Dear John Sorry to be so late replying. I am pleased that you now understand the situation that I attempted to describe earlier, where an HCMOS inverter with an unterminated input was the cause of surprisingly powerful radiated emissions at 200MHz, due to an unfortunate, unlikely, but not impossible combination of events.
All the very best! Keith In a message dated 14/01/02 18:54:00 GMT Standard Time, [email protected] writes: > Subj:Re: EMC-related safety issues > Date:14/01/02 18:54:00 GMT Standard Time > From: [email protected] (John Woodgate) > Sender: [email protected] > Reply-to: <A HREF="mailto:[email protected]";>[email protected]</A> > (John Woodgate) > To: [email protected] > > I read in !emc-pstc that [email protected] wrote (in <14b.7351131.297 > [email protected]>) about 'EMC-related safety issues', on Mon, 14 Jan 2002: > > I'm sure I said in my original posting on this example, that the HCMOS > was > > 'hard switching' and not producing a sine wave. A hot device was, of > course, > > the first thing I looked for, and didn't find any. See the additional > > information above. > > > Yes, you did, BUT I wrote: > > > > > > > The absence of harmonics even suggests that this gate was producing > a > > > sine-wave, which makes the figures even higher and less credible. > > The presence of the high-Q resonant structure that you describe is > clearly the real reason why no harmonics were observed. It is not only a > good antenna *but it very probably cannot radiate odd harmonics*, which > should be the only ones present if the drive waveform was square. > -- > Regards, John Woodgate, OOO - Own Opinions Only. > http://www.jmwa.demon.co.uk > After swimming across the Hellespont, I felt like a Hero. >
