[Murtaza, Paco, Radhika]

After the input beam path alignment was complete (arm flashing recovered), we attempted to run Yuta's beam centering measurement script (scripts/ASC/measureALLBeamSpotPosition.py). I was able to align and lock the arms at low power following the procedure here. The resulting ITM/ETM beam mis-centering measurements can be seen below.

Next I struggled to lock MICH to measure mis-centering on the BS using Yuta's instructions. We noticed the AS beam was clipping horizontally. Paco and I aligned the AS beam using SR2/AS1 and the beam now appears unclipped. We found the demod angle that minimized AS55_I to be 86.56 deg, not far off from Yuta's value. We mananged to lock MICH with: 1. ASDC trigger matrix element: -30; trigger threshold lowered to -0.5 (enable). We then obtained the BS mis-centering measurement below. Note that the uncertainties here are on the order of the mis-centering value.

Attachments 1 and 2 compare the vertical and horizontal beam mis-centering values before and after the in-chamber alignment. In summary, beam spots on ETMs and ITMs have more or less converged towards center vertically (BS is the exception). However, the beam spots seem to have diverged horizontally from center. This means our pitch corrections were in the right direction, but we'll need to take measurements on PRM/PR2/PR3 to confirm this. It seems like trying to mitigate horizontal clipping at PR3 has propagated mis-centering downstream.

Measuring the beam spot on PRM/PR2/PR3 requires PRY locking, but it seems that little to no light is hitting REFLDC or any of the RF REFL PDs. This will be debugged next.

[Koji, Paco, JC]

The door of the Input Chamber Has Been Removed



We removed the chamber door off of the input chamber. Koji and Paco worked on removed the bolts while I was preparing the crane for use. When removing bolts from the chamber doors, we were careful not to remove them all at once, Koji decided to leave 4 loose bolts remaining until the crane has a tight lift on the door. 

As for the crane, to remove this door, we needed to extend the swing arm out. The crane itself JUST BARELY makes it over to where the hook can hover nicely over the door. Next, I lifted the door until the sling was nice and tight. Then Koji process to remove the 4 bolts holding the door in place. We lifted the door all the way up and slowly swung the arm to bring the door by ITMX Chamber. Here, we lowered the door and placed it flat onto a Piano Dolley. The door is now wrapped in AntiStat and laying flat onon a piano Dolley by the ITMX Chamber. 

Radhika reported that the PRM UL OSEM PD is not responding. This PD has been identified to have a shorting problem, but the short existed only at the bias pin of the PD. We disconnected the bias voltages and the PD was working with no (=0V) bias.

It seems that it lost the signal about 8 days ago and the signal intermittently appeared and disappeared.

I suggested to Radhika to remove the Al foil suspecting the other pin of the PD is not shorting.

[Paco, Vittoria, Radhika]

Yesterday and today I noticed that REFLDC/REFL RF PDs sense verry little light, under 0.02 counts [Attachment 1]. We opened the table with REFL PDs and observed the beam, trying to steer it onto REFL55. No increase in counts was observed. The optical response of REFL55 was verified by shining a flashlight on it (reached 2 counts). We tried touching the RF PD box and wires to ground them in case there was some weird electrical response. The counts did not increase on the PD. 

We then borrowed the power meter from the PSL table to measure the REFL beam power in watts. Oddly, measuring the beam as upstream as possible (before all the beamsplitters) only recorded 5 mW of light. This was bizarre, since by eye the beam is quite bright on the beam card. Such low power would explain the PDs not picking up the light; Koji theorized that it might be a ghost beam and the actual REFL path might be blocked inside the vacuum volume. On the other hand, PRM alignment shouldn't have changed that much to result in a misdirected REFL beam. We will investigate tomorrow.

Task Completed Today :

• D2200122 Spacer Rings have been machined and ready for C&B
• The North siderail of the cleanroom has been raised.
• Parts SM05RR, LMR1V, D2300352-01, -02, -03, -04 have been C&Bed.
• A New Cart has been Cleaned and added for working purposes to the cleanroom

D2200122 Spacer Rings have been machined and ready for C&B

I walked over to the GALCIT Shop today after receiving an email notifying me that the Spacer Rings are ready. We received 5 rings instead of 4 because the machinist made a mistake on one and was a couple thousanths of an in thicker. This ring is marked red on the photo in attachment #1. I have given these rings to Maty and she will take care of the C&B process since I will be out tomorrow. She said she expect them to be done sometime early next week.

The North siderail of the cleanroom has been raised.

I raised the North Siderail of the cleanroom to give us some more freedom moving the steel cart around in the cleanroom. This also allowed me to rotate the cart and add a bit more space inside. While doing this I had the particle counter running and 0.5 Micron count < 50 and the 0.5 Micron count < 10.

Parts SM05RR, LMR1V, D2300352-01, -02, -03, -04, and D2300208, D2300209, D2300210 have been C&Bed.

SM05RR, LMR1V, D2300352-01, -02, -03, -04, D2300208, D2300209, D2300210 are ready as of today. These have been placed in a plastic box on the middle space of the newly added steel cart. The Plastic boxes have the DCC/Part number on top so you will know what parts are inside.

A New Cart has been Cleaned and added for working purposes to the cleanroom

I brought the steel cart over from the shed area. I thoroughly wiped it down with IPA after cleaning with Windex and a rag. I also used the air gun to blow of any heavy dust from the wheels. I placed foil over each level of the cart and wiped down again with IPA. After, I made some AntiStat curtain around the cart to keep out anything heavy. Here are the plastic boxes containing parts SM05RR, LMR1V, D2300352-01, -02, -03, -04, D2300208, D2300209, D2300210.

Today Yuta and I opened the BS chamber and found that the REFL beam was misaligned in pitch and yaw [Attachment 1]. We steered PRM until REFL and input beams overlapped [Attachment 2]. From there, we moved PRM around until we recovered the REFL beam on the camera. This means bright REFL (prompt reflection from PRM) is aligned onto the AP table. Now some steering mirror alignment on the AP table should recover REFLDC/REFL55 signal response.

Lastly we removed the foil caps on the PRM face OSEMs (before/after in Attachments 3,4). We noticed the SD OSEM foil cap had already fallen off. 

Momentarily PRM UL sensor counts returned, but then went back to 0. We couldn't see any shorting and then gently touched the top two sensors to see if counts would return. No luck.

I took over the IFO after Radhika left. She found the REFL beam earlier and the PRM alignment offset for the refl beam on the refl camera was (P,Y)=(469,2558).
When the REFL11I responce is maximized to be -6 (presumably because of the RF residual AM), (P,Y) was (379,2548).
When the PRMI fringe like feature shows up in the AS camera, (P,Y)=(429,2028).
I left the PRM at (469,2558), so that the REFL spot is obvious on the REFL camera.

The PSL shutter was closed at the end of the work.

I went through the inventory list and the parts in hand to figure out what was still missing

The list was made on E2200464, and the PDF snapshot was added to this entry.

Resolved

• 2" pedestal post with a bottom vent hole (QTY 1+spare 1) 1 in hand / to be drilled / to be C&Bed
• 2.5" pedestal post with a bottom vent hole (QTY2+spare 1) 2 in hand / to be drilled / to be C&Bed
• Thorlabs NB1-K14 mirror (QTY1 + spares 3?) 2 in hand
• Need to find 5 Y1-1025-45P collected various 45P mirrors. In principle we have all.
• Faraday Rotator Riser D2200378 (Already ordered by Don) To be delivered / To be C&Bed
• D2200122 ring spacers (Coming in soon from Caltech machining shop)
  -> They are ready for C&B on Nov 16 (JC)
• Polaris-K1-2AH on the flow bench in the C&B lab. 

Unresolved

• PDR1V rotation stage -> in search

[Yuta, Vittoria, Radhika]

PRMI flashing recovered; haven't yet been able to lock PRY

This morning the recovered REFL beam was steered onto REFL55 to maximize the REFLDC signal to 1.4 (consistent with around a factor of 10 laser power reduction).

Since PRMs alignment was changed a lot to recover REFL beam, we noticed that light was no longer hitting the PRM oplev QPD. was no longer detecting any light. We moved onto recovering PRMI flashing:

- Radhika and Yuta moved PRM around until they saw flashing at the antisymmetric port

- REFL DC read 1.4 counts, and then PRM was aligned to drop it to 0.3 counts

- While in this state of good alignment, Radhika and Vittoria went inside and centered the REFL beam on the camera

- We checked that the REFL beam was centered on the REFL RF PDs

- Then we moved on to OPLEV centering for PRM

- Then we identified the PRM QPD and couldn't find the beam

- We traced back the beam and found that it was hitting the bottom, plastic part of an optic

- We adjusted one of the steering mirrors of the input OPLEV beam so that it hit the mirror it was initially clipping on

- Then we moved around two steering mirrors to center the OPLEV.

[Yuta, Radhika]

PRY locked and PRM/PR2/PR3 beam spot positions measured

We aligned the arm cavities and locked at low power, then measured beam spot positions on ITMs and ETMs to verify nominal centering.

Moving onto MICH locking, we noticed what could be AS beam clipping in pitch. We struggled to lock to dark fringe and measure a reasonable beam spot position, so we decided to move onto PRY since we already had a BS spot measurement.

We restored PRM alignment and brought it back to rougly center of the camera. PRCL started to flash and we aligned PRM to until REFLDC flashed down from 1.5 to 0.3. Next ITMX was misaligned by 1500 cts so that it wouldn't contribute to AS fringing. REFLDC flashed down to 1.3 cts at this point, and we were able to lock PRY [Attachment 1] with REFL55 demod phase: 166.02; PRCL gain: -0.4.

Beam spot positions for PRM/PR2/PR3 are below and plotted in Attachments 2, 3. Attachments 4,5 are reposts of the beam spots for ITMs and ETMs. Overall, vertical mis-centering was generally reduced across optics (except for a slight overcorrection in PRM and worsening in the XARM). Horizontal mis-centering was generally made worse in most optics, while reduced in PR3 (magnitude). We plan to open the chambers to verify by eye that the beamspots are where we expect, and we may have to make some adjustments according to the measurements. It could be that the references used at PRM/PR2 were not actually reliable, e.g. oplev beam height. 

• PDR1V rotation stage was found
• 2" pedestal post x Qty 1 / top and bottom vent holes machined -> to be C&Bed
• 2.5" pedestal post x Qty 2 / top and bottom vent holes machined -> to be C&Bed

Vertex is extremely hot. I'm reluctant to go into the HEPA with clean garbings....

It seems that it started about a week ago. So this is not related to the holiday.
(Although I don't know where the sensors are)

- Setup the fiber protection and stray beam shields
- Replaced brand new wedged Y1-45P mirrors used in the OMC input path with stock Y1-45S mirrors. The wedged Y1-45Ps are going to be used for the optics on the BHD platform.
  Note: 45S mirrors are the same as 45Ps, but just their coating precision was not enough for 45P. So most of the cases 45S is sufficient for 45P purpose.
- All the remaining mirrors / CCDs / a lense / an RF PD (PDA-10) were setup and aligned.

- Found a DS345 is broken. The sinusoidal output does not swing and only has weird constant offsets dependent on the setting ==> need fix.

- An old analog function generator was brought for laser PZT scan test.
- Fast PZT cavity scan test: fine alignment & prelim visibility: REFL PD DS unlocked 5.50V vs TEM00 230mV -> estimated mode matching 95~96%
- When the OMC was detached from the kinematic mount and returned to the position: Relection at TEM00 230mV -> 1V. This corresponds to ~15% degradation of the alignment.
- OMC retainer screws (white PTFE screws) to hold the OMC vertically deforms the breadboard and cause the misalignment. Use something compliant or just release the screws.

The OMC was locked with Moku Pro.

Attachment 1: Electrical setup. The RF part of the REFL PD signal was fed into Moku pro, while the DC part was monitored on a scope.
Attachment 2: Servo setup. The modulation amplitude is 100mV.
Attachment 3: Image rejection LPF setup
Attachment 4: Laser PZT servo during lock acquisition
Attachment 5: Laser PZT servo for stational operation
Attachment 6: Laser Temp servo setting
Attachment 7: CCD Images during lock. The REFL is still limited by the mode mismatching component.
Attachments 8/9: The REFL locked / unlocked = 340mV/5.4V = 0.06 --> Mode Matching 94%
 

Horizontal beam centering along XARM

I tried to improve beam centering along XARM from the control room. First I realigned IMC until counts were recovered on MC TRANS QPD. The final IMC alignment state resulted in 960 cts transmission [Attachment 1].

Next I aligned the arms until transmission in both arms reached ~0.08 [Attachment 2]. In that state I recorded ETM/ITM beam spot positions below. Note that although the beam was miscentered by over 5mm on ETMX (horizontal), it was under 1mm on ITMX. Thus it seemed like a pointing issue. I then tried to lock MICH to record the beam spot on BS, but it never locked stably and the measurements were bogus.

Optic    LSCDoF     freq.(Hz)    ampl. (counts)    gpstime    Opt. gain (counts/nm)    Opt. gain_std    v (mm)    v_std      h (mm)    h_std

ETMY    YARM    211.11    500    1385168096    112.24    4.68           -1.25   0.47  -1.48   0.41
ITMY    YARM    211.11    500    1385168173    100.55    3.18            3.39   0.74   1.71   0.40
ETMX    XARM    211.11    500    1385168993    70.39     4.36           -2.92   0.60   8.39   1.56
ITMX    XARM    211.11    500    1385169082    79.36     3.17            2.90   0.60  -1.64   0.85

I proceeded to try to walk the beam a bit along XARM by moving TT2 in yaw and compensating with PR2. I moved both by ~40 steps and XARM transmission improved to just under 0.1 [Attachment 3].  However, the beam spot measurements looked pretty much the same; mode-matching into XARM was improved while pointing stayed constant. Next I locked PRY to measure the final beam spots on PRM/PR2/PR3.

Optic    LSCDoF     freq.(Hz)    ampl. (counts)    gpstime    Opt. gain (counts/nm)    Opt. gain_std    v (mm)    v_std      h (mm)      h_std

ETMY    YARM    211.11    500    1385234260    133.31    6.03            2.28   0.75   -0.74   0.43
ITMY    YARM    211.11    500    1385234343    121.44    3.14            3.91   0.52   -0.82   0.43
ETMX    XARM    211.11    500    1385234433    88.98     3.75           -0.76   0.41    6.16   1.18
ITMX    XARM    211.11    500    1385234546    103.35    4.50            3.60   0.67   -0.90   0.23
PRM     PRY    211.11    1000    1385236336    5.57      0.73           -8.13   16.67  -2.75   2.38
PR2     PRY    211.11    1000    1385236409    8.65      1.88            2.17   0.54   -7.71   3.39
PR3     PRY    211.11    1000    1385236483    6.39      1.74            4.83   1.50    9.17   6.25

With such high transmission in the arm cavities, alignment looked good and we decided it was OK proceed with aligning the LO/POP beams.

Lab temperature trend for 20 and 400 days:

- The lab temp significantly raised by 4 degC at Vertex and 6 degC at Xend. Yend saw no change.
  We have never seen such temp rise in the past 400days.

- The PSL temp went up at some point in the summer but we should check if this is real or any artifact.

[Paco, Vittoria, Murtaza, Radhika]

LO/POP alignment

We opened the ITMX and BS chambers for this work. First, both ITMs were misaligned to isolate the forward-propagating beam into the IFO. We saw that the transmitted beam through PR2 (LO) was clipping on the small POP mirror in front of LO1 [Attachment 1]. We decided to move that mirror out of the way and focus on aligning LO; then we would proceed to align POP.

Once the small mirror was moved, the LO beam looked fairly centered on LO1. At LO2, the beam was very misaligned in yaw, missing the optic [faint beam spot in Attachment 2]. I steered LO1 until the beamspot at LO2 was about centered [Attachment 3]. At this point, the beam was reflected off LO2 towards the ITMY table. 

I went back to check that the LO beam was not clipping anywhere on the ITMX table on its way to LO2 [Attachment 4].

Next I removed the spacer that was raising the height of the small mirror [Attachment 5]. ITMY was realigned so that we would recover the backwards-propagating reflection from the IFO. I placed the small mirror back to reflect the backwards-propagating beam transmitted through PR2 (POP) [far left beam in Attachment 6]. I verified that POP was hitting the next mirror and directed towards the in-air ITMX table [Attachment 7]. We closed up all chambers.

Next steps

Fine alignment of LO beam downstream of LO2 and and of POP out of the chamber will be done after PR2 is replaced.

Continued on the BHD Optics Prep:

The following mounts were prepared (they are not 100% tightened yet)
- OMC Refl Mirror Mounts: OMCiRj (i=1,2, j=1,2,3)
- HWP (fixed) -> a thread adapter is missing
- TFPs
- HWP Actuator

We'll extract LO3/LO4/AS2/AS3/BHDBS from the ITMY chamber.

Fixed HWP mount had very thin room at the center. I wasn't sure if I could mount the 1/2" HWP in it. Fortunately the HWP was quite thin (~1mm) and it just barely fit. (Attachments 2/3)

The fixed HWP mount had no 8-32 to 1/4-20 thread adapter.
I'm asking the C&B of the adapters. (Attachment 4)

- AS2 2" post is being C&Bed
- LO4 2.5" post is being C&Bed
- BHDBS spacer ring is coming back from C&B soon
- BHDBS 2.5" post is being C&Bed
- Faraday Rotater Base was ordered. Waiting for the delivery.
 

AS2/AS3/BHD BS/LO3/LO4 moved to BHD cleanroom

Attachment 1 shows the labeled optics on the ITMY table (from Koji). I recorded the initial e-bubble reading on the ITMY table: (x,y) = (0.03; 0.17). See Attachment 5 for orientation of the e-bubble (from chamber door: x-axis left to right; y-axis front to back).

I first cleared the extra steering mirrors (marked SM in Attachment 1). The e-bubble reading after clearing steering mirrors was: (x,y) = (0.03; 0.18). Note that fluctuations of 0.01 are common for the e-bubbles, so this is a negligible change. The steering mirrors were placed on the XEND flow bench [Attachment 2].

Next I removed the BHD optics, in the order of (LO4, LO3, BHD BS, AS3, AS2). This was arbitrary but made it easy to work front-to-back and remember reverse numeric order. These were placed on the BHD cleanroom table behind the OMC platform [Attachments 3, 4]. See attachments for labeled optics. 

The final e-bubble reading was: (x,y) = (0.00; 0.20). Similar (small) change in x and y directions. Final state of ITMY table in Attachment 5.

I started using this new code that Rana and I got from a random Git. It is for a Live Specgram. I was finally able to get it to pop up the plat atleast, but for some reason it is not platting the array from the C1:IOO-MC_F_DQ channel. The also does not seem to be in real-time yet. I will continue playing with this from home, but this is where I am now.

In-vac alignment / clipping

• [Done] SUSs aligned: TTs / PRM / PR2 / PR3 / BS / ITMs / ETMs / SR2 / LO1
• [Done] POP beam aligned
• To Do: LO2/AS4 alignment waiting for the BHD platform
• To Do: AS beam investigation: make sure the beam is not clipped with an IR viewer while AS1 is shaken
• [Done] PRM UL OSEM issue - missing PD signal (Resolved - [ELOG 18002])

BHD platform

• [Done] OMC external input/output optics
• [Done] OMC was locked
• BHD optics 85% prepared
• [Done] Optics came out from the chamber [ELOG 17996]
  • [Done] AS3/LO3 assembled [ELOG 18004]
  • AS2/LO4/BHDBS waiting for the posts
• To DoL C&B list
  • 2" x1 / 2.5" x2 OD1" posts
  • Thread adapter for HWP mount
  • Faraday Rotator Base (just arrived / in search)
  • #4-40 set screws to be C&Bed
  • Mighty Mouse connectors - coming out from the C&Bed  soon
• Picomotor ball bonding (EP30-2)
• DCPD installation
  • PD cans to be opened
• OMC electronics function tests (PZT/DCPD/QPD)
  • External electronic units are still in prep (KA)

PR2 suspension

• [Done] phi2"xt0.125" adapter ring -> A bag in the BHD clean room
• Start the assembly work once the alignment work is done. At the bake lab, probably?
• 40m lab clean booth is not vacant for more weeks

Other vent related maintenance

• To Do: Ribbon cable stays to be ordered.
• TP2 serial communication (Paco volunteers)
• Vacuum gauges (FRG calib etc) (JC to look into it)
  • Super Bee is the reference

Other maintenance

• Lab A/C issue (Warm @ Vertex and Yend) on going [ELOG Thread]
• Failed UPS (one at the control room, another at the 1X6 rack)
• Collect Flange bolts/nuts
• [Done] Put FB1 back [ELOG 18003]
• Megatron error beep (Rana)
• How to do with the drill press room.

I made modifications to the thermostats this morning in the lab:

X Arm

66°F ---> 68°F

Vertex

71°F ---> 69°F

Y Arm

69°F ---> 67°F

I will update tomorrow moring with a trend of the temperature changes. Rana mentioned it will take ~24 hrs for a notable change to happen.

The attached was the 2 days trend

Maybe I said X and Y moxed up in the meeting? The Yend A/C is the good one.

Yend temp was stable (0.5degC_pp) -> JC lowered the setting by 2 degF (=1.1degC) -> Yend temp went down by 1.5degC today. Makes sense.

Xend temp was high and unstable (2degC_pp) -> JC raised the setting by 2 degF (=1.1degC) -> Xend temp trend didn't change. Does not make sense.

Vertex temp was high and unstable (2degC_pp) -> JC lowered the setting by 2 degF (=1.1degC) -> Vertex temp trend didn't change. Does not make sense.

YEND thermostat was restored from 67 °F ---> 69 °F.

[Murtaza, Radhika]

PRM UL counts normal

We removed the extra DB25 cable (with cut wire isolating pin 5 [Attachment 1]), restoring the original PRM UL/UR/LL connections ---> UL counts ~650

Recap:

It may have been that the foil caps were causing pins 1 and 5 to short in the first place, so removing the caps and restoring the original cable fixed the issue. Final state in Attachment 2.

I saw FB1 was pushed into the rack (Attachment 1). Thank you very much for the work. But I did not see an elog about it.

Here is a good example of why timely elogs are so important.

• I saw that the seismometer signals were lost 3 hours ago, looking at the StripTool display on the control room wall. I wondered if there was a CDS crash or anything (but there wasn't).
• I went into the lab and found the FB was pushed in. I checked the rear side of the rack and found the ADC SCSI cable was half unplugged. (Attachment 2)
  Pushing the plug back into the connector made the PEM signals back into operation (Attachment 3)
• Even if I asked whether there was a problem with PEM, people would say, "We did nothing." But, this kind of unaware cause of another issue just by the presense of you in the lab is very common.
• If I could see an elog about the FB push written 3 hours ago, I could easily relate these two events, which were not so apparent to be associated.

Write your work of the day before you leave. You will not elog it tomorrow or even in the same evening at home.

• AS3/LO3 were assembled (Attachment 1)
• The BHD Platform extension plate was attached to the platform. This will be removed upon the installation into the chamber.

Remaining things to do:

• AS2 (DLC mount) / LO4 / BHD BS were fixed on the table but still waiting for the posts to come from C&B.

• Waiting for the C&B
  • 2" x1 / 2.5" x2 OD1" posts
  • Thread adapter for HWP mount
  • Faraday Rotator Base (just arrived / in search)
  • #4-40 set screws to be C&Bed
  • Mighty Mouse connectors - coming out from the C&Bed  soon
• Picomotor ball bonding (EP30-2)
• DCPD installation
  • PD cans to be opened
• OMC electronics function tests (PZT/DCPD/QPD)
  • External electronic units are still in prep (KA)

Tuning of the OMC locking

• Tried to measure the open-loop transfer function of the OMC lock -> failed due to some broken instrument.
• Added digital filter and spectrum tool on Moku Pro ("Multi Instrument" mode - Attachment 2)
• Locking with "Multi Instrument" mode
  • Only 2 input CHs / 2 output CHs are available -> combined laser temp out and the modulation out (Attachment 3)
  • This somehow made the PZT range limited to the half of the past. The lock became a bit tricky.
• Found that the oscillation is from 200kHz -> likely to be the PZT resonance
  • Implemented a low pass (Attachments 7/8)

The lock became less oscillative.
OMC REFL in-lock: 236mV
OMC REFL unlocked: 5.48
-> Mode-matching: 1-0.236/5.48 = 0.957

By the way, the above in-lock refl level was compared with the refl level with the cavity scan.
10Hz 800mVpp scan -> 524mV
  1Hz 800mVpp scan -> 324mV
Locked                       -> 239mV
I could be indicating the thermal effect?

A bunch of instruments are no longer functioning:

• SR560 brought from the workbench
  • CHA and the 600Ohm output have their BNCs loose.
  • Is this unit noisy? Connecting a cable on CHB made the lock stable??? (The unit was inserted in the loop)
  • "SR560 deficit" How many functioning SR560 do we have?
• 1201 Low noise amp (for alternative summing node)
  • The unit was brought from the cabinet -> simply broken
• SR785 brought from the workbench
  • With nothing connected to the BNCs
  • CHA: No matter what is connected, the spectrum did not change. This channel (CH1A/B) had been labeled "FLAKY".
  • CHB showed "H.V" and was fixed at 34dBV input range -> Is it internally connected to AC???
• DS345 shows the semi-constant voltage even though a sin wave was given.
• Phillips function generator simply did not run.