Thanks for all the responses and I'm hope I'm not too green for this = list.=20 Like I said in the previous post I'm new to this GHz stuff but I'm very = resourceful. I wanted to answer a couple of questions and further = clarify.=20 First I was asked if I had simulated the artwork. The answer is no. We = don't have that capability currently. But knowing I'm not simulating, I = design the artwork VERY conservatively. The I/O connectors are surface = mount serial ATA connectors. There are no vias, just a fairly straight = (~5") shot to the Virtex II Pro chip. The corners are well rounded and = the spacing between traces and the ground plane were set by the fab = house at 100ohm differential impedance. Crosstalk should not be a = problem as all other signals have been kept far away. For the TDR I was planning on building a launch PCB with coax connectors = matching the TDR module to a serial ATA connector. I was going take a = blank PCB and stuff only the serial ATA connector and connect it to the = launch PCB with a serial ATA cable. Is there a flaw in my thinking?=20 I will study up on the TDT. =20 My overall thinking on this first try at a mulit-gigabit design is to go = very conservative. Use hardware that is specified for higher than these = frequencies, keep everything shorter then designed for. With limited = funds for test gear I have to do some finger crossing. I'm trying reach = a balance between the finger crossing and buying all the test gear I = really want. Ray Haynes Phoenix, AZ ------------------------------------------------------------------ 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 technical documents are available at: http:/www.si-list.org 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