A generation ago I was involved with EMI testing of computer products. Most of the products our lab tested were PCs (XT, AT), and peripherals (printers, monitors, Modems, Display Adapters, etc). Printer cable was always a key issue. We would always use Belden cables with the printers, as they were double shielded with proper shield termination. If ferrite clamps were required to pass then the report would state it, and customer would be advised to provide the ferrite clamps with the product.
Regards Ravinder Ajmani HGST, a Western Digital company 5601 Great Oaks Pkwy San Jose, CA 95119-1003 [email protected] -----Original Message----- From: Gary McInturff [mailto:[email protected]] Sent: Thursday, September 04, 2014 9:31 AM To: [email protected] Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum Playing the devil advocate here only because I find this interesting and I'm not advocating anything. Heck I'm probably just arguing for argument sake. If all cables are not equal as Ghery and note and the designer/manufacturer has knowledge of that don't the cables then become special accessories in their own right? Under 15.27 c) They would not normally be considered special accessory items under the definition because they can be easily purchased at a multitude of locations. 15.27 c) Accessory items that can be readily obtained from multiple retail outlets are NOT (my emphasis) considered to be special accessories ... But given the knowledge of the designer/manufacturer that cables vary in performance and not all cables were tested the only assurance they have that the system will perform as intended is buy telling the consumer exactly which cable they must use buy name and brand. But if they do that then the cable isn't "readily obtained from multiple outlets" and is now by definition a special accessory. Paragraph 15.27 says that "The party responsible for the equipment, as detailed in ยง2.909 of this chapter, shall ensure that these special accessories are provided with the equipment" So now must the cable be provided? Gmac -----Original Message----- From: Pettit, Ghery [mailto:[email protected]] Sent: Thursday, September 04, 2014 12:46 AM To: [email protected] Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables You are highly unlikely to find the ferrite prayer beads at Best Buy. If you don't specify which ones to get you have no idea what the result will be. I think you are correct, the beads must be shipped with the product. The right ones, to boot. Now, how does the designer know that he needs ferrite beads? My experience has been that many (most?) HDMI cables do not have their shields terminated properly, if at all. Once the shields are terminated correctly problems go away. Could this be a better solution? Ghery S. Pettit - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
