I suppose it could be line cord radiation, as some have thought. In cases like this, I like to measure the hf currents on all cables, including the line cord (with current probe). This often reveals answers to weird problems like this. Are the cables in precisely the same arrangement in both sites? How's the line filtering? Usually, this is not an issue if the product's line filter is working OK. Try adding another line filter in series with the existing one as a test. Try spacing large ferrites all along the line cord. Maybe even shield it with aluminum foil back to the product chassis. You also might try a comb generator with "short" monopole to compare sites. It's not unusual for two sites to differ by several dB at certain frequencies. You might check my web site for reviews of a couple recommended generators.
Just a short brain dump! Ken _______________________ Kenneth Wyatt Wyatt Technical Services LLC Woodland Park, CO Email Me! | Web Site | Blog Subscribe to Newsletter Connect with me on LinkedIn On Feb 12, 2011, at 1:24 PM, Brian O'Connell wrote: > Good People, > > Have tested at several sites. All are 'big' names and have a good reputation. > > The 10m fully anechoic chamber data indicates from +5dB to +11dB in several frequencies; while the 10m OATS says the unit passes Class B, min -4.2dB. > > Huh?!? What is the physics behind the difference between an outside site and absorbers? Where are the Borg when you need them? > > Brian > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://product-compliance.oc.ieee.org/ > Graphics (in well-used formats), large files, etc. can be posted to that URL. > > Website: http://www.ieee-pses.org/ > Instructions: http://listserv.ieee.org/request/user-guide.html > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
