Can I ask, please? How do you verify that these support PC's actually fail to meet class B emissions?
Do you test them when you first remove them from their packaging, before adding your interface and peripheral? In my experience PC manufacturers qualify their PC's by creating the famous 'typical' system. What is a 'typical' system? Most interfaces also require their own certification, however, again they tend to be qualified using a 'typical' peripheral arrangement. One of the main problems is that a peripheral/interface may be qualified using 'typical' systems x, y, z but that does not mean that typical systems a, b & c will pass. To some extent this brings us back to the subject of margin. If the PC manufacturer tests his PC in a number of 'typical' system arrangements and sticks to a decent margin, say ~6dB, and makes use of the 80-80 rule then it might be fair to say that his PC is reliably compliant. So, is your PC non compliant or have you found one of the non compliant arrangements? I believe that the governing bodies are well aware of this and tend to be more interested in knowing how much interference your part of the system introduces, both directly and indirectly. Peter --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
