Re: Multiple shield terminations?
Some years ago, I had to show a TV-card vendor (their card made a compliant computer fail Class B) the right way to do this. They were passing normal video through, and had apparently never TESTED in standby mode to see what interrupting shields with pigtails would do. I bundled all the video cable shields - in their case only six - and terminated the whole bunch in common at the connector EMI backshell. That did it. As I recall, they wouldn't DO that, and we didn't buy their card. Good luck. 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 All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Multiple shield terminations?
Derek, Suggest using a connector having #(Conductors + Braids), pins. Bond all the Braid pins together and ground, (Or continue thru the connector as desired), via shortest connection. For symmetry, Braid Pin Ground Ring could be made around outside periphery of connector pins. Good Luck! Tony Firth, EE, Genus,Inc.,Sunnyvale,CA -- Hi Ken, I'm open to this, but the cables that pass through ( there could be as many as 10 ), all have their own braids, and are impedance matched. I really don't want to just squish them together and hope it makes good contact all around Not sure if I'd change the cables impedance ( they are impedance controlled cables ) at the clamping point Cheers, Derek N. Walton
MIL-HDBK-454 (Safety)
Over the years a number of US MIL standards have been replaced by MIL guidance handbooks (for instance MIL-STD-454 has been replaced by MIL-HDBK-454). The MIL standards were full of shalls whereas the MIL-handbooks are full of shoulds. This shift is rather unfortunate from a contractual point of view since MIL handbook 454, for instance, states that it cannot be used to place mandatory requirements and the designer need not comply with the guidance provided. This seems to be particularly unfortunate since MIL-STD-454 (Requirement 1) was probably the most important souce of MIL personnel safety requirements. The specifications for numerous US military items, however, still refer to this guidance handbook as if it is a repository of mandatory requirements. In reality this seems to me to leave the issue of what the equipment design actually complies with as completely undefined. I would like to hear any opinions as to how MIL-HDBK 454 is perceived from a contractual standpoint. How much freedom do US military equipment designers out there feel they actually have, given the complete lack of shalls? Dave Palmer, UK
Re: Multiple shield terminations?
Is this mil or commercial? Are they twisted shielded, or coax? There are of course MIL-C-38999 connectors with coaxial pins. If it is twisted shielded I doubt that a short length of shield termination would cause huge vswr to the intentional differential signal. Especially as a two inch termination is a tenth wavelength at 600 MHz. Likely I don't know enough about your problem. -- From: lfresea...@aol.com To: ken.ja...@emccompliance.com, emc-p...@majordomo.ieee.org Subject: Re: Multiple shield terminations? List-Post: emc-pstc@listserv.ieee.org Date: Sat, Jul 13, 2002, 11:10 AM Hi Ken, I'm open to this, but the cables that pass through ( there could be as many as 10 ), all have their own braids, and are impedance matched. I really don't want to just squish them together and hope it makes good contact all around Not sure if I'd change the cables impedance ( they are impedance controlled cables ) at the clamping point Cheers, Derek N. Walton Owner, L. F. Research EMC Design and Test Facility 12790 Route 76, Poplar Grove, IL 61065 www.lfresearch.com
Re: Multiple shield terminations?
Hi Ken, I'm open to this, but the cables that pass through ( there could be as many as 10 ), all have their own braids, and are impedance matched. I really don't want to just squish them together and hope it makes good contact all around Not sure if I'd change the cables impedance ( they are impedance controlled cables ) at the clamping point Cheers, Derek N. Walton Owner, L. F. Research EMC Design and Test Facility 12790 Route 76, Poplar Grove, IL 61065 www.lfresearch.com
Re: Multiple shield terminations?
What's wrong with the simple-minded approach - an EMI backshell? -- From: lfresea...@aol.com To: emc-p...@majordomo.ieee.org Subject: Multiple shield terminations? List-Post: emc-pstc@listserv.ieee.org Date: Sat, Jul 13, 2002, 3:03 AM Hi all, I'm faced with a situation where a number ( up to 10 ) of small ( 3mm ) shielded wire pais come together at a connector. I need to provide a peripheral termination for each shield. Has anyone come across and off the shelf solution for this? Alternatively, a good way of achieving this? Thanks, Derek N. Walton Owner, L. F. Research EMC Design and Test Facility 12790 Route 76, Poplar Grove, IL 61065 www.lfresearch.com
Multiple shield terminations?
Hi all, I'm faced with a situation where a number ( up to 10 ) of small ( 3mm ) shielded wire pais come together at a connector. I need to provide a peripheral termination for each shield. Has anyone come across and off the shelf solution for this? Alternatively, a good way of achieving this? Thanks, Derek N. Walton Owner, L. F. Research EMC Design and Test Facility 12790 Route 76, Poplar Grove, IL 61065 www.lfresearch.com
RE: China approvals - CCC
Scott, Go to www.siemic.com , click ccc to download a 10-page complete introduction of CCC mark. Leslie Scott Douglas dougl...@naradnetworks.com wrote: Can anyone provide web links to look at these catalogues? I am interested to see if our products are on the list. Thanks, Scott At 08:02 AM 7/12/02 -0700, Joshua Wiseman wrote: Amund, I think you should also take a look at the old CCIB scheme. The CCC is still developing standards at this time. I believe it is safe to say that if your product was in the catalog for CCIB it will be for CCC as well. I also understand that CCC will cover more products than CCIB did as well. If nothing else keep your ear to the door you may find yourself working toward CCC approval in the future. Good Luck, Josh Josh Wiseman EMC/Product Safety (714) 368-2737 [mailto:jwise...@printronix.com] -Original Message- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: Friday, July 12, 2002 1:39 AM To: Emc-Pstc Group (E-mail) Subject: China approvals - CCC Hi all, Rules and Procedures for Compulsory Product Certification were implemented on May 1, 2002. The certification mark is referred to as China Compulsory Certification (CCC). The first Catalogue of Products Subject to Compulsory Certification is now released. Question: If my product is not listed in the catalogue, does it mean what I do not have to document compliance to the EMC or electrical safety requirements ? no need for Chinese certification ? I have be told so via competent sources. I would like to check the discussion form for other views. Best regards Amund Westin, Oslo/Norway --- 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 All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list - Do You Yahoo!? New! SBC Yahoo! Dial - 1st Month Free unlimited access
RE: Open chassis computers for sale - with neon lights?
George, The method for testing motherboards is intended to be combined with the DoC method of declaring compliance based on individual testing of the components that comprise the full computer system, i.e. Assembled from tested components. The final computer system is still required to meet the FCC Class B limit just as if it was tested, even though it was not. I suppose that a small (extremely small) chance exists that the final system could pass if tested. The loophole here may be the Home-Built devices clause, Title 47 part 15.23. Where the device is not marketed or constructed from a kit. This allows for five or less devices built for personal use without the need for compliance testing (FCC only). Jeff Klinger Director EMC Engineering Compatible Electronics, Inc. Ph: 714-579-0500 Fx: 714-528-8984 http://www.celectronics.com NARTE Certified ATL-0180-E -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of George Stults Sent: Friday, July 12, 2002 3:11 PM To: 'emc-p...@majordomo.ieee.org' Subject: Open chassis computers for sale - with neon lights? Hi Folks, I just walked into three local computer stores (west coast, USA) and found that desktop computers have become art forms. There are computer cases for sale with large plexiglass windows about (10in x12in), some with a fan in the middle of the plexiglass panel, and inside the case, there is a 12 inch long neon lamp, powered from the ATX power supply just like any installable drive. Through the window, one can see the motherboard, CPU heatsink, etc, all illuminated by the Neon light. Its the latest in computer fashion, I suppose. I asked a few questions at the stores and found at there are least 2 manufacturers, and that one can obtain kits on the internet to do the same modification at home. After looking at the computer cases, I would expect them to radiate about the same as an open chassis though possibly more directional. My question would be, is there any loophole through which this is legal, or is this the blatant violation that it looks like. I've heard that there is a requirement for computer motherboards to fall within some radiated level with an open chassis. Is that correct and could that be the rational here? George Stults --- 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 All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- 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 All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
