A correction on the previous elog about the REFL33Q noise:

The MC alignment servo wasn't great in the last 1 hour or so as it kept disturbing the MC lock. It was found to be due to some offsets in the MC trans QPD signals.

I put some values to cancel the offsets and then the lock became stable.

This is a first aid. So we need to take a closer look at the QPD signals and also probably the spot position on the QPD.

The symptom was that every time the alignment servo was engaged, at the beginning the amount of the transmitted light went to 27000 counts, which is good.

However, then the amount of the transmitted light slowly decreased in a time scale of ~ 20 sec or so, ending up with destruction of the MC lock.

According to the time scale I suspected that the servos using the trans QPD signals were doing something bad because their control width had been designed to be slow and slower than the rest of the servo loops.

I switched off the servos, called C1:IOO-TRANS_PIT and C1:IOO-TRANS_YAW and found the MC stayed locked stably with 27000 counts of the transmitted light.

Leaving the trans QPD servos off, I zeroed the offsets and then switched them on. It worked.

The values below are the current offset that I put.

                C1:IOO-MC2_TRANS_PIT_OFFSET = -0.115203
                C1:IOO-MC2_TRANS_YAW_OFFSET = -0.0323576
 

It seems that neither c1scx nor c1scy is working properly as their ADC counts are showing digital-zeros.

However the IOPs, c1gcx and c1gcy look running fine, and also the IOPs seem successfully recognizing the ADCs according to dmesg.

Also there is one more confusing fact : c1scx and c1scy are synchronizing to the timing signal somehow.

I restarted the c1scx front end model to see if this helps, but unfortunately it didn't work.

As this is not the top priority concern for now, I am leaving them as they are now with the watchgods off.

(I may try hardware rebooting them in this evening)

I tried to measure the beam profiles at the POP and POX ports as Koji mentioned in his entry (#6421).

However it turned out that the beam powers were too small to be measured with our beam scan at those ports.

So I will move on to measurements at the REFL port as Rana suggested because the laser power is much larger than that of POP and POX.

(If the data of the POP and POX beam profiles turn out to be very necessary, we will do the razor blade technique with a more sensitive photo diode)

[Suresh / Kiwamu]

Currently the REFL beam is bypassed by additional mirrors and blocked by a razor blade dump.

Therefore the signals associated with the REFL ports (e.g. REFL11, REFLDC and etc.) are unavailable.

Just be aware of it.

I have estimated how the mode profile of the PRM reflection should be, as shown in the plot blow.

A conclusion here is :

   we should be able to constrain the PRM curvature situation if measurements are precise and accurate enough with a level of less than ~ 100 um

In the calculation two cases are considered :

      (1) PRM has the correct curvature of  +122 m. This is shown as solid curves in the plot.

      (2) PRM has a wrong curvature of - 122 m (mirror is flipped) This is shown as dashed curves in the plot. 

Note:

 I have omitted the effect from the PRM thickness. Therefore PRM is dealt as just a curved reflector with RoC of +/- 122 m in the calculation.

[Suresh / Kiwamu]

 We did the 2nd round of the PRM reflection mode scan on Friday.

It seems that the PRM curvature maybe correct if we look at the vertical mode, however but the horizontal mode doesn't seem to agree with any of the expected lines.

In order to increase the reliability of the measurement, we need to confirm the beam profile of the incident beam by looking at the IP-POS beam.

Right now Suresh and Keiko are mode-scanning the IP-POS beam.

The plot below shows both the expected beam profiles (see the detail in #6444) and the actual data. 

(Discussion)

• Clipping at some optics. (Since the beam shape looked very Gaussian, the amount of the clipping could be very slight ?)
• Astigmatism at some optics. (Possibly in the telescope ?)

(Some distances)

(Some notes)

We did the following things prior to the measurement.

• Put a boost filter in the PRM_OLYAW to suppress the beam jitter below 1 Hz.
• Checked the MC WFS servo loop although it looked healthy.

For those who are interested in the actual data, I attache the actual data in zip file together with a python plot code.

The distance was set such that the 1st steering mirror (the one at the very left in the previous cartoon diagram #6445 ) in the REFL path is positioned at zero.

- - - Fitting results (chi-square fitting done by gnuplot):

All values are in unit of meter

# PRM (v) (Last tree points are excluded as the beam were clipped at the aperture of the beam scan)


w0          = 0.0015114        +/- 2.192e-05    (1.451%)
z0           = -4.46073         +/- 0.05605      (1.256%)

# PRM (h)

w0           = 0.00212796       +/- 1.287e-05    (0.6049%)
z0           = -2.53079         +/- 0.1688       (6.668%)

# ITM (v) (Last two points are excluded as the beam were clipped at the aperture of the beam scan)

w0           = 0.00190696       +/- 4.964e-05    (2.603%)
z0           = -8.09908         +/- 0.1525       (1.882%)

# ITM (h)

w0           = 0.0032539        +/- 4.602e-05    (1.414%)
z0           = -1.89484         +/- 1.524        (80.42%)

The dump and some temporary mirrors were removed and now the REFL beam is available again.

I locked PRMI with REFL signals, it locked as usual.

I was trying to make the DRMI lock more robust.

Increasing the gains of the oplev on SRM helped a lot, but the lock is still not solid enough for measurements.

According to some line injection tests, the SRCL and MICH signals show up in AS55Q with almost the same amplitudes.

I tried to diagonalize the input matrix (particularly MICH-SRCL in AS55) based on the result of the line injection tests, but I ran out the time.

Work continues.

I have measured the sensing matrix of the DRMI although the lock still doesn't stay for a long time.

As for the noise budget, it looks very tough as there are more glitches than that in the PRMI.

In this weekend I will take some more trials in the DRMI lock until I am satisfied.

[Jenne / Kiwamu]

 We have installed a broad band PD in the AS path in order to monitor the 110 MHz signal associated with the SRC.

The PD is currently connected to the POP110 demodulation board and it seems working fine.

I know this is confusing but right now the signal appears as "POP110" in the LSC front end model.

• Installed a 50% BS at the AS path
  
  • The AS beam is split to two path - one goes to AS55 and the other goes to the OSA.
  • The new BS is installed on the way of the OSA branch therefore AS55 isn't affected by the new BS.
• Installed a PDA10A
  
  • This is a silicon diode with a bandwidth of 150 MHz, and is fast enough to detect the 110 MHz signals.
  • The 110 MHz signal seems going up to approximately -40 dBm according to a coarse measurement with an RF spectrum analyzer.
  • Also a SMA-style high pass filter, HPF-100, was attached to the output to cut off unnecessary sidebands (e.g. 11, 22 MHz and etc.)
• Put a long BNC cable, which goes from the PD to LSC rack.
  • The end of the cable at the LSC rack was directly connected to the POP110 demod board.
  • The actual POP110 signal path is currently terminated by a 50 Ohm load and therefore this signal  is unavailable.
• Adjustment of the demodulation phase
  • The demod phase was adjusted to be 7 deg in the EPICS screen. This phase minimize the Q-signal.
  • Locking PRMI with sidebands resonating makes the AS110 signal ~ a few counts and this level is still noticeable.
  • Perhaps we may need to put an RF amplifier to get the signal bigger.

 I tried locking the DRMI to the signal-extraction condition with the new trigger by AS110.

A first thing I tried was : flipping the control sign of the SRCL while keeping the same control setups for the PRCL and MICH.

Occasionally the DRMI was "sort of" locked and hence I believe this setup must be a good starting point.

As a next step I will try some different gains and demodulation phase to make it more lockable.

(Time series)

• REFL33I => PRCL  G = -0.2
• AS55Q => MICH    G = -6
• AS55I => SRCL     G = 1   (G = -50 for the signal recycling condition)
• AS55 demod phase = 17 deg

It wasn't a dream or illusion -- I was locking the DRMI to the right condition last Wednesday (#6489).

Here is a snap shot of the AS-OSA signal taken today when the DRMI was locked with the same control settings (#6489).

The blue curve is data taken when the PRMI was locked for comparison.

You can see that both the upper and lower 55 MHz sideband are amplified by the SRC.

(Some notes)

Currently SRM is slightly misaligned such that the MICH optical gain at AS55Q doesn't increase so much with the presence of SRM.

With this condition I was able to acquire the lock more frequently than how it used to be on the Wednesday.

The next step is to gradually align SRM, to optimize the controls and to repeat this process several times until SRM is fully aligned.

Somehow I lost the good alignment, where the lock can be frequently acquired and hence I didn't go further ahead.

I will try locking the DRMI during the weekend again. My goal is to take time series when the DRMI is being locked and sensing matrix.

Here is a time series when the DRMI is being locked.

You can see that the AS110 goes up because the SRCL is engaged and amplifies the 55 MHz sidebands.

[Koji / Kiwamu]

 We have realigned the interferometer except the incident beam.

 The REFL beam is not coming out from the chamber and is likely hitting the holder of a mirror in the OMC chamber.

So we need to open the chamber again before trying to lock the recycled interferometers at some point.

--- What we did

•  Ran the MC decenter script to check the spot positions.
  • MC3 YAW gave a - 5mm offset with an error of about the same level.
  • We didn't believe in this dither measurement.
•  Checked the IP-POS and IP-ANG trends.
  • The trends looked stable over 10 days (with a 24 hours drift).
  • So we decided not to touch the MC suspensions.
• Tried aligning PRM
• Found that the beam on the REFL path was a fake beam
  • The position of this beam was not sensitive to the alignment of PRM or ITMs.
  • So certainly this is not the REFL beam.
  • The power of this unknown beam is about 7.8 mW
• Let the PRM reflection beam go through the Faraday
  • This was done by looking at the hole of the Faraday though a view port of the IOO chamber with an IR viewer.
• Aligned the rest of the interferometer (not including ETMs)
  • We used the aligned PRM as the alignment reference
  • Aligned ITMY such that the ITMY reflection overlaps with the PRM beam at the AS port.
  • Aligned the BS and SRM such that their associated beam overlap at the AS port
  • Aligned ITMX in the same way.
  • Note that the beam axis, defined by the BS, ITMX  and SRM, was not determined by this process. So we need to align it using the y-arm as a reference at some point.
  • After the alignment, the beam at the AS port still doesn't look clipped. Which is good.

---- things to be fixed

   - Align the steering mirrors in the faraday rejected beam path (requires vent)

   - SRM oplev (this is out of the QPD range)

   - ITMX oplev (out of the range too)

Awesome !

Wonderful ! I like the video -- the spatial mode looks pretty clean and much cleaner than what I observed in the old days.

Kiwamu and Steve have started venting the 40m vacuum envelope.

Preparation:

centered oplevs at resonating cavities,

ITM references were set by green pointer from the ends by Koji,

closed  PSL shutter and placed manual block into beam path,

checked  jamnuts in locked positions on bellows,

turned  HV off at PZT-Jena "steering mirror" power supply and OMC HV ps

checked  particle counts,

switched oplev servos off,

set up N2 cylinder to start vent from 1e-6 Torr to 25 Torr,

have ~ 6 cylinders of instrument grade compressed air to bring envelope from 25 Torr to 760 Torr

All three cranes were wiped off today.

 Kiwamu has completed the vent.

In this morning I found MC unlocked.

Steve restored the watchdogs before I found that.

Then I relocked MC and now MC is locked and working well.

The reflected DC power is ~0.38, which is usual number.

Now some pedestals, mirrors and lenses are left on the PSL table, since we are on the middle way to construct a PLL setup which employs two NPROs instead of use of PSL laser.

So Please Don't steal any of them.

Matt checked it in this morning and he found it's been locked during the night.

We are leaving the PLL as it is locked in order to see the long term stability. And we will check the results in early morning of tomorrow.

DO NOT disturb our PLL !!

(what we did)

After Mott left, Matt and I started to put feedback signals to the temperature control of NPRO.

During doing some trials Matt found that NPRO temperature control input has an input resistance of 10kOhm.

Then we put a flat filter ( just a voltage divider made by a resistor of ~300kOhm and the input impedance ) with a gain of 0.03 for the temperature control to inject a relatively small signal, and we could get the lock with the pzt feedback and it.

In addition, to obtain more stable lock we then also tried to put an integration filter which can have more gain below 0.5Hz.

After some iterations we finally made a right filter which is shown in the attached picture and succeeded in obtaining stable lock.

In this afternoon, Mott and I tried to find a beat note between two NPROs which are going to be set onto each end table for green locking.

At first time we could not find any beats. However Koji found that the current of innolight NPRO was set to half of the nominal.

Then we increased the current to the nominal of 2A, finally we succeeded in finding a beat note.

Now we are trying to lock the PLL.

P.S. we also succeeded in acquiring the lock

The HIGH and LOW channels are added into the burt request file "/target/c1losepics/autoBurt.req".

These values are used to colorize the alarm texts in the "C1DRIFT_MONITOR.adl" like a threshold. (the screenshot attached)

Hereafter these values will be automatically restored by the burt.  Happy !

We are going to set the waist size to 0.1 mm for the beam going through the triple resonant EOM on a new PSL setup.

When we were drawing a new PSL diagram, we just needed to know the waist size at the EOM in order to think about mode matching.

This figure shows the relation between the waist size and the spot size at the aperture of the EOM.

The x-axis is the waist size, the y-axis is the spot size. It is clear that there is a big clearance at 0.1 mm waist size. This is good.

Also it is good because the waist size is much above the damage threshold of the EO crystal (assuming 1W input).

The attached file is the python code for making this plot.

We have installed the new Video Matrix.

Its still in an intermediate state, so don't try to "fix" anything before Kiwamu and I get back onto it in the afternoon.

The status so far is that we have removed the old switch (it was a 256 input x 128 output !! mux)  and installed the new one in the same rack. We have hooked it up to the CDS network and have set up its matrix by using the web interface (i.e. NOT EPICS).

Along the way, we discovered that there is lack of impedance matching in the video all over the 40m. Video signals are RF and need to be treated that way. The PSL signals are T'd around and sent on 50 Ohm cables to high impedance monitor inputs.

We should eliminate any switches besides the new one (called Luciana) and control the PSL's Video Monitor from the main MUX interface. No more Rogue Video Switches.

Another couple of things we have found is about RCR camera.

(1) The long cable which connects the RCR camera box and the video matrix doesn't work. Although the signal is alive and we can see it by the local tv monitor nearby PSL.

(1) The reflected beam going to the camera is too weak to see in the monitor.  We found a strange polarized cube splitter in front of the camera. We should modify it sooner or later.

 This morning I and Steve replaced  the dry fore pump of TP3, which is located under the y-arm.

After replacing it we confirmed vacuum normal condition. The fore line pressure of TP3 went down to 11 mTorr from 750 mTorr

  Attached picture is new pump after setup.

Kiwamu and Steve, from yesterday

PRM and BS oplev paths were relaid after setting 1/2 OSEM voltages. The incident beam on suspended optics are centered  within  ~ +- 2 mm

I noticed many unvected ss screws are used on the big Al table tops. The SS 1/4-20 screws

 used on the optical tables in vacuum MUST be VENTED!

Also, please use  SS clamps. Replace aluminum ones when you can. We have plenty baked ones.

Some of the suspensions got watchdog tripped -> enabled -> damped.

The MC mirrors got slightly misaligned.

How much is the width?

We removed the Lightwave MOPA Controller from 1X1 (south)  It was a real painfully messy job to pull out the umbilical.

Note: the umbilical is shading it plastic cover. It is functional but it has to be taken out side and cleaned. Do not remove it from it's plastic bag in a clean environment.

Now Joe has room for IOO chassy  in this rack.

We also removed the Minco temp controller and ref. cavity ion pump power supply.

We removed the Lightwave MOPA Controller, PA#102, NPRO206 power supply to make room for the IOO chassy at 1X1 (south) rack.

The umbilical cord was a real pain to take out. It is shading its plastic cover. The unused Minco was disconnected and removed.

The ref. cavity ion pump controller- power supply was temporarily taken out also.

We found that a transistor was broken from yesterday spark too. We partially fixed TTFSS, and it should be enough for  testing purpose.

From yesterday test, we found that the RF amplifier for LO signal was broken. There was no spare at the electronic shop at Downs,

so we shorted the circuit for now.  Another part which was broken too was a transistor, Q3 PZT2222A, on D0901846.

It was removed and two connections, which are for Q3's 1 and 3 legs, are shorted. Now the voltages out from the regulators are back to normal.

We are checking a MAX333A switch, U6A on D0901894. it seems that the voltage that controls the switch disappears.

There might be a bad connection somewhere. This will be investigated next.

  Q3, a PZT2222A transistor, on D0901846 is replaced by a GE-82. However, the board is still not fully function.

Since Q3, PZT2222A, was broken, I went to Wilson house and got some SP3904's for replacement. But somehow, I broke it during

installation, and did not notice it, and resumed the test. When I got to test 8 on the list, the TTFSS did not work as specified.

Koji checked and found out that -15V, Nref, Vref voltages output did not work correctly. So the SP3904 I installed was removed

and replaced with another SP3904 by Koji, and Vref is working. 

Q4 transistor is broken as well and it was replaced by GE 82.

Q1 might be broken too since -15V out is not working.

I'll go to Wilson house to get more transistors next week.

After the broken parts have been replaced, I have to make sure that I separate the power supply board from the rest of the circuit and

check if all V outputs are  working, then reconnect the board and check if the current input is reasonable before resume the test.

I hope the wrong input voltage problem today wouldn't damage anything else.

We found a small PCB defect which is an excess copper shorting circuit on the daughter board,

it was removed and the signal on mixer monitor path is working properly.

 We were checking the new TTFSS upto test 10a on the instruction, E1000405 -V1. There was no signal at MIXER mon channel.

It turned out that U3 OpAmp on the daughter board, D040424, was not working because the circuit path for leg 15 was shorted

because of the board's defect. We can see from fig1 that the contact for the OpAmp's leg (2nd from left) touches ground.

We used a knife to scrap it out, see fig 2, and now this part is working properly.

We replaced GE81 by PZT2907A (PNP transistor) in TTFSS #7, it's working fine.

  Last time I broke Q4 transistor, which is used in the low noise power module for TTFSS, (see the schematic) and could not find another PZT2907A, so GE81 was used temporarily. Now we changed it back to PZT2907A as designed.  I tested it by checking the voltage outputs of the board. It works fine, all voltage outputs are correct. I labeled one of the slot on the blue cabinet tower and kept the rest of the transistors there.

I tested the new table top frequency stabilization system(TTFSS),
I haven’t finished it yet, and accidentally fried one amplifier in the circuit.

We received three sets of a new TTFSS system which will replace the current FSS.
It needs to be checked that the system works as specified before we can use it.

- Result

I followed the instruction written on E10000405-v1
The first test inspected how much the currents were drawn from the +/- 24 V power supply.
+24 V drew 350 mA and -24 V drew 160 mA as shown on pwr supply’s current monitor.
They exceeded the specified value which was 200 +/- 20 mA, but nothing went wrong during the test.
Nothing got overheated, all voltage outputs were correct so I proceeded.
I have gone down the list to 6, and everything works as specified.

- Correcting the document for the test procedure

I found a few errors on the instruction document. I’ll notify the author tomorrow.

- How GVA-81 amplifier on D0901894 rev A got fried

During the test, I used a mirror on a stick that looked like a dental tool to see under the board.
Unfortunately, the steel edge touched a board and caused a spark. The voltage on -24 dropped to -16.
I think this happened because the pwr supply tried to decrease the current from shorted circuit,
as I shorted it only short time ( a blink of an eye), it could not reduce the voltage to zero.
When I was checking the power supply and about to adjust the voltage back to the right value
(about 4-5 seconds after the spark,) smoke came out of the circuit.

Koji investigated the circuit and found that a GVA 81 amplifier was broken.

This was checked by applying 5V to the amp, and slightly increasing the current.
The voltage dropped to zero as the amp was broken, so its circuit was shorted.

I’ll see if I can replace this at EE lab at Downs.
If I cannot find a spare one, I’ll replace it with a resistor and resume the test procedure.
Because it amplifies LO signal, which won’t be used during the test.

 I propose we work around this problem with giant flip-flops.  These are in the vein of the take-off-your-shoes-and-put-on-Crocs, without the taking off your shoes part.  They're a little annoying on the sticky mats, but otherwise great.  They are also super easy to put on and take off without hands, so there's no excuse for wearing them around the control room. 

I propose we buy many pairs of the smalls in green (since we already have one green small...they are big on me, so should be just right for most people), and a few mediums in, say, blue, and a few larges in black, and then maybe a few extra larges in green for people with extraordinarily large feet (they only have 3 colors).  Then we can keep a few pairs of each by each door to the lab, and have no more tracking dirty control room filth into the lab.

The UL signal of the shadow sensor on ETMY went to zero this evening.

This was due to a loose connection on the cross connection board on the 1Y4 rack.

In order to make them tighten, a combination of stand-offs and screws were installed on the connectors. They won't be loose any more.

 Yuta has removed my ethernet connection. Help me!!!

rossa:mDV>ping mafalda
PING mafalda.martian (192.168.113.23) 56(84) bytes of data.
From rossa.martian (192.168.113.215) icmp_seq=2 Destination Host Unreachable
From rossa.martian (192.168.113.215) icmp_seq=3 Destination Host Unreachable
From rossa.martian (192.168.113.215) icmp_seq=4 Destination Host Unreachable

--- mafalda.martian ping statistics ---
5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3999ms
, pipe 3

The calibration is applied by adding an extra gain. But, I missed the point that I should be doing this outside the phase-tracking loop....my BAD .

So I modified the model such that the calibration is done without disturbing the phase tracking loop.

Right now, epics input 'PHASE_OUT_CALIB' accepts the calibration and we get the calibrated phase tracker output converted from deg to Hz at 'PHASE_OUT_HZ'.  I have also made it a DAQ channel to be used with dataviewer and dtt.

medm screens have been modified to accommodate these additions to the phase tracker screen. I used Yuta's phase tracker calibration data in elog to set PHASE_OUT_CALIB in the medm screens.

Measured frequency noise is ~10Hz/rtHz @100Hz. 

Measure the out-of-loop noise of Xarm ALS:

1. The X-arm was locked for IR using PDH error signal.

2. 'CLEAR HISTORY' of the phase tracker filters.

3. Measured the power spectrum of the phase tracker output. I have used the newly created calibrated channel "PHASE_OUT_DQ. So the phase tracker output now reads in Hz.

Discussion:

The measurement was done with beat note frequency at ~40MHz. The flat noise level of 10Hz/rtHz from 20-100Hz (in plot 2) is not good. We should investigate as to what sets this noise level. The spike at 60Hz is because the 60Hz frequency comb filter was not enabled.

I plan to the following to get a clearer outlook
1. Connecting the beat box to an RF source and measure the noise levels for a range of frequency inputs to the beatbox.
2. Measure the noise at C1:ALS-BEATX_FINE_I_IN1 (before the antiwhitening filters) and check whether the new whitening filters has done anything good with respect to minimizing the DAQ noise.

X arm stabilized using ALS while PRMI stayed locked

[Rana, Lisa, Jenne, Manasa]

Attachment 1

Time series : ALS enabled at t = 0 and disabled at t = 95s

What we did:
1. Jenne will elog about ASC (POP QPD) updates.
2. Found the beat note between Xarm green and PSL green.
3. Stabilized arm fluctuation by enabling ALS servo.
4. Scanned the arm for carrier resonance by ramping on the offset and set the offset such that we had IR resonating (TRX fluctuated between 0.1 and 0.8 counts).
5. Disabled the ALS servo and locked PRMI using AS55 for MICH and REFL33 for PRCL.
6. Enabled ALS.

Discussion:
Enabling ALS to detune the arm out of resonance kept PRMI locked  (currently for a span of few tens of seconds). However we could not see PRMI locked as stably compared to when the arms are misaligned. Everytime the offset was set IR to resonate, the PRMI was kicked out of lock.

Also there is some leakage at the arm transmission when PRMI was locked. The leakage was visible at ETMX transmission as flashes in different higher order modes indicating the not-so sufficient ALS stability. The leakage sets an offset at TRX measuring 0.01-0.05 counts.

To do list:
The ALS_OFFSETTER1 has to be calibrated in FSR. We were giving random offsets to do the offset scan.

Misc:
Installed a filter before ETMXT camera to remove the refl green. (Note to myself: The filter needs to go on a better mount/adapter).

I found WFS had been left disabled from sometime yesterday. I don't see anyone mentioning  when and why they had turned OFF the WFS servo.

I aligned MC and turned ON the WFS servo. MC is back.

[Koji, Manasa]

I wanted to investigate on the ALS electronics(in particular the beatbox and the phase tracker) and find out if the beatbox is showing a linear behavior
as we expect it to and as to why we have been seeing sudden jumps at the phase tracker output.

I have been using the Xarm part of the beabox.
I used Marconi as well as signal generator to do frequency sweep/modulation at the RF input of the beatbox and looked at the I_MON output of the beatbox.

We observed sudden jumps in the beatbox output from time to time while we either varied the carrier frequency or the RF amplitude.
Also the beatbox output shows high frequency oscillations at ~95MHz (source unknown). It is for sure that the beatbox is not behaving the way it should
but we could not tell more or troubleshoot with the beatbox mounted on the rack.

I am going to let Annalisa do her Y arm ALS scan tonight and pull out the beatbox tomorrow to fix it.

 The beatbox output showed high frequency oscillations during the troubleshooting process yesterday. I removed the beatbox from the rack. With no RF inputs, just powering the beatbox showed these high frequency oscillations at the beatbox output. This confirms that these oscillations are from the op-amp AD829JR. I replaced these with low noise OP27G. Also I removed the AD829JR that were soldered to the frequency divider and comparator which are not being used. Output buffer U10 was also removed.

After replacing with OP27G, I rechecked the beatbox with and without the RF input. There were no more high frequency contaminations and beatbox seemed to behave as it is supposed to when a frequency modulated RF input is fed. I put the beatbox back on the rack and did  a quick recheck.

Before (top) and after (bottom) pictures

I found the beat note for X arm. I did not change anything this morning (to the best of my knowledge). Hooking up the spectrum analyzer, I could find the beatnote signal at the PD RF output, after the amplifier and also at the MON port of the beatbox. I still don't know what changed from the last night set of trials