Ghery, If the standard is assuming a 50 Ohm system, doesn't this breakdown to a simple calculation?
Insertion Loss = IL = 20 x log((50 + Zf) / 50)----where Zf is the ferrite impedance This could easily be solved for Zf if you assume IL to be 15dB (in this case the dB are truely dimensionless; as you are calculating a pure loss from an arbitrary level). I would think that you would just have to: 1. Solve the above for Zf. By the way, I get 231.2 Ohms. Can someone check this? 2. Gather up a box of "doughnuts" such that the total Zf is above the answer for step 1 at all frequencies from 30Mhz to 1Ghz 3. Color code the doughnuts (or whatever) and write a procedure that says something like "clamp three blue doughnuts and two red doughnuts over each cable ..." Have I over simplified this??? Wouldn't this be proof enough for any accreditation body? I know that $300 may not seem like alot to some; but it adds up after a few cables. Besides; we went to college to learn all of that math; why not use some of it? I don't mind paying for stuff that I can't make; but this one seems possible to me. 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: Pettit, Ghery [SMTP:[email protected]] > Sent: Wednesday, January 29, 2003 11:59 AM > To: '[email protected]'; [email protected] > Subject: RE: EN55022:1998 + A1:2000 > > > Amendment 1 to CISPR 22:1997 (Amendment A1:2000 to EN 55022:1998) requires > that the clamps provide at least 15 dB of loss in a 50 ohm system over the > frequency range of 30 MHz to 1000 MHz. The use of extension cords is > prohibited. Can you guarantee that your bucket of doughnuts will meet this > requirement? How will you demonstrate that to your lab's accrediting body? > > > Fischer's clamps are around $300 each. Compared with what we had to choose > from prior to their product, these are not big bucks. > > Ghery Pettit > Intel > > > > 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: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
