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ID Date Author Type Category Subjectup
  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.

  4051   Tue Dec 14 04:14:53 2010 ranaUpdateElectronicsRF Photodiode Characterizations

This is looking better, but the fit data for the TF should be plotted along with the data. The data should be made up of points and the fit a line.

For the fit, we should have the Q of the main resonance as well as the peak height of the main resonance and the values of the gain at the notch frequencies.

Also the peak as well as the notches should have the frequencies fit for and labeled. In principle, you can make the plot on the wiki have all of the data. Then in the end we can print the plot in a small size and glue it to the PD's backside.

  4503   Fri Apr 8 01:05:45 2011 SureshUpdateRF SystemRF Source Harmonics

 

 The measured power levels of the RF source harmonics are given below:

 

 

We are considering inclusion of bandpass filters centered on 11 and 55 MHz  to suppress the harmonics and meet the requirements specified in Alberto's thesis (page 88).

 

Attachment 1: RF_Source_Harmonics_Sheet1.pdf
RF_Source_Harmonics_Sheet1.pdf RF_Source_Harmonics_Sheet1.pdf RF_Source_Harmonics_Sheet1.pdf RF_Source_Harmonics_Sheet1.pdf
  4557   Fri Apr 22 09:05:53 2011 SureshUpdateRF SystemRF Source Harmonics
As seen in the previous measurement the first harmonic of both the 11 MHz and 55 MHz outputs are about 30dB
higher than desired.  In an attempt to attenuate these and higher harmonics I introduced SBP-10.7 filters into
the 11MHz outputs and SLP-50 filters into the 55 MHz outputs.
Then I measured the height of the harmonics again and found that they were suppressed as expected.  Now harmonic
at 22 MHz is 58dB lower than the 11 MHz fundamental.  And the 110 MHz is lower by 55 dB compared to the 55 MHz
fundamental.  None of the higher harmonics are seen => they are below 70dB

SLP-50 has an insertion loss(IL) of 4.65 dB and Return Loss(RL) of 3dB.  It would be better to use SBP-60
(IL=1.4 dB and RL=23dB)

The filter on the 11 MHz lines is okay. The SBP-10.7 has IL=0.6 dB and RL=23 dB.
  4559   Fri Apr 22 10:28:22 2011 ranaUpdateRF SystemRF Source Harmonics
You should be able to resolve the other harmonics by decreasing the IF BW or RBW on the analyzer. Even though
they're OK, its useful to have the final measurement of all of them in some kinds of physical units (like dBm, but
not dBm/Hz or dB or dBcubits).
  4628   Wed May 4 15:39:32 2011 SureshUpdateRF SystemRF Source Harmonics


I have measured the RF source harmonics in dBm using the HP 8591E spectrum analyser. There is a small discrepancy (< 1 dBm) in the value of RF power shown by the power meter and the HP8591E. This is probably due to the loss of calibration over time.

Initial problem I faced was that when we try to measure the weak harmonics, many below -50dBm we have to choose a small band as advised by Rana. However due to the large amplitide of the fundamental typically around 15dBm or so, the preamp on the spectrum analyser becomes saturated and nonlinear. This gives rise spurious harmonics not present in the source but are rather an aritifact of measurement. The power in harmonics to avoid this I used filters to selectively attenuate the fundamental component (11 or 55 MHz) and then measure the weak harmonics.

However the filters proved difficult to use, because over their stop-band they do not have an input impedance of 50 Ohm. As a result they produce unreliable power measurements for those frequency components which are within the stop band.

To get around this problem I used a suitable attenuator so that even when the internal attenuation is decreased the preamp does not saturate

All the measurements are recorded in the attached document. Pages 4 and 5 give the reliable measurements with the attenuator.

Notes:
1) At times we can see the 29.5 MHz component reflected back from the triple resonant EOM driver.
2) In the 29.5 MHz source output there is a forest of peaks around 100 MHz, which disappear after passing through the AM stabiliser. This suggests that they are associated with AM modulation and have been removed by the stabilizer. But I did not check this further.










Quote:
You should be able tosd resolve the other harmonics by decreasing the IF BW or RBW on the analyzer. Even though
they're OK, its useful to have the final measurement of all of them in some kinds of physical units (like dBm, but
not dBm/Hz or dB or dBcubits).
Attachment 1: RF_Harmonics_Sheet1.pdf
RF_Harmonics_Sheet1.pdf RF_Harmonics_Sheet1.pdf RF_Harmonics_Sheet1.pdf RF_Harmonics_Sheet1.pdf RF_Harmonics_Sheet1.pdf RF_Harmonics_Sheet1.pdf
  4657   Sat May 7 10:59:11 2011 SureshUpdateRF SystemRF Source filters changed

 

The SLP-50 filters which were on the 55 MHz lines have been replaced with the SBP-60.  Their respective characteristics are given below:

 

at 55MHz Insertion loss (dB) Return Loss (dB)
SLP-50 4.65 1.5
SBP-60 1.36 23

 

SBP-60 has lower insertion loss and higher return loss.  

This may however change the phase of I and Q in the demod boards and they will therefore need to be readjusted.  Currently the output power level of 55 MHz demod is at 2dBm, whereas it ought to be at 6dBm.   I have not yet corrected that.  Once that is completed Kiwamu will adjust the phases.

 I shifted the temperature sensor to a new location.  See the photograph below.  I noticed that the higher temperature is reached on the side where there are two RF Amps.  So it would be better to check the temperature of that  area and make sure that it remains well below 65 deg.  The operating maxium is 65deg C

 

Here is a picture of the new RF source layout.

RF_Source_Schematic.png

And here is a photograph of it

RF_Source.jpg

 

  4578   Thu Apr 28 06:46:30 2011 SureshUpdateRF SystemRF Source installed

RF Source box has been mounted in the 1X2 rack. 

P4280064.JPG

 

Heliax cables have been directly attached to the box and anchored on the side of the 1X2 rack.  Here is a list of Helix cables which have been connected so far.

 

Cables old name New name From -> To
1 133 MHz 11 Mhz Demod 1X2 to 1Y2 rack
2 199 MHz 55 MHz Demod 1X2 to 1Y2 rack
3 166 EOM 11 MHz EOM 1X2 to PSL table
4 33 EOM 55 MHz EOM 1X2 to PSL table
5 REFL 33 AS11 AS table to 1Y2

 

  4558   Fri Apr 22 09:25:43 2011 SureshUpdateRF SystemRF Source: Temperature sensor relocated

RF Amp operating temperature

Earlier measurement reported by Alberto in LIGO-T10004-61-v1 based on the LM34 temperature sensor were lower than that shown by placing a calibrated thermocouple sensor directly on the heat sink by about 5deg C. The difference probably arose because the LM34 was located on a separate free-hanging copper sheet attached to the RF Amp by a single screw, resulting in a gradient across the copper strip.   I tried to move the LM34 which was glued down, but broke the leads in the process.  I then replaced it with another one mounted much closer to the heat sink and held it down with a copper-strip clamp.  There is no glue involved and there is heatsink compound between the flat surface of the LM34 and the heatsink.  Picture attached. 

  The picture also shows the new filters which have been put in place to reduce the harmonics.  Note that the SBP-10.7 which was to go on the 11 MHz Demod output is located much farther upsteam due to space constraints.

P4220056.JPG

  4711   Fri May 13 01:51:56 2011 SureshUpdateRF SystemRF Status update

I have posted the attached RF status update and 1Y2 rack layout to the svn.

Attachment 1: 1Y2_Rack_Layout.pdf
1Y2_Rack_Layout.pdf
Attachment 2: RF_Work_Status.pdf
RF_Work_Status.pdf
  8979   Wed Aug 7 15:51:53 2013 Alex ColeConfigurationElectronicsRF Switch Change

For the photodetector frequency response project, our new RF Switch Chassis (NI pxie-1071) arrived today. I took the switches out of the old chassis (Note for future generations: you have to yank pretty darn hard) and put them in the new chassis, which I mounted in rack 1Y1 as pictured. 

The point of this new chassis is that its controller is compatible with our control room computer setup. We will be able to switch the chassis using TCP/IP or telnet, aiding in our automation of the measurement of photodetector frequency response.

Attachment 1: photo_(2).JPG
photo_(2).JPG
  3532   Tue Sep 7 13:31:49 2010 AlbertoUpdateElectronicsRF System - Frequency Distribution Box - Priority Plan

We need a distribution unit in the LSC rack to: 1) collect the demod signals coming from the Frequency Generation Box 2) adjust the power level 3) generate 2nd harmonics (for POP) 4) distribute the demod signals to the single demodulation boards.

The base line plan is the following:

Visio-RFsystem_plan_distributiont.png

The box can be build up gradually, but the priority goes to these parts:

 RFsystem_plant_distribution_priority.png

I need help for this work. I know exactly how to do it, I just don't have the time to do it all by myself.

 Besides the Distribution Box, the demodulation part of the upgrade would still require two steps:

1) upgrade the Band Pass Filters of the demodulation boards (I have all the parts)

2) cabling from the distribution box to the demod board (one-afternoon kind of job)

  4459   Wed Mar 30 02:55:02 2011 SureshConfigurationElectronicsRF System : Status and Plans

I have prepared several diagrams outlining the current state of the RF System.

These are uploaded into the svn40m here  and will be kept uptodate as we complete various parts of the task.  These plans have taken into account

the new priorities of the LSC (set out by Koji here )

We (Koji, Kiwamu and I) took stock of the RF cables which we have inherited from the earlier RF system and have made new plans for them.

I took stock of the filters purchased for the modifying the demod boards.  We have pretty much everything we need so I will start modifying the boards right away.   The following table summarises the modifications

 

PD freq # of PDs

LP Filter (U5)

  Demod board

Qty available Inline HP filter Qty available
11 MHz 5 SCLF-10.75 7 - -
22 MHz 1 SCLF-21.4 3 - -
33 MHz 2 SCLF-36 3 SHP-25 1
55 MHz 3 SCLF-65 4 SHP-50 2
110 MHz 1 SCLF-135 3 SHP-100 1
165MHz 3 SCLF-190 1 SHP-150 1

We seem to have a spare SHP-175.  I was wondering where that is supposed to go. 

This is the status and tentative schedule for completing the various tasks.  I have put the dates based on priority and state of the hardware.

 

The RF Cable layout plans are drawn on top of a Lab Layout.  The various subsystems are drawn (not to scale) on separate layers.  The graffle files are located here  .  I thought they might come in handy for others as well.

 

 

  13329   Sun Sep 24 20:47:15 2017 ranaUpdateComputer Scripts / ProgramsRF TF Uncertainties

I have made several changes to Craig's script for better pythonism. Its more robust with different libraries and syntaxes and makes a tarball by default (w/o a command line flag). These kinds of general util scripts will be going into a general use folder in the git.ligo.org/40m/ team area so that it can be used throughout the LSC.

I don't think we need/want a coherence calculation, so I have not included it. Usually, we use coherence to estimate the uncertainty, and here we are just plotting it directly from the dist of the sweeps so coherence seems superfluous.

Attachment 1: TFAG4395A_21-09-2017_115547_FourSquare.pdf
TFAG4395A_21-09-2017_115547_FourSquare.pdf
Attachment 2: TFAG4395A_21-09-2017_115547.tgz
  173   Thu Dec 6 15:21:59 2007 albertoFrogsElectronicsRF Transfer Function of Stiff Aluminum Wires
Transfer function of 3cm long Aluminum wires and of 3cm stranded wires
Attachment 1: TF_3cm_stiff_wires.amplitude.png
TF_3cm_stiff_wires.amplitude.png
Attachment 2: DSC_0225compressed.JPG
DSC_0225compressed.JPG
Attachment 3: TF_3cm_stranded_wires.amplitude.png
TF_3cm_stranded_wires.amplitude.png
  6837   Wed Jun 20 01:02:20 2012 JamieUpdateGreen LockingRF amp removed from X arm ALS setup

I very badly forgot to log about this in the crush of surfs.

I removed Koji's proto-beatbox RF comparator amp from the X arm ALS setup.  I was investigating hacking it onto one of the discriminator channels in the new beatbox, now that Yuta/Koji's Yuta/Koji's phase tracker is making the coarse beatbox path obsolete.  Upon further reflection we decided to just go ahead and stuff the beatbox board for the X arm, and use the proto-beatbox to test some faster ECL comparators.  This will be done first thing in the morning.

In the meantime the old amp is in my cymac mess on the far left of the electronics bench.

  11101   Thu Mar 5 11:18:28 2015 manasaUpdateGeneralRF amplifier box

I pulled out the RF amplifier box from the IOO rack and swapped the amplifiers for FOL beat frequency amplification. The earlier gain of 62dB (ZFL500LN + ZFL500LN) was reduced to 40dB gain (ZFL500LN+ZFL2AD).

I also swapped one of the broken sma cables that was connecting the two amplifiers with a good one. Front ports of the module were relabeled and the box was put back on the rack.

During the course of this work, I had to turn OFF the green BBPDs on the PSL table to protect them and they have been powered up after putting the module back.

Quote:

As Koji found one of the spare channels of the ALS/FOL RF amplifier box nonfunctional yesterday, I pulled it out to fix it. I found that one of the sma cables did not conduct.

It was replaced with a new cable from Koji. Also, I rearranged the ports to be consistent across the box, and re-labeled with the gains I observed. 

It has been reinstalled, and the Y frequency counter that is using one of the channels shows a steady beat freq.

I cannot test the amplitude of the green X beat at this time, as Koji is on the PSL table with the PSL shutter closed, and is using the control room spectrum analyzer. However, the dataviewer trace for the fine_phase_out_Hz looks like free swinging cavity motion, so its probably ok.

 

  10964   Mon Feb 2 16:58:56 2015 manasaUpdateGeneralRF amplifier for ALS

Today I was around the IOO rack.

I shutdown the power to the beat PDs on the PSL table and disconnected the D sub 3w3 connector that was powering the RF amplifier panel on the IOO rack.

I moved the RF amplifier from the panel to a box that can go on the rack. The box will also hold the RF amplifiers that will be used for FOL. I have not completed putting in all the amplifiers. But the RF amplifier for ALS is in place and the box has been installed on the IOO rack for locking tonight. The power supply to the green beat PDs has been switched ON.

I took the out of loop noise measurements for ALS X and Y and the attachment is the screenshot of it (X and Y have rms of ~300Hz and ~400Hz).

I had to touch the Y end steering mirrors for green to get maximum GTRY before making thes measurments.

Attachment 1: ALSXY_outLoop.png
ALSXY_outLoop.png
  10970   Tue Feb 3 16:43:48 2015 manasaUpdateGeneralRF amplifier for ALS

I pulled out the RF amplifier box from the IOO rack again and added the new RF amplifiers for FOL. 

I replaced one of the decoupling capacitors of the ALS beat note RF amplifier ; the poloproylene capacitor with a ceramic capacitor (0.1uF) .

After putting back the box, I confirmed that we had a beat note. I did not get a chance to measure the ALS noise after putting back the box because the IFO was already occupied.

I will post a detailed elog of the components in the RF amplifier box once I am done with it (hopefully tomorrow)!

  10977   Wed Feb 4 21:05:24 2015 manasaUpdateGeneralRF amplifier for ALS

The components of the RF amplifier box are in place. The RF amplifier box has been mounted on the IOO rack and the front panel connections have been labeled. Attached is the photo of how things look in the inside for future reference.

Sometime in the next few days the box will be pulled out to replace the panel mount SMA barrels in the front with insulated ones.

Attachment 1: RFampBox.png
RFampBox.png
  11026   Fri Feb 13 19:41:13 2015 ericqUpdateGeneralRF amplifier for ALS

As Koji found one of the spare channels of the ALS/FOL RF amplifier box nonfunctional yesterday, I pulled it out to fix it. I found that one of the sma cables did not conduct.

It was replaced with a new cable from Koji. Also, I rearranged the ports to be consistent across the box, and re-labeled with the gains I observed. 

It has been reinstalled, and the Y frequency counter that is using one of the channels shows a steady beat freq.

I cannot test the amplitude of the green X beat at this time, as Koji is on the PSL table with the PSL shutter closed, and is using the control room spectrum analyzer. However, the dataviewer trace for the fine_phase_out_Hz looks like free swinging cavity motion, so its probably ok.

  11027   Sat Feb 14 00:42:02 2015 KojiUpdateGeneralRF amplifier for ALS

The RF analyzer was returned to the control room. There are two beat notes from X/Y confirmed.

I locked the arms and aligned them with ASS.

When the end greens are locked at TEM00, X/Y beat amplitudes were ~33dBm and ~17dBm. respectively.
I don't judge if they are OK or not, as I don't recall the nominal values.

  4479   Thu Mar 31 20:37:10 2011 AidanSummaryGreen LockingRF amplitude source

 I gutted one of the $2 red laser pointers to build a laser source whose amplitude we could modulate at RF frequencies. Basically, I cut off the bulk of the housing from the pointer and soldered a BNC connection into the two terminals that the 2x 1.5V batteries were connected to. When I applied 3V across this BNC connector the diode still worked. So far so good.

Next I added a bias tee to the input. I put 3V across the DC input of the bias tee and added a -3dBm signal into the RF port of the tee. The laser beam was incident on a PDA100A (bandwidth of 1.7MHz) and, sure enough, Kiwamu and I could see a flat response in the amplitude at a given drive frequency out to around 1.7MHz.

We should check the response on a faster PD to see how fast the laser diode is, but we should be able to use this now to check the RF response of the green beat note PD. 

TO DO:

1. Add some capacitors across the DC input of the bias tee.

2. Do something about the switch on the laser diode.

3. Attach some labels to the laser that specify what is the required DC voltage and the maximum acceptable RF modulation amplitude.

Attachment 1: P1000543.jpg
P1000543.jpg
Attachment 2: P1000544.jpg
P1000544.jpg
Attachment 3: P1000545.jpg
P1000545.jpg
  2059   Tue Oct 6 20:09:50 2009 JenneOmnistructureEnvironmentRF area is clean!

I spent part of the afternoon cleaning up the area next to the Mode Cleaner where we keep all of our RF stuff:  Attenuators, BNC/SMA/LEMO adapters, Mini-Circuits items, and all sorts of other things which are useful while looking at our electronics/RF stuff.

We got another set of "Lyon" drawers, which aided in the organization process....Bob ordered 2, so we now have a 'spare' drawer set if anyone can think of something else to organize (unless this was premeditated for optics or something else?).

As you can see in the picture, (1) it's no longer a total disaster over there, and (2) some of the drawers have sub-divisions to make it faster and easier to find what you're looking for.  Please help out by putting things away in their proper place, and adding more labels or dividers to the drawers if there's something else which needs a 'spot'.

Attachment 1: DSC_0894.JPG
DSC_0894.JPG
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