If you do find that a better USB cable (superior shield, possibly with a molded ferrite) results in a pass, then that part would become a “critical accessory” and ideally be included with the product when shipped. It should be specified in the user instructions with enough detail that the user cannot accidentally substitute with something inferior.
Ralph Vancouver, BC From: Larry K. Stillings <[email protected]> Sent: May 21, 2026 7:25 AM To: [email protected] Subject: Re: [PSES] 12 Mbps USB and Ultrasound EN 61000-4-39 Immunity issues I 2nd that. We started getting clear jacketed cables in the lab just so we knew the shields were properly terminated on both ends. Here’s a picture of one with just a drain wire for ground. It’s a very common problem. Larry K. Stillings Compliance Worldwide, Inc. Test Locally, Sell Globally and Launch Your Products Around the World! FCC - Wireless - Telecom - CE Marking - International Approvals - Product Safety 357 Main Street Sandown, NH 03873 (603) 887 3903 Fax 887 6445 complianceworldwide.com <https://complianceworldwide.com/> Follow us on social media linkedin.com/company/compliance-worldwide-inc x.com/complianceww Privileged/Confidential Information may be contained in this message. If you are not the addressee indicated in this message (or responsible for delivery of the message to such person), you may not copy or deliver this message to anyone. In such case, you should destroy this message and kindly notify the sender by reply email. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of my firm shall be understood as neither given nor endorsed by it. From: Jim Bacher, WB8VSU <[email protected] <mailto:[email protected]> > Sent: Thursday, May 21, 2026 10:21 AM To: [email protected] <mailto:[email protected]> Subject: Re: [PSES] 12 Mbps USB and Ultrasound EN 61000-4-39 Immunity issues Charlie, first thing I would try is making sure they are using a high quality USB cable. Cheap cables will have issues. Jim Bacher, WB8VSU [email protected] <mailto:[email protected]> JBRC Consulting LLC Product EMC & Regulatory Consultant https://www.trc.guru/ <https://trc.guru/> email:[email protected] IEEE Life Senior Member On May 21, 2026 10:15:39 AM Charlie Blackham <[email protected] <mailto:[email protected]> > wrote: Client is having problems testing a legacy medical device at failing near field 13.56 MHz immunity as per EN 61000-4-39 The product has an external ultrasound probe and connects to a tablet via USB running “high speed” (12 mbps) The PIC only supports this USB rate and we’re seeing the ultrasound measurement being affected and the USB connection dropping out and no reconnecting. The product is in a plastic enclosure 😊 Has anyone seen similar issues and been able to resolve them without a suitable metal enclosure? Best regards Charlie Charlie Blackham Sulis Consultants Limited Mead House Longwater Road Eversley RG27 0NW UK Tel: +44 (0)7946 624317 Email: [email protected] <mailto:[email protected]> Web: https://sulisconsultants.com/ Registered in England and Wales, number 05466247 _____ This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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