Hi All, Just wanted to put my 2 cents worth in. The same thing may be happening in Mil-spec testing. Recently, I was at a client's site for a purpose unrelated to this story.
I noticed interference to the measurement I was trying to make on a piece of equipment. The equipment had enough common mode current on its leads to fail emissions, even though it was turned off! There was a military battery charger for small batteries on their bench so I connected my current probe to its power cord and noticed enough common mode current to cause a 30 dB+ failure of emissions over a broad frequency range. I would suppose the battery charger had been tested to mil-specs. If so there is a problem here, even accounting for the repeatability problems in mil-spec testing. Doug Grasso, Charles wrote: > Hi Derek - Go Reds!! > > This is not a surprise to me. I have railed at much length a couple > of years ago as to the latest FCC changes to the emissions > qualification. I am sure you are familiar with it so I won't > belabour the point. Fundementally the FCC PC emissions procedure > has rendered the EMC discipline almost irrelevent. The new procedures > coupled with the lack of enfocement makes it difficult to justify > the increased costs of EMC design & test. It also makes the > whole measurement uncertainty push ridiculous. After all > if the procedures allow for prodcut that 20dB out of spec why > bother with a couple of dB of error?? > > Lets give the emissions standards some teeth or eliminate it > all together. > > Best Regards > Charles Grasso > Senior Compliance Engineer > Echostar Communications Corp. > Tel: 303-706-5467 > Fax: 303-799-6222 > Cell: 303-204-2974 > Email: [email protected]; <mailto:[email protected]; > > Email Alternate: [email protected] <mailto:[email protected]> > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > Sent: Tuesday, March 25, 2003 1:05 PM > To: [email protected] > Subject: OK, what's going on? > > Hi all, > > This e-mail has been prompted because of a number of things that > have all come together. This may take a little reading, but please > stick with it. > > Last note... this is not intended to pick on any individuals, or > organization, but I do want to stir the pot. > ...... -- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: [email protected] \ _ / ] \ _ / Website: http://www.dsmith.org This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
