Hi Jim, It is likely that you have two sources of RF noise. The emission you are seeing the sum of both. I believe one is narrowband the other is broadband.
The broadband could be from a number of sources but is usually not too difficult to suppress. The trick is to identify all the sources. It looks as if the narrow band emissions are spaced exactly 14 MHz apart >from one another. So the fundamental of the emitter is running at 14 MHz. Find out what it is and take care of that at the source if you are able. Regards, -doug From: [email protected] [mailto:[email protected]] On Behalf Of Jim Eichner Sent: Monday, May 14, 2007 1:27 PM To: EMC PSTC Subject: Pre-selector trouble? We're running a radiated scan in the 30-200MHz range on a power conversion product that has broadband noise throughout. The data is showing evenly spaced discontinuities at 44MHz, 58MHz, 72MHz, and 86MHz. There may be others at higher frequency but if so they are subtle. By "discontinuity" I mean the data takes a sudden jump upwards, with the magnitude of the jump being different at each frequency. The testing is being done with the typical HP 856XX rack that everyone has. Does anybody have any ideas what the problem could be? I suspect our aging HP85685A pre-selector, based on the nature of the issue we're seeing, and on its history of unreliable operation. Thanks for your help, Jim Eichner, P.Eng. Compliance Engineering Manager Xantrex Technology Inc. e-mail: [email protected] web: www.xantrex.com Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
