Hi Joe, I made a homemade LISN using a schematic from Clayton R Paul's book. Our company also bought a pre-compliance LISN from Wayne Kerr. In my experience, both are good enough for pre-compliance work.
My "calibration" is done by measuring products that were previously tested at an outside lab. I compare my actual results with thiers. The only bad part about this is that you need a product with a failing or near failing emissions profile to get a good "comb" of data for comparison. Fortunately we had a power suppy about 4 years ago with a 150Khz switching frequency and a slightly failing emissions profile. It produced a beautiful set of harmonics at the lab. So, I calibrated my setup while I troubleshot this power supply. This comparison gives me a rough confidence factor in the setup. No it's not a calibration sticker; but I'll take an actual comparison over a cal sticker any day. I second Michael's opinion regarding the isolation transformer. Our measurements were erroneous and noisy (the copier in the other room produced so much conducted noise that I couldn't see anything from the DUT) until I bought an Isolation Transformer. We bought a Panel Components part # 82520030. It has served us well. It offers the option to wire it up for a 2:1 ratio, so I use it to create 230VAC for European products. I would also like to add that I use our ESD bench as a pre-compliance conducted emissions setup. It already has a ground plane. I tie the LISN's ground to this plane as a reference. Seems to work well. So I guess that a hunk of metal for a ground plane is a recommended purchase. Other items that have proven to be valuable are various line cords with ends cut and stripped. These can be used along with wire nuts to quickly allow your LISN to test products with different line cords ... There are tricks to wiring ground through the isolation transformer, wiring DC through your LISN (for DC products) ... it doesn't take a great deal of money or time to set up for pre-compliance. Have fun and don't kill yourself!!! Chris Maxwell | Design Engineer - Optical Division email [email protected] | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | > -----Original Message----- > From: Peters, Michael [SMTP:[email protected]] > Sent: Thursday, November 29, 2001 8:58 AM > To: '[email protected]'; [email protected] > Subject: RE: LISN Calibration > > > Joe, > > For piece of mind. The LISN provides repeatable results for different > line > impedances. Making sure that the LISN impedance is what it is > supposed to > be and the insertion loss is satisfactory will give you a better > comfort > level when going to the test house. > > If you have not already done so, I would recommend an isolation > transformer. > Many factories and office buildings have a great deal of ambient noise > that > will interfere with your measurements. > > If you have an s-parameter network analyzer (that works from 150 kHz > to 30 > MHz), the calibration is not too difficult to perform and there is a > procedure outlined in ANSI C63.4 that is easy enough to follow > (although for > impedance it doesn't mention you need an RF splitter). > > Good Luck! > > Michael Peters > [email protected] > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] > Sent: Wednesday, November 28, 2001 7:16 PM > To: [email protected] > Subject: LISN Calibration > > > > We are in the process of setting up a pre-compliance EMC lab. One of > the > tests that we will be performing is pre-compliance conducted emissions > per > EN 61326. > > I realize that since we are only performing pre-compliance > measurements > that calibration of the LISN is not required. However, do you > recommend > calibrating the LISN for pre-compliance measurements? If so, why? > > Your responses are appreciated > > Regards > > Joe Martin > Applied Biosystems > > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the > old > messages are imported into the new server. > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the > old messages are imported into the new server. ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
