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
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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>>
