification and equipment 
authorization all radio frequency devices being imported into the U.S. where 
such devices do not otherwise require FCC certification (e.g., appliances 
under Sec 15.103(d).)  Quality companies seek some form of certification for 
their devices whether they are compelled to comply -- or not.  Most 
importers don't care and seek only to design their products with the minimal 
amount of quality and testing required (if at all) to get the product into 
the market.

As another example, I recently installed halogen accent lighting in my home 
office and discovered that a switch-mode "electronic transformer" was 
spraying gross amounts of RF into my home electrical wiring.  The unit 
contains no certification labeling and is imported from Malaysia.  This was 
no on-line Internet purchase; it was purchased from my neighborhood Home 

So, when I state that the problem is growing as a result of the expanded 
proliferation of switch-mode technology, it's a fact.  Unfortunately, the 
bad guys are out-numbering the good guys -- and it will stay this way until 
the Commission acts on it own or through a Petition for Rulemaking to amend 
Part 15 to reflect the reality of the times.

Paul, W9AC


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