Peter: Although "the customer is always right" generally applies to retail sales, it sounds like he/she is creating major problems with the stated cable configuration. The most common use for triaxial (otherwise known as double-shielded) cable is for increased isolation/shielding for both radiated emissions and susceptibility. You are right to be concerned about the common-mode voltage conversion that will result from the triaxial cable being driven from a differential source. The result will undoubtedly be an increase in EMI (radiated emissions). Depending on the frequency content of the signal (which you failed to mention), the use of a twisted, shielded pair (TSP) would appear to be a superior choice from both the technical and cost points of view. Many TSP designs are closer to 100 Ohms, but there are probably multiple sources for lower impedance TSPs. The stated differential impedance of 75 Ohms for your PCB might also be changed to 100 Ohms which would more closely match widely available, low cost TSP cable. If the 75 Ohms is related to TV or other communication circuits, I would expect it would be single-ended, not differential, in nature; therefore, a different approach altogether may be in order. I can't comment further with the limited info you provided. Mike Michael L. Conn Owner/Principal Consultant Mikon Consulting *** Serving Your Needs with Technical Excellence *** ------------------------------------------------------------------ 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