Attached are ASD and Coherence betwix the three corner station STS2s taken at 3am local Wednesday Thursday and Friday.  These three days look very similar.  I installed STS2-A aka HAM2 on Tuesday.  Recap:

STS2-C (HAM5) has been in place for long time.  STS2-B (ITMY) is the unit returned from Stanford replacing PEM STS2 which we were using to replace our original STS2-B which is still at Quanterra for repairs.  STS2-A returned from Quanterra after a couple months in their vault where they say there was no problem.  The A unit spent time in the BeirGarten near the ITMy unit undergoing cable and chassis swaps, see 18354 for recap but nothing was consistent.

To me, STS2-A still looks like this unit has a problem.  When I look at plots from back in May, 18354, it looks even worse now.  There was better coherence in Z and X with the other units and Y was equally poor.

RobertS--do you have an opinion?