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ID Date Author Type Category Subjectup
  2789   Mon Apr 12 16:20:05 2010 AlbertoConfiguration40m UpgradingREFL55 improved
During the commissioning of the AS55 PD, I learned how to get a much better rejection of the 11MHz modulation.
So I went back to REFL55 and I modified it using the same strategy. (Basically I added another notch to the circuit).
After a few days of continuous back and forth between modeling, measuring, soldering, tuning I got a much better transfer function.

All the details and data will be included in the wiki page (and so also the results for AS55). Here I just show the comparison of the transfer functions that I measured and that I modeled.

I applied an approximate calibration to the data so that all the measurements would refer to the transfer function of Vout / PD Photocurrent. Here's how they look like. (also the calibration will be explained in the wiki)

2010-04-12_REFL55_TF_model_to_meas_comparison.png.

The ratio between the amplitude of the 55Mhz modulation over the 11MHz is ~ 90dB

The electronics TF doesn't provide a faithful reproduction of the optical response.

  4622   Wed May 4 12:07:48 2011 SureshUpdateRF SystemREFL55 installed on the AP table

REFL55 has been installed on the AP table.  REFL11 has been moved to make space for a 50% beam splitter. The reflected beam from this splitter is about 30% of the transmitted beam power.  The reflected beam goes to REFL11 in the current configuration.  The DC levels are 1.2V on REFL 11 and 3.5V on the REFL55.

I redid some of the cabling on the table because the we need to choose the heliax cables such that they end up close to the demod board location.  As per the 1Y2 (LSC) rack layout given here, some of the PD signals have to arrive at the top and others at the bottom of the LSC rack.

Currently the PDs are connected as follows:

 

REFL11 PD --> Heliax (ASDD133) (arriving at the top of LSC rack) --> REFL11 Demod Board 

REFL55 PD --> Heliax (REFL166) (arriving at the top of LSC rack) --> AS55 Demod Board

AS55 PD --> Heliax (AS166) (arriving at the top of the LSC rack) --> not connected.

 

We are waiting for the Minicircuits parts to modify the rest of the demod boards.

 

The heliax cables arriving at the LSC rack are not yet fixed properly.  I hope to get this done with Steve's help today.

 

 

  11208   Wed Apr 8 13:26:47 2015 ericqUpdateLSCREFL55 signal back to its normal ADC inputs

As the POP55 demod board is actually demodulating the REFL55 signal, I have connected its outputs to the REFL55 ADC inputs. Now, we can go back to using the REFL55 input matrix elements, and the data will be recorded. 

I have changed the relevant lines in the locking script to reflect this change. 

  13280   Thu Aug 31 00:52:52 2017 gautamUpdateLSCREFL55 whitening board debugging

[rana,gautam]

We did an ingenious checkup of the whitening board tonight.

  • The board is D990694
  • We made use of a tip-tilt DAC channel for this test (specifically TT1 UL, which is channel 1 on the AI board). We disconnected the cable going from the AI board to the TT coil driver board.
    • as opposed to using a function generator to drive the whitening filter, this approach allows us to not have to worry the changing offsets as we switch the whitening gain.
    • By using the CDS system to generate the signal and also demodulate it, we also don't have to worry about the drive and demod frequencies falling out of sync with each other.
  • The test was done by injecting a low frequency (75.13 Hz, amplitude=0.1) excitation to this DAC channel, and using the LSC sensing matrix infrastructure to demodulate REFL55 I and Q at this frequency. Demod phases in these servos were adjusted such that the Q phase demodulated signal was minimized.
  • An excitation was injected using awggui into TT1 UL exc channel.
  • We then stepped the whitening gains for REFL55_I and REFL55_Q in 3dB steps, waiting 5 seconds for each step. Syntax is z step -s 5 C1:LSC-REFL55_I_WhiteGain +1.0,15 C1:LSC-REFL55_Q_WhiteGain +1.0,15
  • Attachment #1 suggests that the whitening filter board is working as expected (each step is indeed 3dB and all steps are equal to the eye).
  • Data + script used to generate this plot is in Attachment #2.

I've restored all connections at that we messed with at the LSC rack to their original positions.

The TT alignment seems to be drifting around more than usual after we disconnected one of the channels - when I came in today afternoon, the spot on the AS camera had drifted by ~1 spot diameter so I had to manually re-align TT1. 

Quote:
 

Based on my tests, everything on the Demod board seems to work as expected. I need to think more about what else could be happening here - specifically do a more direct test on the whitening board.

Attachment 1: REFL55_whtCheck.pdf
REFL55_whtCheck.pdf
Attachment 2: REFL55_whtChk.tar.gz
  15977   Mon Mar 29 19:32:46 2021 gautamUpdateLSCREFL55 whitening checkout

I repeated the usual whitening board characterization test of:

  • driving a signal (using awggui) into the two inputs of the whitening board using a spare DAC channel available in 1Y2
  • demodulating the response using the LSC sensing matrix infrastructure
  • Stepping the whitening gain, incrementing it in 3dB steps, and checking if the demodulated lock-in outputs increase in the expected 3dB steps.

Attachment #1 suggests that the steps are equal (3dB) in size, but note that the "Q" channel shows only ~half the response of the I channel. The drive is derived from a channel of an unused AI+dewhite board in 1Y2, split with a BNC Tee, and fed to the two inputs on the whitening filter. The impedance is expected to be the same on each channel, and so each channel should see the same signal, but I see a large asymmetry. All of this checked out a couple of weeks ago (since we saw ellipses and not circles) so not sure what changed in the meantime, or if this is symptomatic of some deeper problem.

Usually, doing this and then restoring the cabling returns the signal levels of REFL55 to nominal levels. Today it did not - at the nominal whitening gain setting of +18dB flat gain, when the PRMI is fringing, the REFL55 inputs are frequently reporting ADC overflows. Needless to say, all my attempts today evening to transition the length control of the vertex from REFL165 to REFL55 failed.

I suppose we could try shifting the channels to (physical) Ch5 and Ch6 which were formerly used to digitize the ALS DFD outputs and are currently unused (from Ch3, Ch4) on this whitening filter and see if that improves the situation, but this will require a recompile of the RTCDS model and consequent CDS bootfest, which I'm not willing to undertake today. If anyone decides to do this test, let's also take the opportunity to debug the BIO switching for the delay line.

Attachment 1: REFL55wht.png
REFL55wht.png
  14961   Wed Oct 9 22:02:58 2019 gautamUpdateLSCREFL55 whitening issue

This problem has re-surfaced. Is this indicative of some problem with the on-board VGA? Even with 0dB of whitening gain, I see PDH horns that are 10,000 ADC counts in amplitude, whereas the nominal whitening gain for this channel is +18dB. I'll look at it in the daytime, not planning to use REFL55 for any locking tonight.

  333   Fri Feb 22 11:11:00 2008 robUpdateElectronicsREFLDD problem found

I used a network analyzer that actually works to find a problem in the REFLDD electronics chain. There was loose (=bad) SMA-BNC adaptor on the output of channel one of the HP RF Amplifier. It worked intermittently, so going onto the ISCT and fiddling with cables could sometimes temporarily fix the problem. The bad adaptor has been given to Andrey to discard.
  1469   Fri Apr 10 04:54:24 2009 YoichiUpdateLockingREFL_DC for CARM
Suggested by Rob and Rana's simulation works, I tried to use REFL_DC for the CARM error signal.

My current guess for the cause of the 3.8kHz peak is the following.
The AF sidebands created by the laser frequency drive are reflected by the IFO to the symmetric port if the arms are perfectly symmetric.
However, if there is asymmetry in the arm cavities (such as loss imbalance, ITM transmission difference etc) the sidebands are scattered from the common mode to the differential mode. If our CARM error signal has a large response also to the differential mode (i.e. DARM), the loop is closed. At the DARM RSE frequency, the AF sideband in the differential mode is enhanced and creates a peak in the CARM response.
What Rob's plots show is that PO_DC has a larger response to DARM than REFL_DC has. You can see this from the curves of CARM offset = 0 (black ones).
When the CARM offset is zero, the CARM signal should go to zero. Therefore, the black curves show the residual DARM response. In the case of PO_DC, the black curve is very large suggesting a large DARM coupling.

Now I changed the cabling at the LSC rack to put REFL_DC into the REFL2 input of the CM board.
The REFL_DC signal is put through a 160kHz RC LPF and split to the ADC and the CM board (AC coupled by a large capacitor).
I modified the cm_step script to use PD4_DC as CARM error signal. (The old script is saved as cm_step.podc).
Since the polarity of the REFL_DC signal is opposite to the PO_DC, I flipped the polarity switch of the CM board.
This will flip the sign of the RF CARM signal because this switch flips the polarity of the both inputs.
We have to flip the sign of the RF CARM signal with the SR560 sitting on the LSC rack, which I haven't done yet.

With some tweaks of the gains and addition of two lag-lead filters to PD4_DC, I was able to completely hand off the CARM error signal to REFL_DC.
The attached plot shows the AO path loop gain at arm power = 7. The 3.8kHz is gone, although there is some phase ripple around 3.8kHz.

Since the gain behavior of the REFL_DC is different from the PO_DC, I'm now working on the power up part of the script, adjusting the gains as the power goes up.
Attachment 1: AO-loop-gain-CARM-REFL_DC.png
AO-loop-gain-CARM-REFL_DC.png
  9932   Thu May 8 17:00:56 2014 rana, QSummaryLSCREFL_DC handoff didn't work last night

Last night after checking cabling and turning on ISS, we tried several times to handoff to REFL_DC but it didn't work at all.

Some issues:

  1. The ISS was injecting a lot of very low frequency power fluctuations because of bad AC coupling.
  2. The SR560 @ LSC rack was saturating a lot with the x10 gain that Jenne and Rana put in; we turned it back to G = 1.
  3. The ISS was also saturating a lot. We turned it off around 4 AM, but still no success.
  4. The ALS sequence for finding the Red Resonance takes too long (~2 minutes), so we're trying a faster scheme tonight.
  9936   Fri May 9 04:51:13 2014 ericqSummaryLSCREFL_DC handoff didn't work last night

Quote:

Last night after checking cabling and turning on ISS, we tried several times to handoff to REFL_DC but it didn't work at all.

Some issues:

  1. The ISS was injecting a lot of very low frequency power fluctuations because of bad AC coupling.
  2. The SR560 @ LSC rack was saturating a lot with the x10 gain that Jenne and Rana put in; we turned it back to G = 1.
  3. The ISS was also saturating a lot. We turned it off around 4 AM, but still no success.
  4. The ALS sequence for finding the Red Resonance takes too long (~2 minutes), so we're trying a faster scheme tonight.

 Still no success tonight

  • We took CARM OLTFs at various CARM offsets and could clearly see the peak in the optical TF (in once case ~2.5kHz), which gave us an indication of our offset (~200pm)
  • REFLDC effectively sees the same plant TF as the transmission signals plus a zero at ~110 Hz, at all offsets under 1nm, from my simulations; this pushes up the optical resonance and causes a loop instability when we try to handoff. 
  • We need to make the CARM OLTF steeper to suppress this instability, but also to make a good crossover with the AO path, which otherwise has too similar of a slope around the UGF, as we saw with our one arm test. 
  • We're thinking of trying to turn the AO path on with REFLDC while keeping the arms on SQRTINV signals. This may be tricky, but if we can get the loop bandwidth above the optical peak, it'll be a lot easier to deal with, and transfer digital control to REFLDC as well. 
  3223   Wed Jul 14 19:15:26 2010 GopalSummaryOptic StacksREVISION: Eigenfrequency Analysis of Single Stack Complete

My previous eigenfrequency analysis was incorrect by two orders of magnitude due to the misuse of Young's Modulus information for Viton. After editing this parameter (as documented on 7/14 19:00), the eigenmodes became much more reasonable. I also discovered the Deformation option under the Surface Plotting Options, which makes the eigenmodes of the single stack much more apparant.

Attached are pictures of the first four eigenmodes:

First Eigenmode: y-translational, 7.49 Hz

Eigenfrequency_1_Stack4.png

Second Eigenmode: x-translational, 7.55 Hz

Eigenfrequency_2_Stack4.png

Third Eigenmode: z-rotational, 8.63 Hz

Eigenfrequency_3_Stack4.png

Fourth Eigenmode: z-translational, 18.26 Hz

Eigenfrequency_4_Stack4.png

 

Attachment 2: Eigenfrequency_2_Stack4.png
Eigenfrequency_2_Stack4.png
  165   Wed Dec 5 13:49:08 2007 albertoUpdateElectronicsRF AM PD lines monitor
In the last weeks Iíve been working on the design of an electronic board to measure directly the power of the main spectral lines on of the RF-AM photodiode from as many independent outputs. The idea is to have eventually a monitor channel in the CDS network for the power of each line.
Looking at at the spectrum from the RF-AM PD (see attached plot), there are 5 main lines:
Frequency
3 fsr = 33 195 439 Hz
4 fsr = 66 390 878 Hz
12 fsr = 132 781 756 Hz
15 fsr = 165 977 195 Hz
18 fsr = 199 172 634 Hz

Two main approaches have been proposed for the circuit depending on the way followed to isolate the lines:
1) Filters: the frequencies are separated by narrow notch filters, then a diode bridge rectifies and a low pass filter extracts the DC component.
2) Mixers: for each frequency there is a mixer driven by a copy of the correspondent modulation frequency provided by the function generators (the Marconi). The mixers automatically give the DC component of the rectified signals.
Because of the phase lags that we should compensate if we used mixers, we would prefer the first approach, if it works.
Starting with a tolerance of about 10% between the channels, the spectrum (see attachment) sets the constraint to the filterís suppression:
Filter central frequency [MHz]******Suppression within 30 Mhz [dB]
33*********************************-7-20 = -27
66**********************************7-20 = -13
133*********************************12-20 = -8
166********************************-12-20 = -32
199*********************************10-20 = 10

So far Iíve tried two kinds of designs for the filters, Butterworth (see attachment) and LC and I'm measuring transfer functions tuning the components to match the central frequency and the bandwdth of the filters with the requirements.

The frequencies weíre dealing with are rather high and several adjustments had to be done to the measurement system in order to shield the circuit from the impedance of the input and the output line (i.e., amplifier turned out to be necessary). Also, an the mixer had to be replaced to an RF one.
It seems I'm now measuring new transfer functions (which look quite different from what I've got with no amplifiers).
To be posted soon.
Attachment 1: alberto.spectrum2.png
alberto.spectrum2.png
Attachment 2: Butterworth.PNG
Butterworth.PNG
  2350   Thu Dec 3 15:55:24 2009 AlbertoAoGLSCRF AM Stabilizer Output Power

Today I measured the max output power at the EOM output of one of the RF AM Stabilizers that we use to control the modulation depth. I needed to know that number for the designing of the new RF system.

When the EPICS slider of the 166 MHz modulation depth is at 0 the modulation depth is max (the slider's values are reversed : 0 is max, 5 is min; it is also 0 for any value above 5, sepite it range from 0 to 10).

I measured 9.5V from the EOM output, that is 32 dBm on a 50 Ohm impedance.

  12771   Mon Jan 30 19:07:48 2017 gautamUpdateIMCRF AM stabilization box pulled out

[johannes, gautam]

We pulled out the RF AM stabilization box from the 1X2 rack. PSL shutter was closed, marconi output, RF distribution box and RF AM stabilization box were turned off in that order. We had to remove the 4 rack nut screws on the RF distribution box because of the stiff cables which prevented the RF AM stabilization box extraction. I've left the marconi output and the RF distribution boxes off, and have terminated all open SMA connections with 50 ohm terminators just in case. Rack nuts for RF distribution box have been removed, it is currently sitting on a metal plate that is itself screwed onto the rack. I deemed this a stable enough ledge for the box to sit on in the short run, while we debug the RF AM stabilization box. We will work on the debugging and re-install the box as soon as we are done...

  12772   Tue Jan 31 01:07:20 2017 LydiaUpdateIMCRF AM stabilization box pulled out

[gautam, Lydia]

We looked at the RF AM stabilizer box to see if we could find out 1) Why the output power is so low, and 2) Why it can't be changed with the DC input "MOD CONT IN." Details to follow, attached is the annotated schematic from DCC document D000037

We are not returning the box tonight so the PSL shutter remains closed. 

Attachment 1: AM_stablilizer_annotation.pdf
AM_stablilizer_annotation.pdf
  12773   Tue Jan 31 13:46:34 2017 ranaUpdateIMCRF AM stabilization box pulled out
  1. What is the probe situation? Ought to use a high impedance FET probe to measure this or else the scope would load the circuit.
  2. The ERA amplifiers are known to slowly die over ~10 year times scales. Search our ELOG for ERA-5. We'll have to replace some; ask Steve to order if we don't have many in the Plateau Tournant.
  3. What kind of HELA are the HELA amplifiers? Please a link to the data sheet if you can find it. I wonder what the gain and NF are at 30 MHz. I think the HELA-10D should be a good variant.
  12775   Tue Jan 31 14:17:48 2017 gautamUpdateIMCRF AM stabilization box pulled out

> What is the probe situation? Ought to use a high impedance FET probe to measure this or else the scope would load the circuit.

We did indeed use the active probe, with the 100:1 attenuator in place. The values Lydia has quoted have 40dB added to account for this.

> What kind of HELA are the HELA amplifiers? Please a link to the data sheet if you can find it. I wonder what the gain and NF are at 30 MHz. I think the HELA-10D should be a good variant

The HELA is marked as HELA-10. It doesn't have the '+' suffix but according to the datasheet, it seems like it is just not RoHS compliant. It isn't indicated which of the varieties (A-D) is used either on the schematic or the IC, only B and D are 50ohms. For all of them, the typical gain is 11-12dB, and NF of 3.5dB.

  12782   Tue Jan 31 22:28:39 2017 LydiaUpdateIMCRF AM stabilization box pulled out

[rana, gautam, lydia]

Today we looked at the schematics for the RF AM stabilizer box and decided that there were an unnecessary amount of attenuators and amplifiers cancelling each other out and adding noise. At the end of the path are 2 HELA-10D amplifiers which we guessed based on the plots for the B version would have an acceptable amount of compression if the output of the second one is ~27dBm. This means the input to the first one should be a few dBm. This should be achieved with as simple a path as possible.

This begged the question, do we need the amplitude to be stabilized at all? Maybe it's good enough already when it comes into this box from the RF distribution box. So I tried to measure the AM noise of the 29.5 MHz signal that usually goes into the AM stabilizer:

  • I first measured the power to be 12.8 dBm with the AG4395.
  • I sent the signal through a splitter, then sent one side attenuated by 3 dB to the LO side of a level 7 mixer, and the other side attenuated by 10 dB to the RF side of the mixer.
  • The output of the mixer went through a lowpass filter at 1.9 MHz (with a 50Ω inline terminator). Initially I connected this directly to a DAQ channel (C1:ALS-FC_X_F_IN), but the ADC noise was stronger than the AM signal.
  • To fix this I used the SR560, AC coupled with a gain of 10^4. Attachment 1 is a spectrum of the noise measured with everything connected as described, and also for separate portions of the signal chain:
    • I measured the ADC noise by connecting a terminator to the cable going to DAQ.
    • I measured the mixer noise by putting a terminator on the RF input (and the end of the cable that was connected to it), while still driving LO.
    • I measured the SR560 noise by putting a terminator on the input.

It seems like I'm getting mostly noise from the SR560. Maybe it would be better to use an SR785 to take data instead of DAQ, and then skip the SR560? At low frequencies it seems like the AM noise measurement may be actually meaningful. In any case, if the actual AM noise from the crystal is lower than any of these other noise sources, it means we probably don't need to stabilize the amplitude with a servo, which means we can simplify the AM stabilizer board considerably to just amplify what it gets to 27 dBm.

Attachment 1: AM_noise.pdf
AM_noise.pdf
  12783   Wed Feb 1 11:51:19 2017 KojiUpdateIMCRF AM stabilization box pulled out

For a comparison: OMC ELOG 238

  12780   Tue Jan 31 22:07:13 2017 gautamUpdateIMCRF AM stabilization box revamp

I've added the schematic of the RF AM stabilization board to the 40m PSL document tree, after having created a new DCC document for our 40m edits. Pictures of the board before and after modification will also be uploaded here...

  12784   Wed Feb 1 16:45:56 2017 LydiaUpdateIMCRF AM stabilizer box Modification Plan

Here's what I'm planning to do to the RF AM stabilizer box. I'm going to take out several of the components along the path to the EOM (comments in green), including the dead ERA-4 and ERA-5 amplifiers, the variable attenuator which is controlled by a switch that can't be accessed outside the box, and the feedback path from the daughter board servo. I'm arranging things so that the output of the HELA-10 does not exceed the maximum output power. 

I wasn't quite as sure what to do about the path to the ASC box (comments in blue). I talked with Gautam and he said this gets split equally between several singals, one of which goes to the LO of the demod board which expects -10 dBm and currently gets -12 dBm (can go up to -8 by turning switch). So maybe we don't actually want the signal to be anywhere near +27 dBm at the output. The plans for the box are here, it looks like +27 in will end up with +10 at each output, which is way more than what's currently coming out. But maybe this needs to be increased to match the other path? 

Also we haven't measured the actual response of the variable attenuator U4 for various switch positions; it's the same model as the one I'm removing from the EOM path and that one had slightly different behavior for different switch positions than what the spec sheet says. Same goes for the HELA-10 units along this path: what is their actual gain? So perhaps these should be measured and then a single attenuator should be chosen to get the right output signal level. Alternatively it could just be left alone, if it is at an OK level right now. Advice on what to do here would be appreciated.  

I'll work on the EOM path tonight and wait for feedback on the rest of it. 

EDIT: Gautam pointed out that there's some insertion loss from the components I'll be removing that hasn't been accounted for. Also the plans have been updated to reflect that I'm replacing AT5 with a 1dB attenuator (from 6 dB). 

Attachment 1: RF_AM_stabilizer_modification.pdf
RF_AM_stabilizer_modification.pdf
  12785   Wed Feb 1 20:49:34 2017 ranaUpdateIMCRF AM stabilizer box Modification Plan

I suggest:

  1. Disable the path which goes to the two spare outputs. Replace the ERA-5 with a 50 Ohm resistor to terminate that path. Make sure the ERA bias voltage is not shorting into something.
  2. Remove the ERA amps from the ASC path and remove the switch. Make it fixed gain such that we get +27 dBm out of the front.
  3. Put the ASC output into the 1U multi-splitter box and attenuate those outputs so that they supply ~0 dBm to the 2 WFS and the LSC Demod board.

I think this then allows us to have the low noise OCXO signals everywhere with enough oomph.

 

  12786   Wed Feb 1 23:13:30 2017 LydiaUpdateIMCRF AM stabilizer box Modification Plan

I made some of the changes. Gautam and I will finish tomorrow. 

While I was soldering the sharpest tip of the soldering iron (the one whose power supply shows the temperature) stopped working and I switched to a different one. Not sure how to fix this. 

Do we want to replace all of the removed ERA's with 50 Ohm resistors, or just the one along the spare output path? I shorted one of them with a piece of wire and left all the others open. 

I couldn't get one of the attenuators off (AT1, at beginning of ASC path). In trying I messed up the solder pad. Part of the connecting trace on the PCB board is exposed so we should be able to fix it. 

  5364   Wed Sep 7 22:17:04 2011 ranaUpdateIOORF Amp for EOM on PSL Table

After Steve pointed out the 'deep hoop' issue, we decided to examine putting an RF Amp on the PSL table, between the RF combiner and the triple resonant box.

This will reduce the chances of standing waves in the cables and reduce the radiation induced pick-up in the RF PD and Demod electronics.

We would like to send ~10 dBm from the distribution box to the combiner. We also want to able to get as much as ~33 dBm of drive at 11 and 55 MHz. So the amp should have a gain of ~20-30 dB and an operating range of 10-100 MHz.

Also desirable are low distortion (high IP3) and good reverse isolation ( > 40 dB).

Some possibilities so far (please add your RF Google Results here):

1) Mini-Circuits ZHL-1-2W-S:  G = +32 dB, Max Out = +33 dBm, NF = 6 dB, Directivity = 25 dB

2) Mini-Circuits TIA-1000-1R8:  G=+40 dB, Max Out = +36 dBm, NF = 15 dB   (AC Powered, Inst. Amp), Directivity = 58 dB.

3) Mini-Circuits ZHL-2-8: G = +27dB, Max out = +29 dBm, NF = 6dB, Directivity = 32 dB

4) RFbay MPA-10-40: G = +40dB, Max Out = + 30 dBm, NF = 3.3 dB, Rev Iso = 23 dB

5) No proper stuff from Teledyne Couger

 

  5372   Fri Sep 9 19:15:17 2011 ranaUpdateIOORF Amp for EOM on PSL Table

Quote:

After Steve pointed out the 'deep hoop' issue, we decided to examine putting an RF Amp on the PSL table, between the RF combiner and the triple resonant box.

5) No proper stuff from Teledyne Couger

 

By looking at what Daniel used in the low noise EOM Driver for aLIGO, we found the A2CP2596 from Cougar.

G = +24 dB, NF = 5 dB, Max Out = +37 dBm. It comes in a 2-stage SMA connector package. I've asked Steve to order 2 of them with the appropriate heatsinks.

  12189   Thu Jun 16 12:06:59 2016 ericqUpdateLSCRF Amp installed at POY11 RF output

I have installed a ZFL-500LN on the RF output of POY11. This should reduce the effect of the CM board voltage offsets by increasing the size of the error signal coming into the board. Checking with an oscilloscope at the LSC rack, the single arm PDH peak to peak voltage was something like 4mV, now it is something like 80mVyes

The setup is similar to the REFL165 situation, but with the amplifier in proximity with the PD, instead of at the end of a long cable at the LSC rack. 

The PD RF output is T'd between an 11MHz minicircuits bandpass filter and a 50 Ohm terminator (which makes sure that signals outside of the filter's passband don't get reflected back into the PD). The output of the filter is connected directly to the input of the ZFL-500LN, which is powered (temporarily) by picking off the +15V from the PD interface cable via Dsub15 breakout. (I say temporarily, as Koji is going to pick out some fancy pi-filter feedthrough which we can use to make a permanent power terminal on the PD housing.)

The max current draw of this amplifier is 60mA. Gazing at the LSC interface (D990543), I think the +15V on the DSUB cable is being passed from the eurocard crate; I don't see any 15V regulator, so maybe this is ok...

The free swinging PDH signal looked clean enough on a scope. Jamie is doing stuff with the framebuilder, so I can't look at spectra right now. However, turning the POY whitening gain down to +18dB from +45dB lets the Y arm lock on POY with all other settings nominal, which is about what we expect from the nominal +23dB gain of the amplifier.

I would see CM board offsets of ~5mV before, which was more a little more than a linewidth before this change. Now it will be 5% of that, and hopefully more manageable.

  1959   Fri Aug 28 12:56:17 2009 YoichiUpdateLockingRF CARM hand off problem
Last night, the lock script proceeded to the RF CARM hand-off about half of the time.
However, the hand off was still unsuccessful.

It failed instantly when you turn on the REFL1 input of the CM board, even
when the REFL1 input gain was very low, like -28dB.

I went to the LSC rack and checked the cabling.
The output from the PD11_I (REFL_2) demodulation board is split
into two paths. One goes directly to the ADC and the other one goes
to an SR560. This SR560 is used just as an inverter. Then
the signal goes to the REFL1 input of the CM board.

I found that the SR560 was set to the A-B mode, but B input was open.
This made the signal very noisy. So I changed it to A only mode.
There was also a 1/4 attenuator between the PD11_I output and the SR560.
I took it out and reduced the gain of SR560 from 10 to 2.
These changes allowed me to increase the REFL1 gain to -22dB or so.
But it is still not enough.

I wanted to check the CM open loop TF before the hand-off, but I could
not do that because the lock was lost instantly as soon as I enabled the
test input B of the CM board.
Something is wrong with the board ?

Using the PD11_I signal going into the ADC, I measured the transfer functions
from the CM excitation (digital one) to the REFL_DC (DC CARM signal) and PD11_I.
The TF shapes matched. So the PD11_I signal itself should be fine.

We should try:
* See if flipping the sign of PD11_I signal going to REFL1 input solve the problem.
* Try to measure the CM analog TF again.
* If the noise from the servo analyzer is a problem, try to increase the input gains
of the CM board and reduce the output gain accordingly, so that the signal flowing
inside the CM board is larger.
  1960   Fri Aug 28 13:49:07 2009 robUpdateLockingRF CARM hand off problem

Quote:
Last night, the lock script proceeded to the RF CARM hand-off about half of the time.
However, the hand off was still unsuccessful.

It failed instantly when you turn on the REFL1 input of the CM board, even
when the REFL1 input gain was very low, like -28dB.

I went to the LSC rack and checked the cabling.
The output from the PD11_I (REFL_2) demodulation board is split
into two paths. One goes directly to the ADC and the other one goes
to an SR560. This SR560 is used just as an inverter. Then
the signal goes to the REFL1 input of the CM board.

I found that the SR560 was set to the A-B mode, but B input was open.
This made the signal very noisy. So I changed it to A only mode.
There was also a 1/4 attenuator between the PD11_I output and the SR560.
I took it out and reduced the gain of SR560 from 10 to 2.
These changes allowed me to increase the REFL1 gain to -22dB or so.
But it is still not enough.

I wanted to check the CM open loop TF before the hand-off, but I could
not do that because the lock was lost instantly as soon as I enabled the
test input B of the CM board.
Something is wrong with the board ?

Using the PD11_I signal going into the ADC, I measured the transfer functions
from the CM excitation (digital one) to the REFL_DC (DC CARM signal) and PD11_I.
The TF shapes matched. So the PD11_I signal itself should be fine.

We should try:
* See if flipping the sign of PD11_I signal going to REFL1 input solve the problem.
* Try to measure the CM analog TF again.
* If the noise from the servo analyzer is a problem, try to increase the input gains
of the CM board and reduce the output gain accordingly, so that the signal flowing
inside the CM board is larger.



I'd bet it's in a really twitchy state by the time the script gets to the RF CARM handoff, as the script is not really validated up to that point. It's just the old script with a few haphazard mods, so it needs to be adjusted to accomodate the 15% power drop we've experienced since the last time it was locked.

The CM servo gain needs to be tweaked earlier in the script--you should be able to measure the AO path TF with the arm powers at 30 or so. I was able to do this with the current SR785 setup earlier this week without any trouble.

The 1/4 attenuator is there to prevent saturations on the input to the SR560 when there's still a CARM offset.

Not sure if flipping the sign of PD11 is right, but it's possible we compensated the digital gains and forgot about it. This signal is used for SRCL in the initial acquisition, so we'd have noticed a sign flip.
  4670   Mon May 9 17:23:25 2011 SureshUpdateRF SystemRF Cables near LSC Rack

[Steve, Suresh]

We started to clean up the RF cables (heliax and PD interface cables)  at the LSC rack.

We have pulled out all the RF cables from the small hole on the side-board close to floor.  Passing the cables through this hole makes some of the cables much too short for good strain relief.  So we removed the side panel on the vacuum tube side and are going to pass the cables into the rack from there at about waist height.  We now have plenty of cable lengths to tie them off to the rack at several points.

We have traced all the available Heliax cables and have attached blank tags to them.  We have allocated some cables to REFL11, REFL55 and AS55.  These are therefore back in working order.  We have also taken stock of the available PD interface cables.  They do not have consistent names on both ends of the cable and we will identify and label the ends tomorrow.

MC is locked.  The auto-locker works fine.

Handing over the system for night time interferometer work now.  Will continue with the cabling tomorrow.

 

  4315   Thu Feb 17 14:17:27 2011 SureshUpdateElectronicsRF Distribution box and REFL11

 

The Distribution box is several steps nearer to completion.

 

1) Soldered capacitors and DC power lines for four units of the distribution box.

2) mounted all the components in their respective places.

3) Tomorrow we prepare the RF cables and that is the last step of the mechanical assembly. 

4) we plan to test both the generator and distributon parts together.

 

 

 

REFL 11

 

[Kevin, Suresh]

Kevin took a transfer function of the newly assembled PD and noticed that the frequency has shifted to 14.99  freom 11. MHz.

We needed to find the current RLC combination.  So we  removed the ferrite core from L5 rendiring it to its aircore value of  0.96/muH. We then used this to find the Capacitance of the PD (117pF)

We  used this value to compute the inductance required to achieve 11.065MHz  which turned out to be 1.75microH.

This was not reachable with the current L5 which is of the type  143-20J12L (nominal H=1.4 micro Henry).

We therefore changed the inductor to SLOT 10 -3-03. It is a ferrite core, shielded inductor with a plasitc sleeve. Its nomial valie is 1.75 microH

We then tested the DC output to see if here is a response to light. There was nonel. l

The problem was traced to the new inductor.  Surprisingly the inductor coil had lost contact with the pins.

I then replacd the inductor and checked again.  The elecronics seems to work okay..   but there is a very small signal 0.8mV for 500microW. 

There seems to be still something wrong with the PD or its electronics.

 

 

  4579   Thu Apr 28 07:14:34 2011 SureshUpdateRF SystemRF Distribution box installed

RF Distribution box has been mounted in the 1Y2 rack and is ready for use.

 

P4280066.JPG

The box receives 11 and 55 MHz Demod Signals from the RF source located in the 1X2 rack.

  4342   Wed Feb 23 08:53:58 2011 SureshUpdateElectronicsRF Distribution box: Output power levels

We wish to have roughly 2 dBm of output power on each line coming out of the RF distribution box.  So I adjusted the attenuators inside the box to get this.

I also looked at why the 2x output looked so distorted and found that the input power was around 17 dBm whereas the maximum allowed (as per the datasheet of Minicircuits MK-2) is 15dBm.  So I increased the attentuation on its input line to 5dBm (up by 2dBm)  The input power levels are around 14.6dBm now  and the distortion has come down considerably.  However the net output on the 2x lines is now down to 0.7dBm.  We will have to amplify this if we need more power.

The schematic and the power output are now like this:

RF_Distribution_box_23rdFeb.jpg


  4336   Tue Feb 22 00:41:34 2011 SureshUpdateElectronicsRF Distribution box: assembly completed

The mechanical assembly of RF distribution box is 99% complete.  Some of the components may be bolted to the teflon base plate if needed. 

All RF cables and DC voltage supply lines have been installed and tested.  I removed the terminal block which was acting as a distribution box for the common zero voltage line.  Instead I have used the threaded holes in the body of each voltage regulator.   This allows us to keep the supply lines twisted right up to the regulator and keeps the wiring neater.  The three regulator bodies have been wired together to provide a common zero potential point. 

I did a preliminary test to see if everything is functioning. All units are functioning well.  The output power levels may need to be adjusted by changing the attenuators. 

The 2x frequency multiplier outputs are not neat sine waves.  They seem to produce some harmonics, unlike the rest of the components.

I will post the measured power output at each point tomorrow.  The RF power meter could not be found in the 40m lab.  We suspect that it has found its way back to the PSL lab.

 

  4337   Tue Feb 22 11:53:38 2011 steveUpdateElectronicsRF Distribution box: assembly completed

Quote:

The mechanical assembly of RF distribution box is 99% complete.  Some of the components may be bolted to the teflon base plate if needed. 

All RF cables and DC voltage supply lines have been installed and tested.  I removed the terminal block which was acting as a distribution box for the common zero voltage line.  Instead I have used the threaded holes in the body of each voltage regulator.   This allows us to keep the supply lines twisted right up to the regulator and keeps the wiring neater.  The three regulator bodies have been wired together to provide a common zero potential point. 

I did a preliminary test to see if everything is functioning. All units are functioning well.  The output power levels may need to be adjusted by changing the attenuators. 

The 2x frequency multiplier outputs are not neat sine waves.  They seem to produce some harmonics, unlike the rest of the components.

I will post the measured power output at each point tomorrow.  The RF power meter could not be found in the 40m lab.  We suspect that it has found its way back to the PSL lab.

 

 http://www.timesmicrowave.com/wireless/index.shtml  

Frank is recommending these PhaseTrack-210 as phase stable low loss rf coax cables.

  3529   Mon Sep 6 22:09:11 2010 AlbertoUpdateElectronicsRF Frequency Generation Box heat sink installed and tested

Last week I noticed that the high power amplifiers in the Frequency Generation Box became hot after 2 hours of continuous operation with the lid of the box closed. When I measured their temperature it was 57C, and it was still slowly increasing (~< 1K/hr).
According to the data sheet, their maximum recommended temperature is 65C. Above that their performances are not guaranteed anymore.

These amplifiers aren't properly dissipating the heat they produce since they sit on a plastic surface (Teflon), and also because their wing heat dissipator can't do much when the box is closed. I had to come up with some way to take out their heat.
The solution that I used for the voltage regulators (installing them on the back panel, guaranteeing thermal conduction but electrical isolation at the same time) wouldn't be applicable to the amplifiers.

I discussed the problem with Steve and Koji and we thought of building a heat sink that would put the amplifier in direct contact with the metal walls of the box.
After that, on Friday I've got Mike of the machine shop next door to make me this kind of L-shaped copper heat sink:

DSC_2467.JPG

On Saturday, I completely removed the wing heat dissipator, and I only installed the copper heat sink on top of the amplifier. I used thermal paste at the interface.

DSC_2433.JPG
I turned on the power, left the lid open and monitored the temperature again. After 2 hours the temperature of the amplifier had stabilized at 47C.

Today I added the wing dissipator too, and monitored again the temperature with the lid open. then, after a few hours, I closed the the box.
I tracked the temperature of the amplifier using the temperature sensors that I installed in the box and which I have attached to the heat sink.
I connected the box temperature output to C1:IOO-MC_DRUM1. With the calibration of the channel (32250 Counts/Volt), and Caryn's calibration of the temperature sensor (~110F/Volt - see LIGO DOC # T0900287-00-R), the trend that I measured was this:

2010-09-06_FreqBoxAmplifierTemperatureTrend.png

Conclusion
The heat sink is avoiding the amplifier to overheat. The temperature is now compatible with that of the other component in the box (i.e., crystal oscilaltors, frequency multiplier).
Even with the lid closed the temperature is not too high.

Two things remain untested yet:
1) effect of adding a MICA interface sheet between the heat sink and the wall of the chassis. (necessary for gorund isolation)
2) effect of having all 3 amplifiers on at the same time

I am considering opening air circulation "gills" on the side and bottom of the chassis.

Also we might leave the box open and who ever wants can re- engineer the heat sink.

For posterity.
- Ideally we would like that the heat sink had the largest section area. A brick of metal on top the amplifier would be more effective. Although it would have added several pounds to the weight of the box.
- We need these amplifiers in order to have the capability to change the modulation depth up to 0.2, at least. The Mini-Circuit ZHL-2X-S are the only one available off-the-shelf, with a sufficiently low noise figure, and sufficiently high output power.

  4284   Mon Feb 14 07:37:13 2011 SureshUpdateElectronicsRF Generation Box: capacitors across power lines

 

There were several parts in this box which did not have shunting capacitors across their input power lines.  Only the four RF amps (ZHL-2) had them.

I soldered two capacitors (100 microF electrolytic and 150pF dipped mica) across the power supply lines of each of the following units:  11MHz oscillator, 29.5 MHz oscillator,  Wenzel 5x frequency multiplier and the 12x RF amplifier (ZHL-1HAD).

It was quite difficult to reach the power inputs of these units as some of them were very close to the inner walls of the box.  To access them I undid the front panel and found that there were several very taut RF cables which prevented me from moving the front panel even a little.

I had to undo some of the RF cables and swap them around till I found a solution in which all of them had some slack.  At the end I checked to make sure that the wiring is in accordance with the schematic present here.

 

  2994   Wed May 26 17:10:09 2010 AlbertoUpdate40m UpgradingRF Generation box

This is how the RF generation box might soon look like:

Visio-frequencyGenerationBox_wiringSchematic.png

A dedicated wiki page shows the state of the work:

http://lhocds.ligo-wa.caltech.edu:8000/40m/Upgrade_09/RF_System/frequency_generation_box#preview

  321   Mon Feb 18 12:04:39 2008 AlbertoUpdateElectronicsRF Monitor (StocMon)
I put the amplifiers next to the monitor on the PSL table, layed the power and the RF SMA cables out to the rack. I'm powering the box and the amplifiers with the power supply, waiting for someone to show me tomorrow how to connect it to the Sorensen (Steve, Ben?).

I'm ready to hook up the channels into EPICS.
Attachment 1: DSC_0443.JPG
DSC_0443.JPG
  331   Fri Feb 22 08:29:07 2008 AlbertoUpdateElectronicsRF Monitor (StocMon)

Quote:
I put the amplifiers next to the monitor on the PSL table, layed the power and the RF SMA cables out to the rack. I'm powering the box and the amplifiers with the power supply, waiting for someone to show me tomorrow how to connect it to the Sorensen (Steve, Ben?).

I'm ready to hook up the channels into EPICS.


Me and Ben Abbot were plugging the cables that power that RF Monitor box into the PSL rack when inadvertently we made some arcs spark between the pins on the back of one of the ADC. Somehow that made the laser shut down although the MOPA stayed on. We also notice some smell of burn.

Later on, after several failed attempts, Rob, Ben and Steve could restart the laser. It took some times because the written procedure to start the chiller is not very precise.
  332   Fri Feb 22 08:33:18 2008 AlbertoUpdateElectronicsRF Monitor (StocMon)

Quote:
I put the amplifiers next to the monitor on the PSL table, layed the power and the RF SMA cables out to the rack. I'm powering the box and the amplifiers with the power supply, waiting for someone to show me tomorrow how to connect it to the Sorensen (Steve, Ben?).

I'm ready to hook up the channels into EPICS.


With Ben, we hooked up the RF Monitor box into the PSL rack and created 4 EPICS channels for the outputs:

C1:IOO_RF_STOC_MON_33
C1:IOO_RF_STOC_MON_133
C1:IOO_RF_STOC_MON_166
C1:IOO_RF_STOC_MON_199

The power cable bringing +15V to the preamplifier on the PSL table should be replaced eventually.
  334   Fri Feb 22 11:13:15 2008 robUpdateElectronicsRF Monitor (StocMon)

Quote:
It took some times because the written procedure to start the chiller is not very precise.


It is actually very precise. Precisely wrong.
  347   Thu Feb 28 19:49:21 2008 robUpdateElectronicsRF Monitor (StocMon)


Quote:

With Ben, we hooked up the RF Monitor box into the PSL rack and created 4 EPICS channels for the outputs:

C1:IOO_RF_STOC_MON_33
C1:IOO_RF_STOC_MON_133
C1:IOO_RF_STOC_MON_166
C1:IOO_RF_STOC_MON_199

The power cable bringing +15V to the preamplifier on the PSL table should be replaced eventually.


I changed the names of these channels to the more appropriate (and informative, as they're coming from the RFAMPD):

C1:IOO-RFAMPD_33MHZ
C1:IOO-RFAMPD_133MHZ
C1:IOO-RFAMPD_166MHZ
C1:IOO-RFAMPD_199MHZ

I also added them in an aesthetically sound manner to the C1IOO_LockMC.adl screen and put them in trends. Along the way, I also lost whatever Alberto had done to make these monitors read zero when there's no light on the diode. It doesn't appear to be written down anywhere, and would have been lost with a reboot anyway. We'll need a more permanent & automatable solution for this.
  246   Thu Jan 17 18:22:14 2008 AlbertoUpdateElectronicsRF Monitor Band-pass Filter
After we finalized the schematic for the RF monitor board based on buffered LC resonators, on Richard Abbott's suggestion to avoid the complication brought in by the fast op-amps, we gave another chance to the a passive configuration of the band-pass filter based on a Chebyshev topology. Rich and Ben gave me an old but very powerful software tool to design that kind of filters and showed me the way to circumvent many hassles in making RF test boards.

I made a test circuit for the 166MHz line (see attached schematic), using tunable inductors. The TF are also attached.
We get more than 20 dB of isolation after 33MHz (with a loss of only few dB at the resonance - it could be less), which is enough for all the other frequencies (33,133,199 MHz) but we would like more for the 166. We are going to add one or two extra orders to the filter.

We also have to understand the spike at about 320Mhz and eventually somehow get rid of it.


Alberto
Attachment 1: RF166Mhz.png
RF166Mhz.png
Attachment 2: Chebyshevb.png
Chebyshevb.png
Attachment 3: Chebyshev2b.png
Chebyshev2b.png
  248   Fri Jan 18 11:53:50 2008 AlbertoUpdateElectronicsRF Monitor Band-pass Filter
The response is asymmetric and on the left side of the peak, we have at least 33dB within 33Mhz, which is enough for all the frequencies. We probably don't need an higher order filter but just low pass filters in series.

The spike at 320MHz doesn't depend on the circuit board. It's either the cables, their connection, or the splitters.

Note that the frequency of this test circuit has still to be tuned exactly at 166MHz (now it's 149).


Alberto



Quote:
After we finalized the schematic for the RF monitor board based on buffered LC resonators, on Richard Abbott's suggestion to avoid the complication brought in by the fast op-amps, we gave another chance to the a passive configuration of the band-pass filter based on a Chebyshev topology. Rich and Ben gave me an old but very powerful software tool to design that kind of filters and showed me the way to circumvent many hassles in making RF test boards.

I made a test circuit for the 166MHz line (see attached schematic), using tunable inductors. The TF are also attached.
We get more than 20 dB of isolation after 33MHz (with a loss of only few dB at the resonance - it could be less), which is enough for all the other frequencies (33,133,199 MHz) but we would like more for the 166. We are going to add one or two extra orders to the filter.

We also have to understand the spike at about 320Mhz and eventually somehow get rid of it.


Alberto
Attachment 1: Chebyshevb.png
Chebyshevb.png
  10152   Tue Jul 8 15:07:24 2014 NichinHowToElectronicsRF Multiplexer in rack 1Y1

The RF multiplexer is configured as shown in the figure. It is now effectively a 15x1 RF mux.

RF_Multiplexers.png

To select a required channel:

Run the script as shown below 

/opt/rtcds/caltech/c1/scripts/general/rfMux.py

>python rfMux.py ch11

For channel 10 to 16, you can just enter the required channel number and it is routed to the output.

For channel 1 to 8, you only need to input the required channel number as above. No need to run the code again to select ch9 after selecting ch1-8

 

How the NI-8100 controller works:

Whenever any channel of one switch is selected, the output of the other switch is set to its ch0 (ch1 and ch9 in the figure).

So selecting ch1-8 will automatically select ch9 as output for the other switch. IF you send a command to select ch9 afterwards, the first switch will be automatically set to ch1 and not stay on what you had selected before.

  9005   Tue Aug 13 11:54:40 2013 Alex ColeHowToElectronicsRF PD Fiber-Coupled Laser Operation

This post pertains to the fiber-coupled diode laser mounted in rack 1Y1.

To turn the laser on, first turn the power supply's key (red) to the clockwise. Then make sure that the laser is in "current" mode by checking that the LED next to "I" in the "Laser Mode" box in lit up. If the light is not on, press the button to the right of the "I" light until it is. Now press the output button (green). This is like removing the safety for the laser. Then turn the dial (blue) until you have your desired current. Presently, the current limit is set to around 92 mA.

To turn the laser off, dial the current back down to 0mA and turn the key (red) counterclockwise.

Attachment 1: photo_(4).pdf
photo_(4).pdf
  1929   Wed Aug 19 18:02:22 2009 JenneUpdateLSCRF PDs aligned

All of the LSC RF PDs have been aligned.  I didn't really change much of anything, since for all of them, the beam was already pretty close to center.  But they all got the treatment of attaching a Voltmeter to the DC out, and adjusting the steering mirror in both pitch and yaw, finding where you fall off the PD in each direction, and then leave the optic in the middle of the two 'edges'.

Before aligning each set (PO, Refl, AS), I followed the procedure in Rob's new RF photodiode Wiki Page

Also, for superstitious reasons, and in case I actually bumped them, I squished all of the ribbon cable connectors into the PDs, just in case.

  10133   Mon Jul 7 10:35:43 2014 JenneUpdateElectronicsRF PDs needed

Quote:

 REFL33, AS55, REFL55,REFL165,REFL11,POX11,POP22

There were quite a few more demodulator units labelled with PD names. Do any of them need to be included in the automated frequency response measurement system? Please let me know so that I can include them to the RF switch and check them for proper illumination, which i will do for all the above PDs next week.

 In the order that makes more sense to me, it looks like you have:

REFL11, REFL33, REFL55, REFL165,

AS55

POX11

POP22

We don't really need POP22 right now, although we do want the facility to do both POP22 and POP110 for when we (eventually) put in a better PD there.  Also, we want cabling for POP55, so that we can illuminate it after we re-install it.  If we're working on 2f PDs, we might as well consider AS110 also, although I don't know that there was a fiber layed for it.  The big one that you're missing is POY11.

  10143   Mon Jul 7 17:20:09 2014 NichinUpdateElectronicsRF PDs needed

Quote:

Quote:

 REFL33, AS55, REFL55,REFL165,REFL11,POX11,POP22

There were quite a few more demodulator units labelled with PD names. Do any of them need to be included in the automated frequency response measurement system? Please let me know so that I can include them to the RF switch and check them for proper illumination, which i will do for all the above PDs next week.

 In the order that makes more sense to me, it looks like you have:

REFL11, REFL33, REFL55, REFL165,

AS55

POX11

POP22

We don't really need POP22 right now, although we do want the facility to do both POP22 and POP110 for when we (eventually) put in a better PD there.  Also, we want cabling for POP55, so that we can illuminate it after we re-install it.  If we're working on 2f PDs, we might as well consider AS110 also, although I don't know that there was a fiber layed for it.  The big one that you're missing is POY11.

 A new RF cable has been included for POY11. Cabling for POP55 and POP110 might or might not exist. I will check and report it.

  4048   Mon Dec 13 21:03:30 2010 KevinUpdateElectronicsRF Photodiode Characterizations

[Koji, Jenne, Kevin]

Jenne worked on fixing REFL11 last week (see elog 4034) and was able to measure an electrical transfer function. Today, I tried to measure an optical transfer function but REFL11 is still not responding to any optical input. I tried shining both the laser and a flashlight on the PD but could not get any DC voltage.

I also completed the characterizations of POX. I redid the optical transfer function and shot noise measurements. I also took a time series of the RF output from the PD when it was powered on with no light. This measurement shows oscillations at about 225 MHz. I also measured the spectrum with no light which also shows the oscillations at 225 MHz and smaller oscillations at ~455 MHz.

The plots can be found at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/POX?action=show.

ELOG V3.1.3-