The frame builder is timed from the Symmetricom GPS card now, which is getting the IRIGB timecode from the freq. distribution amplifier (from the VME GPS receiver card).
I have adjusted the GPS seconds to match the real GPS time and the DTT seems to be happy: sweeping MC2 MCL filter module produces nice plot.
Test points are working on SUS.
Excitations are working on SUS.
I am leaving the frame builder running and acquiring the data.