I read in !emc-pstc that Alex McNeil <[email protected]> wrote (in <5685ADDE2285D511925200508BB9F5031EC502@fort2>) about 'Transverse Balance Limitations 68.310_On Hook' on Thu, 19 Jun 2003: > >Hi All, > >Thanks to all who responded to my query. I will inform you of my findings as >soon as I have a solution. > >Kind Regards >ALEX > >-----Original Message----- >From: Alex McNeil >Sent: Tuesday, June 17, 2003 10:09 AM >To: '[email protected]' >Subject: Transverse Balance Limitations 68.310_On Hook > > >Hi Group, >Can you help here. I pass the above FCC Part 68 specification when my >product uses a Linear Power Supply but fail when I use my alternate Switch >Mode Power Supply. Why should this be?
I didn't see your original message. In Germany, it has been found that the conducted emissions on the mains lead, due to an SMPS in a computer, vary according to whether the modem is connected to a phone line with good balance or poor balance! This seems to be something of an opposite effect to the one you are finding. I think the first question you need to answer by measurement is whether emissions (possibly out-of-band) from the SMPS are causing the apparent lack of balance. The on-hook balance is presumably determined by measurements that effectively (or indirectly) compare the impedances >from each leg to ground. If there are spurious emission voltages on the legs, and the measurement equipment responds to them, this must make the impedance determinations inaccurate. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! 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
