A fools paradise or not I don't know but to say that it is only secondary circuits that radiates is not true. I have several switch mode power supplies which have radiated emission up to 150MHz. Especially from 40 - 100MHz I often see problems. This emission is normally very sensitive to the power consumption/input current. But you are right a step from 115 to 230 V don't make that big different but a change from 200 to 240 can. As I see it, it is the current flow arround switch transistor - bridge - transformer which are the main problems. Transistor and transformer is normally not affected by 115/230 but what about the first bridge ? here the current will change by a factor 2 ! or am I wrong ?
Best regards, Mr. Kim Boll Jensen ScanView, Denmark ---------- Fra: gmcintu...@packetengines.com[SMTP:MIME @INTERNET {gmcintu...@packetengines.com}] Sendt: 7. juli 1998 04:05 Til: hmellb...@aol.com; dwight.hunnic...@vina-tech.com; emc-p...@ieee.org Cc: eric.lif...@natinst.com Emne: RE: Ce versus FCC -------------------------------------------------------------------------- -- That's interesting. The change from 50 to 60 Hz would change some input components and that could effect the input impedance and hence the conducted emissions signature but the voltage, especially if its a well regulated and filtered supply should be invisible. The components that radiate at that point are all of the secondary 5 or 3.3 volt oscillators and stuff. They shouldn't even know the difference in the input voltage. If using a switcher power supply it seems even more odd. The input voltage is rectified and then chopped to "#$@ then more regulating and filtering stuff happens. Then it hits the electronics. Anybody else see this and have an idea why it might. I may be living in a fools paradise here. Gary McInturff Packet Engines -----Original Message----- From: hmellb...@aol.com [SMTP:hmellb...@aol.com] Sent: Monday, July 06, 1998 11:16 AM To: dwight.hunnic...@vina-tech.com; emc-p...@ieee.org Cc: eric.lif...@natinst.com Subject: Re: Ce versus FCC I have encountered certain European agencies requesting that not only are the conducted emissions required to be performed at 230V 50Hz but radiated emissions as well. I agree that for conducted emissions it may make a difference but I have not seen radiated emissions change when the power source is changed from 60 to 50 Hz (while keeping Voltage the same). I did, however, see recently a product change emissions when the voltage was changed from 120 to 230 V. And, it did not matter if it was 50 or 60 Hz, only the voltage was significant. Go figure! Hans <<Fil: ENVELOPE.TXT>>