Andre: I suspect your generator has a problem, however, I would not blame a high-impedance oscilloscope as the likely cause. First, because an oscilloscope should not be putting any signal back out of its input port. And second, because a signal generator should be designed to expect any terminating impedance from 0 Ohms to Infinity, and to survive the resultant reflected power without damage.
However, any number of things may be wrong with your generator. It may have a damaged output attenuator, a damaged output stage, it may be being commanded to create some wildly different frequency or it may have digital brain problems. It might even be your cabling, so cross-check everything. BTW, fancy newer equipment may have the display "tied" to the internal computer more than to the actual output. By that, I mean that a display may be "listening" to what the computer tells it what the operator has selected rather than actually sampling the output on its own. (On any stimulus device, you should be intimately aware of what is really being measured and displayed.) To assure yourself, also be sure your oscilloscope passes a self-test and also reads correctly when connected to a known-good third device. The same should be done for your generator, by connecting a wide-band detector to the output and being sure that there are no strange and/or large emissions present. It's possible that it was just time for something to fail inside your generator, but if you find a blown component, then you may want to trace and check everything which that generator has been associated with since it's last known good operation. Ed Price WB6WSN Chula Vista, CA USA From: Andre Gomes Videira [mailto:ago...@weg.net] Sent: Thursday, May 17, 2018 6:18 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Doubts on RF generator problem Hello all, I would like your opinion on one matter that happened in my lab not long ago. I found out that my RF generator was sending a much lower power than it was specified. If on the display it was described as it was generating 0dBm, the real output power was around -50dBm. I also found out that, one of my co-workers, previous to this problem, had connected the RF output (with 50hm of impedance) to an oscilloscope (with 1Mohm of impedance). Of course, this means that I had a full signal reflection on this case. The signal was around -20dBm in 35kHz. Should I assume that my generator is damaged? Or maybe I have another kind of problem, and this connection and reflected wave do not pose a threat to the generator? Thank you very much for your help. Best regards, André Gomes Videira Laboratório de Ensaios e Certificações Telefone: + 55 47 3276-7613 | Skype: agvideira WEG Drives & Controls - Automação Ltda. www.weg.net Clique aqui <http://disclaimer.weg.net/> caso você não seja o destinatário deste email, ou desejar conhecer nossa política de privacidade. Click here <http://disclaimer.weg.net/> if you are not the intended recipient, or in case you want to know our privacy policy. - ---------------------------------------------------------------- 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 <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> 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 <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> 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 <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
