[600MRG] 600MRG Digest, Vol 31, Issue 16

[sbjohnston at aol.com]

you are not responsible for all of those boards I have seen 
that have unpopulated pads and jumpers where the AC filtering stuff 
should be. They do the compliance testing with the parts that don't seem 
to get included in the shipping versions. 

 I've seen that as well.  I've also had several design engineers report to me that they include proper noise suppression (filters, shields, shielding paint, etc) in the prototypes but they found that the device as manufactured rarely includes them.  

Next time you see a device in which the filtering parts are missing could you take a photo for me?  Maybe also a photo of the outside cabinet that would identify the unit as well?  I'm on a crusade to fight consumer electronics noise and could really use hard evidence.  

Here's a paper and presentation I did for the broadcast engineering conference a couple years ago showing this problem...

http://www.wd8das.net/nab-paper.pdf
http://www.wd8das.net/nab.ppt

It focuses on the impact FM broadcast band because I was tired of my colleagues telling me that noise was just a problem for the AM band.  Of course we know it is a problem for LF, MF, HF, VHF etc... but I wanted to convince them so the presentation was geared that way.  

 


Steve 

sbjohnston at aol.com
http://www.wd8das.net/
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