How about the different size loops the ground leads on your probes are making.
*Dale Reid* Product Safety Engineer *O* +1 859 825 4733 [email protected] <http://www.lexmark.com/> www.lexmark.com On Sun, Jan 28, 2018 at 7:54 AM, Bart De Geeter <[email protected]> wrote: > Hi Doug, > > > > Could it be that there is just a piece of transmission line > inside the box terminated with a certain impedance? You might be measuring > in the middle of this transmission line. > > If the input impedance selected on channel A of your oscilloscope is f.e > 50 ohm and the other input channel has 1Mohm input impedance selected, you > will measure a different voltage at this particular point (as the measured > signal is the sum of the direct wave+ reflected wave on this transmission). > > > > So far, my guess 😉 > > > > Greetings, > > Bart > > > > *Van:* Doug Smith [mailto:[email protected]] > *Verzonden:* vrijdag 26 januari 2018 23:50 > *Aan:* [email protected] > *Onderwerp:* [PSES] Measurement dilema > > > > Hi All, > > Can you explain the result in this video I just made? Scope plots of the > same two nodes are completely different. Probes and scope are operating > normally, no problem with the equipment itself. > > If you have been to my seminars you know the answer, please do not post > the answer unless you have not seen this experiment until now. > > Hint 1: There are no EM fields radiating from the shielded box affecting > the probes. > Hint 2: There are no active components inside the box. > > https://youtu.be/qj-HBFMEJiY > > Doug > > - > ---------------------------------------------------------------- > > 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 < > [email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - > ---------------------------------------------------------------- > > 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 < > [email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
