In message <[email protected]>, dated Tue, 7 Nov 2006, Kim Boll Jensen <[email protected]> writes >I have a passive cable TV distributor box which connects a coax TV >antenna signal to a Ethernet cable system (1 pair of 4 used). The >product shall be tested according to EN 50083-2 as fare as I can see, >but the problem is that the Ethernet cable is 100 ohm and the standard >tests at 75 ohm terminations. > >Have I overlooked any standards or special requirements or can I just >test the product for screening effectiveness according to the standard >with 75 ohm terminations.
You may get a seriously wrong answer if you do. The 100 ohm is balanced, isn't it, but the 75 ohm is unbalanced. So you need to connect between the Ethernet pair and the 75 ohm termination a screened balun transformer that converts 100 ohm balanced to 75 ohm unbalanced. You need to take into account the insertion loss of the balun transformer. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Swine wave - a waveform whose spectrum is exceptionally difficult to calculate. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
