As per LHO WP 6501, this morning I temperature tuned the HPO pump diodes after last Saturday's pump diode current increase. I began by turning the ISS OFF and then proceeded to tune the HPO pump diodes' operating temperature. The old and new pump diode operating temperatures for the 7 diodes in each diode box are listed in Table 1 below.
| Diode Box 1 (°C) | Diode Box 2 (°C) | Diode Box 3 (°C) | Diode Box 4 (°C) | |||||
| Old | New | Old | New | Old | New | Old | New | |
| D1 | 25.5 | 25.0 | 20.0 | 20.0 | 22.0 | 22.0 | 24.5 | 24.0 |
| D2 | 26.0 | 25.5 | 19.5 | 19.5 | 26.0 | 26.0 | 22.0 | 21.5 |
| D3 | 28.0 | 27.5 | 20.5 | 20.5 | 26.0 | 26.0 | 23.5 | 23.0 |
| D4 | 24.5 | 24.0 | 18.5 | 18.5 | 23.0 | 23.0 | 22.0 | 21.5 |
| D5 | 26.5 | 26.0 | 18.5 | 18.5 | 27.0 | 27.0 | 24.0 | 23.5 |
| D6 | 26.0 | 25.5 | 19.0 | 19.0 | 21.5 | 21.5 | 24.0 | 23.5 |
| D7 | 23.5 | 23.0 | 19.5 | 19.5 | 22.5 | 22.5 | 24.0 | 23.5 |
In addition, I increased the current to DB1 by a further 0.2A to bring it closer to the other diode boxes; this diode box is starting to decay more rapidly than the others, so is likely to need replacement first. A summary of the old and new HPO diode box operating currents is shown in Table 2 below. The PSL HPO is now outputting ~169.0 W.
| Operating Current (A) | ||
| Old (pre-2/25/2017) | New (2/28/2017) | |
| DB1 | 51.0 | 51.7 |
| DB2 | 51.0 | 51.5 |
| DB3 | 51.0 | 51.5 |
| DB4 | 51.0 | 51.5 |
Following that, with the ISS still OFF, I then proceeded to tweak the beam alignnment into the PMC; only small tweaks were necessary to to maximize the transmitted power. With the ISS turned back ON, the PMC transmitted power is now 65.0 W and the PMC reflected power is now 14.0 W. This closes WP 6501.