[PSES] 2 simple questions on EMC
Hi, 1. Our unit is passing by a whisker, under 1dB @ 30 Mhz in a 3m chamber against SubpartB requirements. Can we expect margin to improve in a 10m chamber? 2. It's lightly loaded in the chamber (10% of FL), we do expect the peak to squash down a bit with full load; they do when going from zero load to 10%. 3. We were idly wondering about cable loop; the output cable (bundled AWG #6) is 6' runs about 12" in front of the unit towards the antenna and the balance of it is currently coiled up in a loose bundle under the test setup. The standards don't say anything about cable routing, just that it should be on the ground plane. I don't like it running 'in front' of the unit, but the lab tech says that's pretty standard and not driven by the necessities of the test setup. Is that standard for a radiated setup? Colorado Brian - 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 All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: _ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
Re: [PSES] 2 simple questions on EMC
The EMC standard with which I am familiar (CISPR11, EN55022) are well written and provide examples of best practice setup and how to arrange excess cable length. I suggest going over the standard with the test technician at the EMC lab to better understand the requirement. If it were my product, I wouldn't lose a minute's sleep over a 1dB pass at a narrow range of frequency in the test spectrum, however, I would want to test at rated power. You may find that peak rises with increasing EUT power. Ralph From: Brian Gregory Sent: Tuesday, October 31, 2023 2:29 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] 2 simple questions on EMC Hi, 1. Our unit is passing by a whisker, under 1dB @ 30 Mhz in a 3m chamber against SubpartB requirements. Can we expect margin to improve in a 10m chamber? 2. It's lightly loaded in the chamber (10% of FL), we do expect the peak to squash down a bit with full load; they do when going from zero load to 10%. 3. We were idly wondering about cable loop; the output cable (bundled AWG #6) is 6' runs about 12" in front of the unit towards the antenna and the balance of it is currently coiled up in a loose bundle under the test setup. The standards don't say anything about cable routing, just that it should be on the ground plane. I don't like it running 'in front' of the unit, but the lab tech says that's pretty standard and not driven by the necessities of the test setup. Is that standard for a radiated setup? Colorado Brian _ 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 All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ <https://www.mail-archive.com/emc-pstc@listserv.ieee.org/%20> Website: https://ewh.ieee.org/soc/pses/ <https://ewh.ieee.org/soc/pses/> Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) <https://ewh.ieee.org/soc/pses/list.html> List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net <mailto:msherma...@comcast.net> Rick Linford at: linf...@ieee.org <mailto:linf...@ieee.org> For policy questions, send mail to: Jim Bacher at: j.bac...@ieee.org <mailto:j.bac...@ieee.org> _ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC <https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1> &A=1 - 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 All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: _ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
Re: [PSES] 2 simple questions on EMC
Hi BrianI have done a number of comparisons between 3 m and 10 m test distances at many labs. In almost every case below 100 MHz the 3 m case produces worst results. So it would be reasonable to assume that if you moved out to 10 m you would have a better passing margin. Additionally, I’d like to caution that heavy load doesn’t always mean higher emissions, it depends on what the source is. Further, a strong driver in emissions has been power line frequency. LED drivers in particular need to run at their design frequency, even though they can “work” at the other line frequency. We recorded 15 dB difference 50 Hz vs 60 Hz. Good luckDerek. Sent from my iPhoneOn Nov 1, 2023, at 12:53 PM, Ralph McDiarmid wrote:The EMC standard with which I am familiar (CISPR11, EN55022) are well written and provide examples of best practice setup and how to arrange excess cable length. I suggest going over the standard with the test technician at the EMC lab to better understand the requirement. If it were my product, I wouldn’t lose a minute’s sleep over a 1dB pass at a narrow range of frequency in the test spectrum, however, I would want to test at rated power. You may find that peak rises with increasing EUT power. Ralph From: Brian Gregory Sent: Tuesday, October 31, 2023 2:29 PMTo: EMC-PSTC@LISTSERV.IEEE.ORGSubject: [PSES] 2 simple questions on EMC Hi, 1. Our unit is passing by a whisker, under 1dB @ 30 Mhz in a 3m chamber against SubpartB requirements. Can we expect margin to improve in a 10m chamber? 2. It's lightly loaded in the chamber (10% of FL), we do expect the peak to squash down a bit with full load; they do when going from zero load to 10%. 3. We were idly wondering about cable loop; the output cable (bundled AWG #6) is 6' runs about 12" in front of the unit towards the antenna and the balance of it is currently coiled up in a loose bundle under the test setup. The standards don't say anything about cable routing, just that it should be on the ground plane. I don't like it running 'in front' of the unit, but the lab tech says that's pretty standard and not driven by the necessities of the test setup. Is that standard for a radiated setup? Colorado Brian 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 All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe)List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators:Mike Sherman at: msherma...@comcast.netRick Linford at: linf...@ieee.org For policy questions, send mail to:Jim Bacher at: j.bac...@ieee.org To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 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 All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher at: j.bac...@ieee.org To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 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 All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher at: j.bac...@ieee.org To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
