I read in !emc-pstc that Cortland Richmond <[email protected]> wrote (in <[email protected]>) about 'Measuring a ferrite performance' on Thu, 18 Dec 2003:
>This of course does not tell you the >impedance of beads, only attenuation in the fixture, or one the cord, >but may be enough. The attenuation is often what you want to know. BUT it's also significant whether the bead *absorbs* the energy that it doesn't pass on, or *reflects* it. If it reflects, it may make emissions worse instead of better. So it's a good idea to look at the input impedance as well as the attenuation. Presumably 150 ohms is good, on the basis that the EMC standards assume that that is the common-mode impedance to ground of any cable. -- 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.ieee-pses.org/ 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
