Hello si-list, I have a question concerning hard disk immunity with respect to common-mode (CM) currents on it's cables, that is, what is the maximum limit (very likely frequency dependent) of CM currents on the power port and/or data cable. The CM currents are due to parasitic capacitive (or possible conductive) coupling between the hard disk and the chassis. The parasitic CM currents interfere with the disk operation during read/write operations, which use sensitive analog signals and are, as such, prone to intereference from these stray currents. I have seen specifications of CM current limits of amplitude versus frequency. In the past I have had a good repsonse from IBM people on this list. I was hoping that they or others could contribute some information on this topic. Kind regards, Jan Vercammen EMC/SI Engineering Agfa-Gevaert NV, Belgium ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu