In a previous life I had a similar problem. That is: How to add ferrites to damp emissions that were NOT EUT generated without violating the intent of the emissions specification. In my case I had numerous (~20) shielded cables that went through a patch panel up to the measurement area. The shielded connectors were attached at the patch panel. A little experimentation soon showed that the emissions were being exacerbated by the termination of the cables at the patch panel. We designed an inverted top hat that bolted to the center of the turntable and essentially dropped the patch panel below the TT by about 8 inches. We then added ferrites to the cables inside the tophat - thereby preserving, to some degree, the correct test environment.
Maybe some sort of transition "housing" would be helpful to aid in the isolation of the feed cables? Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Email: charles.gra...@echostar.com; Email Alternate: chasgra...@ieee.org From: Pettit, Ghery [mailto:ghery.pet...@intel.com] Sent: Friday, February 07, 2003 9:21 AM To: 'Cortland Richmond'; Pettit, Ghery; ieee pstc list Subject: RE: EN 55022:1998 plus A1:2000 Cortland, Look at Figure 10 from Amendment 1 to CISPR 22:1997. It clearly shows clamps sitting on top of the turntable. Article 10.4 of CISPR 22:1997 (Amendment 1) states "All cables leaving the table-top EUT for a connection outside the test site (for example, mains cables, telephone lines, connections to auxiliary equipment located outside the test area) shall be fitted with ferrite clamps placed on the floor at the point where the cable reaches the floor (see Figure 10)." The wording is quite clear, as is Figure 10. If you can sell the FCC on your idea, great. I've been discussing this with them since 2000 and they haven't agreed to the clamps yet. Ghery From: Cortland Richmond [mailto:72146....@compuserve.com] Sent: Thursday, February 06, 2003 9:03 PM To: Pettit, Ghery; ieee pstc list Subject: RE: EN 55022:1998 plus A1:2000 Ghery Pettit wrote: >> The cables are specified to enter the clamp at the point where the cable reaches the surface of the turntable. I don't believe that your suggestion meets this requirement. << Yes, and I thought about that; if ferrites start where the cable enters the ground plane, that should comply exactly, and every time, whereas if a clamp were merely laid on top of a ground plane (it seems to me) a cable could easily be choked _before_ meeting the turntable. I believe the intent and the wording of CISPR22:1997 might be met by a ferrite clamp which is neither exposed above the turntable nor too far below it -- and that this may very well _also_ meet the FCC's requirements. The problem is, no matter what one asks about, one is likely to be told "no." You'd think that with MOU's and harmonization so talked up, the two sides of the Atlantic could at least agree that it might meet somewhere in the middle (grin). Cortland 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
