aLIGO LHO Logbook

H1 ISC

richard.mccarthy@LIGO.ORG - posted 07:12, Thursday 23 March 2017 - last comment - 16:03, Thursday 23 March 2017(35033)

H1 Harmonic Frequency Generator Swapped

After a night of wasted science, (45Mhz Glitches) the Harmonic Frequency generator was swapped.  Hopefully this was the culprit causing the glitches in the RF45.  Serial number S1000796 was replaced with S1000798
Work Permit 6537

Comments related to this report

daniel.sigg@LIGO.ORG - 09:01, Thursday 23 March 2017 (35038)

Link

RF demodulation phases for 2f, 3f, 4f, 10f and 15f might change with this swap.

richard.mccarthy@LIGO.ORG - 13:09, Thursday 23 March 2017 (35045)

Link

Replace Attenuator on:

Freq  Value with 
18MHz +3    +2
27MHz +6    +2
36MHz +5    +4
45MHz +2    +1

91MHz 137MH No change.
To keep the input value at 10dbm.

Values based on Epics readbacks.

jeffrey.kissel@LIGO.ORG - 16:03, Thursday 23 March 2017 (35049)CAL, DetChar, OpsInfo

Link

Tagging DetChar.

We've recovered nominal low noise after this swap -- how ever we're seeing a lot of different behavior within this first few minutes:
 - Some line features below 100 Hz are reduced
 - There is elevated 500 Hz rising as f (like shot noise) noise floor
 - Occasional comb in a similar region
 - 4-5 kHz ratty hump that comes and goes
 - incredible amount of omega glitch above 500 Hz

Just letting you know to keep your eyes peeled that this swap may mean several significant changes to the IFO that we may have to continue to rectify and/or deal with.