EC150 post testing

10m.c (SN 1473) read high and 15m.c (SN 1390) read low during the project, so we want to know what is going on.  Some input:

• The edges of the lens on 1390 were cloudy when inspected in the lab
• In the staging lab, I fired up both along with SN 1494 which had been in the lab.  The h2o values were:
  • 1494: 8.68 g/m^3
  • 1390: 3.60 g/m^3 (5.08 lower than 1494)
  • 1473: 9.21 g/m^3 (0.53 higher; 5.58 higher than 1390)
• We just did the lab zero/span test.  During that:
  • 1473: zero 0.71 (3.33 higher than 1390); then zeroed
  • 1390: zero -2.62; then zeroed
  • h2o span is still in progress
• After the zero/span, repeating the staging lab test:
  • 1494: 7.98
  • 1390: 9.55 (1.57 higher than 1494)
  • 1473: 9.21 (1.23 higher than 1494 and 0.34 lower than 1390)

This seems to indicate that the zero/span process does actually change the output values.  Now I'm even more puzzled!  (As to why these sensors immediately had large offsets between the pre-SOS lab calibrations and the first data taken in the field).