Charlie, FCC Class B "protection distance" is 3m, where Class A is 10m. This establishes their relationship. Class B = X dBuV measured at 3m, and Class A = X dBuV @ 10m. (where X = X)
>EN 55022 Class B is for domestic environment which is "an environment where >the use of broadcast radio and television receivers may be expected within a >distance of 10m or the apparatus concerned". --------------------------------------------------- Rick, AM is older than the FCC, but they are making noise (pun intended) about revitalizing it. https://apps.fcc.gov/edocs_public/attachmatch/DOC-323370A1.pdf While LEDs are quiet, any mains powered LED lamp involves some form of pulsed current and EMI. LED lamps are regulated under FCC Part 15. I tried to use them (LED floods) in my shielded enclosure with dismal results. For those interested; This article is mainly about visual flicker, but the same principles apply to noise generation. http://www.digikey.com/en-US/articles/techzone/2012/jul/characterizing-and-minimizing-led-flicker-in-lighting-applications Here's a discussion of the RFI problem more from a regulatory perspective. http://www.emcrules.com/2011/07/radio-interference-from-led-lighting.html -Bob Sykes -----Original Message----- From: Rick Busche [mailto:rick.bus...@qnergy.com] Sent: Wednesday, June 04, 2014 1:26 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] radiated emissions testing may understate actual emissions, an example using a class D stereo amp Do we still have AM? Someone once called that was Ancient Modulation. :) I suspect that in a few years fluorescent lamps will give way to LED technology. As a side note, do LED lamps create EMI concerns? -----Original Message----- From: Richard Nute [mailto:ri...@ieee.org] Sent: Wednesday, June 04, 2014 11:02 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] radiated emissions testing may understate actual emissions, an example using a class D stereo amp On 6/4/2014 9:47 AM, Mike Violette wrote: "Class B limits are amazingly conservative, to which large populations of devices ascribe." Try using an ordinary AM radio beside a compact fluorescent lamp as on a beside table. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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