[Richard, Fil, Kawabe, Marc]
See ALOG 31948
Replaced I&Q Demod Chassis (D0902796) S1000977 with S1001002. We removed the 0 ohm bypass resistors from channels 1 and 2 and installed filters from the old chassis into the new chassis.
Channel 1 = MCL PLP-21.4+ (21.4Mhz Low Pass Filter)
Channel 2 = MCL PHP-100+ (100MHz High Pass Filter)
This new chassis also had the power supply cable installed upside down, we fixed this. The +15V LED lead was not fully seated into the connector housing, we fixed this as well.
We do not have spare filters in stock or we would have replaced these, Fil will order some replacements.
LO monitor level increased by about 0.7dB for POPAIR_B 19 and 90, but not that much for REFLAIR_B 27 and 135, ans as a result POPAIR_B_RF18 was vommiting an error (H1:LSC-POPAIR_B_RF18_DEMOD_ERROR_CODE) and POPAIR_B_RF90 was close. I just increased the nominal LO level by 1dB and accepted in SDF for safe.
H1:LSC-POPAIR_B_RF18_DEMOD_LONOM=23 (was 22)
H1:LSC-POPAIR_B_RF90_DEMOD_LONOM=21 (was 20).
This chassis served POPAIR90, POPAIR18, REFLAIR27 and REFLAIR135, so I have re-set the demod phases for all of these. The POP 18 & 90 I adjusted the phases to maximize the I-phase signal while in DRMI_LOCKED. The REFL 27 and 135 I adjusted also in DRMI_LOCKED, so while we're locked on these 3f signals, by driving PRM in length at 132Hz and minimizing the line in the Q-phase.
I also redid the dark offsets for these channels (although the REFLair ones will get set every acquisition), as well as for AS90 which looked like it needed it.