If you are trying to do an A-B comparison between two filters or simply characterize at different impedances, it is possible to use a 10:1 BALUN in line with your spectrum analyzer and tracking generator setup to intentionally introduce a mismatch in impedance. I recommend doing three measurements. 1) with no BALUN or a 50/50 Ohm balanced match. 2) with BALUN on the filter input in one direction or a 5/50 Ohm mismatch 3) with BALUN reversed giving a 500/50 Ohm mismatch.
All this should be done with the test setup and the filter under test well bonded to a single ground plane. Obviously, this still does not emulate the "real world" but it may give you enough data to get a better understanding. As already mentioned, in situ is ultimately the best way to go. All the best, Doug Douglas Powell http://www.linkedin.com/in/dougp01 Original Message From: John Woodgate Sent: Wednesday, April 15, 2015 7:59 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Reply To: John Woodgate Subject: Re: [PSES] Schaffner net filter FN 2080 In message <64D32EE8B9CBDD44963ACB076A5F6ABB026D936A@Mailbox-Tech.lecotech.local>, dated Wed, 15 Apr 2015, "Kunde, Brian" <brian_ku...@lecotc.com> writes: >You may just want to characterize the line filter yourself. Then you >will know. You will need a receiver or spectrum analyzer with a >tracking generator, a network analyzer, or a sig gen and power meter >combination. Our lab uses a simple labview program for characterizing >amps, filters, cables, attenuators, LiSNs, etc.. Every lab should have >something setup to do this fairly quick and easy. Such systems do not normally model well the actual source and load impedances seen by the filter when in service. Some filters are less sensitive to these impedance effects than others, but above the specified bandwidth, that may not be so. Ideally, one would measure in situ in the product, feeding a current (through a high impedance) in and measuring the voltage (with a high-impedance device) out. But it may not be easy to do that now. In the old days, we would get high impedance RF probes with most RF instruments, but, while much easier to make now, they seem to be anomalously rare. 50 ohms rules - not OK. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - ---------------------------------------------------------------- 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> - ---------------------------------------------------------------- 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>