Dries, it sounds very much as if that short shield is acting as a (low-value) bypass capacitance. If, as you say, no shield is permitted, then your customers will audit with no shield, and the product will fail no matter what "tricks" you used to get around failure in your own tests. Then you will still have to deal with the problem - and explain to your bosses how you let it get by. If you are lucky! Avionics problems have a way of turning serious 10 km up. Don't do it.
It's best to fix the problem inside the equipment. This could be as simple as 100 pF or so capacitance from each conductor to chassis (what, I think, that short shield is doing) or a bifilar common-mode filter optimized for the frequency range you are currently failing. Cheers, Cortland Dries Vanduffel wrote: >> 'm measuring RE02 according Mil Std 461C. the Standard says that 'signal cables' have to be at least 2meters long lay and on the table. My cables are twisted pairs and not allowed to be shielded. Around 30MHz I get hugh outages. The total cable length is 3 meters (this length is only chosen to reach the wallplate). When I shield off the last meter from wallplate towards the table with Alumium foil, the outages decrease drastically and my equipement is 'almost' passing the test. (around 20MHz - 30MHz outages have to stay below 20 dbuV/m!!!) My question: Is this a legal trick to pass RE measurements? and if so: Is it also allowed to actually connect this artificial shield to the table (gives best result) or should it just stop there and not touch the table? << 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
