System modification history

Bottom of page (most recent entry).
 

• 21sep98 hurricane georges.
  
• jan99     Dome lowered about 3 ".
  
• 01feb00        elevation rails reshimmed ao9 survey.
• 11feb00    Pointing model 11 completed and installed.
• 11feb00    turret positions of horns resurveyed by lynn baker. Turret positions updated.
• 07mar00    Started tracking the average height of the platform using the distomats and tiedowns.
• 04sep00    pointing preprocessor installed and activated.
• 23aug00   610 receiver model was updated.

Had been using lbn model. Checked the pointing and it was off by 5 arcminutes (5db loss). see 610 calibration to see how good the model is now.

• xxnov00    430 gregorian dome switched from linear to circular polarization.
• xxdec00    Wheels on dome broke. Replaced them. Support beam (2000 lbs) now on az arm.
• 13jan01    Reflector tieback adjustments below main support cables completed (1st cycle)

2000 points adjusted. This is the first cycle.

• 16mar01 Completed pointing model 12 (but not installed).

Pointing model 12 taken during the day with active tracking of average platform height. Verification of the model didn't look so good. They were some unexplained jumps in the pointing that didn't fit well. Sband used this model for a few observations.

• mar01 ?? Reflector tieback adjustments below main support cables completed (2nd cycle).

The date is a little suspect. For sure it is before 20 apr01 since the remeasurements were done by then.

• 23may01 610 feed changed from skinny to fat dipole feed. (day is approximate).
• 01jul01   Completed reflector panel adjustments (all panels) SE quadrant of dish.
• 25jul01   Completed reflector panel adjustments (all panels) NW quadrant of dish (date??).
• 05jul01   610 model of 23aug00 was not being used by the gui. Gui updated to use model.

The gui was still using the old lbn model. The model from 23aug00 was not being used so users of 610 system via the gui were still 5 arcminutes off (5db down). Updated the gui to use the correct model today.

• 31jul01   tertiary motors installed.
• 01aug01  theodolite survey. Tertiary and dome paddle locations.
• 04aug01  tilt sensor run all az,za to meausure pitch,roll.
• 09aug01  theodolite survey of dome from ao9.
• 10aug01  angle of teflon pads on tertiary adjusted so pads are parallel to rubbing blocks.
• 15aug01  panel adjustments for northwest quadrant of dish completed.
• 19aug01  14:00 ast. updated dut1 (utc-ut1). Was off by  -.125 seconds of time .
• 01sep01   updated sbw hcorcal on 04apr02 retroactive to this date.
• 16nov01  lband wide filter bank filter #6 (1360-1470) were removed. The filters were bad (not sure for how long they had been bad.
• 15dec01   sbn. updated gain(az,za) in idl/data for gainget() routine. uses sep01->nov01 observations after dish adjustements.
• 19dec01   xband receiver installed.
• 27dec01  heating resistor installed on xband waveguide for condensation.
• 06feb02    xband horn moved up .44 inches. turret position 161.99->162.34, model updated 15.asecs (from horn survey 05feb02). Then switch xband model to model 13a (jan02).
• 27feb02    dome weighed using load cells and jacks.
  
• 04mar02    bill sisk adjusted mindex on the tertiary. It has moved to the edge of the window.
• 20mar02    switch new ac in dome fixed.Both ac now on. old:19C, new 22 C
• 29mar02 surveyed sbh,xb,sbn.. sbh needs to move 1.068 in y, xband -1.131 in y
• 31mar02 surveyed the tertiary. z error -.2747 inches.
• 31ma02   sbh moved turret position 125 to 124.150 from horn survey (sidelobes then looked bad).
• 02apr02   xband. moved turret position 162.34->161.50 and updated model offset. From 29mar02 survey
• 02apr02   sbh. turret pos 124.15->125.75 (from turret swings).
• 03apr02   sbh. turret pos 125.75->125.827 got survey sign correct. SBH az offset +21 -3.45 from 02apr02 pnt check and move of turret position.
• 04apr02    sbw. added new calvalue for hcorcal. Data from sep01. backdata active date to 01sep01. The diodes had been replaced prior to this.
• 09jul02    15:00 hydraulic brake on dome now active.
• 20jul02      327 installed new rcvr ..room temp amps...
• 01aug02    around jul02,aug02 felipe tightend the small rollers for the dome on the right side. Play is now about 1/32 inch.
• 15aug02    327 rcvr pointing model updated offset az,za +3,+130" fromcalib runs 07aug02
• 15aug02    610 rcvr. filter retuned to 609.5 Mhz 4Mhz Bw. updated calib config, tsysconfig, ifsetup.proc.
• 21aug02    lbn horn focus moved down 3.84 inches to correct for wrong phase center.
• 28aug02    cb horn focus moved down 1.08 inches to correct for wrong phase center.
• 30aug02    610 antenna switched from fat dipolse back to skinny dipole.
• 04sep02    outside rollers on elevation rail for dome moved in 1/4" to tighten up play as dome moves up/downhill.
• 05sep02    sband high shutter installed.
• 10sep02    new lbn gain curves using data 21aug02->9sep02.  Za only fit. Good from 21aug02 when horn was moved.
• 15sep02    az encoder on ch side broke, was replaced.
• 16sep02    az encoder dome side jumped (maybe when ch side broke). added -1446 to sinza az term for all models except ch (see 25sep02)
• 17sep02    sbn receiver down for repairs. lbn,xb dewar temps decrease (sbn is on same compressor).
• 18sep02    1st new whiffltree installed on dome. Looking uphill it was downhill, right side.
• 21sep02    updated dut1. went from -302 Ms to -232 Ms (correct) so pointing changed by 70 ms.
• 25sep02    updated carriage house model for az encoder jump that occured on 16sep02.
• 26sep02    upstairs pwrmeter broke.
swapped upstairs,downstairs pwrmeters. downstairs using just polB to adjustlevels till new meter shows up (probably) on 30sep02).
• 04nov02    left downhill dome trolley replaced with new one.
• 19nov02    new dome trolley installed. looking uphill 2nd on the right from the bottom
• 20nov02    new dome trolley installed. looking uphill 2nd on the left from the bottom
• 21nov02    refocused lband wide feed.
• 25nov02    100 Mhz for system found unlocked at 17:45 .This locks everything upstairs. Was jumping by about 200 hz at 12Ghz every 15 seconds.   Seti people noticed it during a test. The pll module that converted from 5 Mhz maser to 100Mhz was out of lock. Fixed 28nov02 17:00. Was locked on 22nov02 for the vlibi run. After that we're not sure.
• 9dec02    5th trolley installed (need to check this out..)
• 16dec02    5th trolley removed for adjustments.
• 24dec02    5th trolley reinstalled.  (3rd left)
• 08jan03    6th trolley installed right 4th uphill. 123 left,124 right
• 15jan03    7th trolley installed  right uphill 3rd position. 123 left, 1234 right.
• 06feb03    lbw receiver removed from turret floor (placed on tertiary platform) about 400 lbs.
• 08feb03    felipe finished first shimming of the elevation rails.
• 09feb03    tried to straighten the azimuth arm "bend" by pulling on the arm....(bend was not really there).
• 10feb03    pnt vme crate power supply expires. on replacement fiber for irig to platform broke. pnt started running on its internal clock (on the irig board). By 16feb03 it had drifted off by about 1.5 seconds.
• 12feb03    survey dome from ao9. 2 za strips, 1 az swing.
• 13feb03    felipe "touched up" the shims on the elevation rails during the day.
• 15feb03    more shimming of elevation rails
• 16feb03    18:00. irig fiber to platform fixed. Pnting was running on local clock. It was 1.5 seconds ahead when it was fixed. It was probably broken 10feb03 when the pnt vme crate power supply was changed and the fiber got bumped.
• 17feb03    lbw dewar (about 400lbs) on tertiary platform lowered to ground. New lbw receiver lifted and installed in rotary floor
• 21feb03    zeeman box removed from iflo upstairs.
• 25feb03    shimming of elevation rails completed. tugging of shim pack horizontally also done.
• 28feb03    added weight (water) to platform. T12:2400,T4:2400, T8:1400 to compensate for T8 hairpin replacement
• 27feb03    dome lifted about 1.65 inches.
• 01mar03    model14 started. They still have dome bolts to replace on the dome side. but shimming and dome motion is done.
• 04mar03    model14 installed with old feed offsets
• 07mar03    18:00 new offsets for model 14 installed.
• 10mar03     17:00. offsets of 07mar03 were entered backwards.. corrected here.
• 31mar03    lbw new calvalues installed (measured 06mar03, back dated to 17feb03).
• 22apr03    new cal diodes installed on cband rcvr.
• 23apr03    downstairs iflo polA sbc1 monitor port isolation improved with another amplifier.
• 05may03    seti IF cabinet removed from turret floor. 450 lbs.
• 05may03    loose cable in cband cal box tightened. (or maybe it was 06may03)
• 13may03    lbw. switched order of postamps. before: 24dbGain,filterBand,10dbGain. after 10dbGain,filterbank, 24dbgain. thought 24dbgain amp causing long compression.
• xxmay03    1320Mhz hipass filter lbw moved from outside filter bank to inside filter bank. Date is aprrox. The filter was installed with the polarizations reversed. It was fixedon 16mar04.
• 14may03  installed remeasured calvalues for sbh. back dated to 01mar03.
• 16may03  measured cal values cband using sky and absorber (cal cable tightened on 6may03)
• 18may03  installed cband cal values 22apr03 to 4may03 and 05may03 to ..
• 30may03  recomputed xband cals using correct definition of corcal,uncorcal,0cal,90cal..
• 01jun03    3 filters in cor chassis replaced/repaired: 1b,4a different filters, 4b repaired filter from 1b. Eddy ordered 8 new filters to replace them (they were shorting out and causing the instabilities that people had been seeing in the correlator bandpasses for the last few months..
• 09jul03:    ao9 survey of dome.
• 11jun03    (check date).. bill replaced power supply for power counters in interim correlator.
• 14jun03    idl lbw cals. date reversed in file (48 2003 instead of 2003 48). people using idl 31mar03->13jun03 would get the latest cals even if there data was before this (since year 48 is alway before the current date). Fixed on this day.
• 14jun03    lbw gain curve. The gain curve of nov21 2002 after horn moved did  not have the date field (!2003 dayno). People were getting the gain curve from before the horn move. The file had been edited on 17feb03 so it may have been removed at that time. Fixed the problem today.
• 18jun03    wapp pulsar observing . polarization mode , 3level, bw<=50Mhz bug was fixed today. Prior to this, only polA crosscorrelations were being recorded.
• 26jun03    interim correlator. All 8 lowpass filters (before digitizers) were replaced with new filters (see 01jun03).
• 27jun03    interim correlator. amp 4b in 250->baseband chassis replaced. It was oscillating.
• 16jul03    ri digitizer Q1 was occasionally losing the rdFifo pulse. The pulse len was lengthed on this date and the problem appears to have gone away. This problem was seen in data as far back as feb02.
• 20jul03    installed new xband cal values. measured using sky and absorber. backdated to 01jan03.
• 21jul03    xb updated pointing offsets from calibration runs.
• 28jul03    lightning tiedowns. td8: dac blown out. Drove all the way up, limit switch did not turn it off. replaced dac board, checked limit switch. Td4: encoder board bad reading 24 inches. replaced board. Position of td moved by about .8 inches from when it went off. Someone must have moved it when board was off. Since abs encoder ok, position is probably ok.
• 04aug03 updated dut1 for pointing. was about 100 millsecs off.
• 05aug03    05,06,07.. moved all the limit switches on tiedowns. (more info)
• 15aug03    (approximate date). re enforcement for t8 corner where main cable cut was installed.  started mods. Added new stuff, removed lead to keep weight the same until 03sep03.
• 28aug03    vlba filter 1250-1750 in downstairs iflo replaced.
• 3aug03    xband default mixer switched from 10ghz upconverter to 2_12ghz mixer
• 30aug03    polA downstairs iflo 5volts was shorting out when monitor port sbc1 was touched. The semi rigid cable inside box had fallen down and was shorting against vcc of one of the switches inside. This line had been installed 23apr03. This problem may have been occurring for awhile.
• 30apr03    power dip 8am. looks like 11.5 Ghz lo used to downconvert from 10ghz to 1.5 ghz lost lock. Problem remained for 23apr03, 24apr03 daytime.
• 03sep03    last part of T8 reinforcement added 335 lbs extra in T8 corner.
• 04sep03    new xband horn installed.
• 04sep03    xband cal cables "cleaned". cal values no longer valid. need to be remeasured.
• 05oct03    xband rcvr up to test range, cals tsys measured on sky/load
• 10oct03    installed new sbw cal values. backdated to 15aug03.
• 14oct03    8:02 am gregAz encoder jumped by 3 teeth (1.66Amin little circle). Someone probably bumped it. Fixed the problem 16oct03 14:30.
• 14oct03    sbn turnstile stubs switched. Also reversed the rf cables from dewar. The oc pol now uses the better amplifier. cals values in tables also switched.
• 27oct03    new xband cal values installed. back dated to 05oct03
• dec03      Isolation of if2 buffer amplifier outputs increased via more amps/pads. Now the same as sb1a output.
• 07jan04    lbn receiver removed from dome.
• 07jan04    327 recevier moved from turret=21.5 to turret (about) 342.5
• 08jan04    xband receiver moved to new position (close to 310)
• 14jan04    610 receiver moved to new position
• 14jan04    laser ranging pc replaced with a new computer.
• 14jan04    turret floor weighed. did not include lbn or 6to8Ghz receiver.
• 14jan04    turret floor framing reinforced (part that holds the rollers).
• 14jan04-20jan04 . 327 receiver was removed and then re-installed when the turret floor was weighed.The cables from the dewar were accidently left disconnected. They were re-installed 21jan04 2am ast.
• 21jan04      PolB lbw has been having glitches every 2.8 seconds. They are negative going in the bandpass. They are coming from the dewar monitoring circuitry affecting the bias voltage when the 70K dewar temp is read. The 70K dewar temp read was disable 21jan04 12:00 ast so the glitches should no longer be present.
• 26jan04    leaf springs on dome changed out for stronger springs.(date may be off by a week)..
• 27jan04    laser ranging pc moved to different network switch. Archive file moved to observer.
• 28jan04    downstairs IF 720 to 780 Mhz filters installed.
• 09feb04-08mar04 . vertex monitoring, tiedown monitoring were not logging to disc.
• 10feb04    6 to 8 Ghz receiver installed on turret floor.
• 10feb04    rfpwr3 volts to watts conversion math9.c 723.c sband transmitter recalibrated.
• 11feb04    horn survey (1st) all horns by lynn baker.
• 13feb04    cbh horn moved for focus correction.
• 13feb04    shigh horn moved down .8 inches to bring into focus.
• 13feb04    shi new cal diodes installed.
• 14feb04    horn survey after turret positions updated, cbh moved.
• 29feb04    updated cband high model offsets using feb04 calib runs.
• 01mar04    replaced distomat 5 (this was the last old distomat).
• 15mar04    xb rcvr reinstalled. had been on hill. new cals, rfamps. fixed some loose cables in dewar.
• 16mar04  1320 hipass filter was installed with polA,polB reversed. It was corrected today.
• 05apr04    xb receiver reinstalled. came down 29mar04 to work on dewar temp monitor circuit.
• 08apr04    turret floor reenforcing for alfa, kevlar cables installed,tensioned
• 09apr04    resurveyed tertiary into position using theodolite (alfa not yet in).
• 19apr04    (about). 3 new compressors raised to dome for alfa. placed in new forward position on top of dome. about 1000 lbs.
• 21apr04    alfa installed
• 23apr04    lbw polB calval jumps.
• 28apr04    horn survey, turret position updated for alfa.
• 29apr04    horns moved: xb,cbh,cb,sbh,sbw(x). sbn,sbtx,lbw,alfa not moved.
• 01may04    tertiary survey. updated tertiary origin.
• 02may04    horn survey after receivers moved. Lynn had been using an "old" secondary reference set for the last couple of surveys. Today he switched back to the most recent. This caused a jump in y of about .4 inches. The horn positioning above was done with the "old" reference.
• 05may04    low pass filters installed in alfa iflo box.
• 06may04    alfa cover breaks on turret encoder mount. lost encoder position. encoder remounted with a 85.47 deg offset. inserted this in the little star program. tracked two sources to get the turret encoder position close.
• 07may04    lbw had 56 asec error in za. Probably from when the tertiary was moved and we did not move lbw. In lbw  model, i  subtracted -56 asecs from za constant term.
• 08may04    resurvey some horns to get correct turret encoder offset.
• 14may04 sbw cal diodes replaced
• 14may04 sbw focus motion done.
• 17may04 pointing model 15 completed (after verify run).
• 26may04  About 2:30 ast.. on generator, trouble with power (60hz->57 hz). systems rebooting many times.
• 27may04  station clock jumped forward one second. Saw the jump 10 seconds after midnite. Probably occured at midnite. Reset the clock back at 8:24:30 ast. May have been the leap sec flag set in track clock from the power resets of the previous nite.
• 31may04    cband cal polA jumped . Tsys polA went from 31 to about 48 K (jumped back 04jul04)
• 04jul04    cband polA jumped back. TsysPolA went about 48 to 31. This occured after the dewar was warmed up and then cooled back down. Problem must have been in the dewar. Note.. continued jumping till 23sep04 when broken cable polA was replaced
• 12jul04    motion failure azimuth axis. Caused by loose/broken coupling on azimuth encoder. Replaced the encoder and coupling. This is the encoder that is used for positioning the azimuth arm (the encoder on the ch side is the spare).
• 12aug04    ast 2:01:04 jpl hydrogen maser stopped working. Off by 10 millisecs. 10:48:00 ast New maser installed.
• 29aug04    galfa spectrometer installed.
• 08sep04    Rf to If board alfa pixel 0b replaced. Had been an oscillation causing intermod near 1380 Mhz.
• 10sep04    new  sbw gain curve,installed 10sep04. backdated to be valid starting15may04 (new cals installed).
• 12sep04    lbw cals measured 06aug04, installed 12sep04, backdated to 04jun04..
• 09oct04   cband polA Tsys had been jumping around since may04. Beginning of oct04 dewar brought down and repaired. there was a short in one of the wires for polA inside the dewar.
• 18nov04    sbn transmitter experiment. Transmitter run but alfa was not covered.
• 23nov04    sbn 3db pad moved from after postamp to before postamp. Put circulator after postamp. This was to fix the out of band problems when a low side lo was used to mix 2380 to 750 Mhz. There had been lots of junk at around 800-1000 Mhz. It was coming from the lousy match between the rf bandpass filter and the postamp that followed it.
• 10dev04    updated epvchebs file (/share/obs4/dt/dfiles/..) . old file was 1996 thru 2004. new file is 2004 thru 2023. This holds the daily fits the the jpl ephemeris that is used for the earth position info when computing doppler shifts.
• 15dec04 18:45 az encoder 1 (dome side used for az pointing) failed. Encoder was replaced.
• 27dec04  cbh: model offsets az,za incremented by (-.28,-3.8) . data from x102 runs.
• 27dec04  60 mhz birdie. identified as sbwide postamp chassis,cal injection board. Some unused hi speed chips were oscillating.
• 30dec04: filters installed ch to get rid of tv station intermods.
• 17jan05  recalibrated load cells for tiedowns. replaced filter td4-ldcell1 (top)
• 20jan05 azimuth would only go toward - az while in prgtrack mode. preset, rate worked ok. Replaced lcu,plc. Started to work ok. Found that the azencoder offset had been set to 1 degree (since at least 06jun04). With the offset now at 1, the az again trys to go to minus azimuth (exclusively). I reset the offset to 0 and then it worked ok. I also checked and on 19jan05, az=270, with offset=1. the  azencoder was the same as 20jan05,az=270, offset=0. So the software in the old lcu or plc was ignoring the offset. The newer version is not? Another guess is that the program track code in the plc is using the encoder position before the offset is added for the pid loop. I saw that a positive offset caused the az to only move to neg az, while a negative offset would cause the az to only move to positive az (for pt mode only).
• 27jan05: filter installed 430 Mhz system to get rid of tv station intermods.
• 1feb05 : Noise injection boards for receivers.. all replaced to get rid of 60Mhz birdie.
• 23feb05: (date not certain). lbw filter bank. 1370 hipass polB hand a misthreaded n/sma connector, replaced. Also 1360-1470 bandpss pola had a loosed sma connector .. tightened it.
• 03mar05: lbw filterbank 1360-1470 filters. switched filters polA->polB polB->polA to see if instabilities around 1390 change or the power dropouts.
• 04feb05: dome cam limit switches replaced with strikers and regular switches when the cam switch broke.
• 25feb05: td 4 jack breaks. looks busted ball bearing.  replaced jack 28feb05. reset encoder, limit switches.
• 16mar05: model16 carriage house installed.
• 17mar05: td12 jack replaced (maintenance).
• 24mar05: alfa Rf to If converter pixel 0b replaced to get rid of wandering birdie around 1430 Mhz.
• 29mar05: alfa rf to if convert pix0b spare. had been installed without cover over chips. installed cover today.
• 05apr05: alfa pixel 2a,b 10db amp added before the mixer upstairs to test oh performance.
• 08apr05: 10db amp installed in front of 1st mixer/filterbank for all alfa pixels.
• 12apr05: 6db pads installed before the new 10db amps in alfa.
• 23apr05: wapp pulsar data archive started.
• 25apr05: alfa filter bank modified. 10db amps are now only on the 1665 filters. the wideband filters are back to the way they were before any of the filter bank changes.
• ??may05 : fans added to polA distribution amp downstairs. (this may have caused the galfa cable switch).
• 25may05: cband receiver reinstalled. New amps installed, new cal values.
• 31may05  galfa pixel 4a and 6a (count from 0) were switched at the output of the distribution amps downstairs. They have been switched since at least 3may05. They were not switched on 12dec04. At 11am ast this problem was corrected.
• 01jun05: lbw warmed up dewar. found loose/broken cable polA probe. also found that cal cable polB in dewar was cracked. (need to verify that these were the correctpols since the banging caused polB to jump the most, not polA
• 09jun05: wapp4 has its kernel upgraded from 2.4.18 to 2.4.31.
• 10jun05: switches on dome wheels checking for failure enabled. lights in control room. don't know if they are connected to the emg stop circuit or not.
• 15jul05: wapps 1,2,3 have there kernel upgraded from 2.4.15? to 2.4.31
• 21jun05: lbw installed new cal values. backdated to 01jun05. (bug in d1->polB hi.. fixed 09aug05).
• 21jul05: diode 1 for lbw died. 22jul05 Switched the software so no matter what people ask for they'll get diode 2. Will take about 8 weeks to get some new diodes.
• 30jul05: installed new cal values for cband (amps/diodes installed 25may05). The values for hcorcal polB look a little off.
• 03-04aug05: installed beams in feed tower to brace some beams that are deflecting (probably caused by the kevlar cables).
• 08aug05: cband cals now correct (fixed bug in hcorcal/hxcal polB).
• 09aug05: lbw cals .. fixed bug d1->polB high (first installed 21jun05).
• 18aug05: sbw cal cables changed. This modified the cal value injected into the dewar
• 29sep05: updated cal values for 430ch (measured 27sep05).
• 30sep05: 0am till about 8:30 am (ast) station clock behind real time by 1 second. leap second inadvertantly added to the station clock. Pointing off by 1 sec of time (pointing at a lower ra) .
• 11nov05: azimuth encoder problems enc1 and 2. on 14nov05 lost encoder 1. realigned pointing with the index. 16nov05 replaced both encoders.
• 23nov05: lbw new cal diodes installed.
• 28nov05: lbw new cal diode values installed.
• xxdec05: 1440 filter bank installed in alfa. xx gt 1
• 04dec05:  lbw polB cal value jumped 20%. jump started on 04dec05, done by 05dec05.
• 23dec05: 430 yagi moved down .41 meters. Now 3 meters below paraxial surface
• 10jan06: air conditioner in rfi shack changed (old one was not working).
• 11jan06: put fan in distomat 6 (i could be off by a few days on the date).
• 26jan06: 3rd ac installed in dome. 2 compressors are outside at entry to dome . 1 compressor still on service platform. The old ac is switched off. no longer needed.
• 23feb06: lbw cal values remeasured. installed on 28feb06 and backdated to 04dec05 when polB cal jumped.
• 03apr06: aeron cpu, and 4 wapps. Removed cpu intensive jobs being run every mornging at 4am by cron.daily (slocate.cron, etc). Should help ntp time resets.
• 10apr06: sbn cals. Installed new values. backdated to 14oct03. Need to reprocess old calibration data.
• 23may06: 430 yagi, found broken capacitor for 1 of the driving elements. Ganesh remeasured the cal values (they were way off).
• 25may06: cband cal polA sma connector was loose. Tsys had been wandering because of this.
• 25may06: 430 dome cal driver upstairs. Power supply had failed. replaced it.
• 16jun06: lbw dewar warmed up and opened. found loose sma feed thru in dewar for polB cal. Probably causing the drifts in polB Tsys.
• 02aug06: new az2 encoder installed. create 614 khz comb in 430,327.
• 28aug06: installed new cal values for cband (measured back in 06jul06).
• 31aug06: installed new cal values for lbw (measured on 06jul06). The cal change occurred on 16jun06 when the dewar was warmed up and a loose cal cable was found.
• 29sep06: removed final skybolt ap (ap#2) from the da vme crate. Speeds up the reboot a lot. The ap was probably still good (although it was no longer used).
• 05oct06: new az2 encoder replaced with old az encoder (around1pm) to get rid of 614 khz comb in 327/430. It has been there since 02aug06 (more info)
• 14oct06: az 1 encoder reading failed. Telescope switched to use az2enc on ch side. This created a pointing error.
• 18oct06: 18:00. replaced az 1 encoder. realigned with index pointer. Still bad. Found encoder board port 1 bad. Moved az1 encoder to encoder port 2 to get rid of pointing error introduced by 14oct06 change.
• 26oct06: put repaired encoder board back in . Az 1 encoder now working.not longer plugged into port 2. Got rid of az encoder offset in lcu display (was 1 degree).
• 27oct06: foundloose cable 750 mixer chassis polb. It was probably  causing jumps in polB iflo.
• 30oct06: replaced if attenuator polB upstairs. Failed 28oct06. Was giving 22 db  atten all the time. May have been causing problems with polB if it was intermittantly failing before this.
• 14nov06: az encoder 1 failed. Had to replace it. Required a realignment with the index.
• 14nov06: tiedown 12 loadcell 1 replaced with spare. It had been  about 25 ohms off at the loadcell.
• 27nov06: tertiary huffman box mounted on outside porch of turret room brought down. weight:150 lbs.
• 28nov06: 3 cables removed from the catwalk tray: old sband control cable,old telephone cable, and unused worn power cable. Total weight removed: 1643 lbs.
• 5dec06:  05dec06 to 07dec06 removed 2115 lbs. Mainly from bottom center of azimuth arm. Will be brought back up after painting project. 245 lbs removed from the feed tower.
• 11dec06: updated ut1-utc . Also updated the models for 1az term and az*sin(za)
• 15feb07: crval1 bug in fits header fixed. Bug could have header freq off by many Mhz. See cima page, cima fits log.
• 07mar07: bad cable found in wapp4 brd1 polB (alfa beam6B). Fixed on 07mar07. It had been bad during feb07.
• 31mar07: laser shack removed from corner 4 (about 1600 lbs) .
• 03apr07: lead from corner 4 removed. (5300 lbs) .
• 03apr07: lbw brought back up to the dome. screws omt tightened hopefully getting rid of the 1400Mhz resonance.
• 04apr07: greg dome local disable cable breaks in dome cable drape then bothazimuth encoders reset .
• 13apr07: xband receiver brought down for maintenance.
• 14apr07: weather station fails. brought down for maintenance.
• 17apr07: alfa lowered from dome to electronics lab for maintenance.
• 18apr07: vertical sides for painting containment installed corner 12.
• 19apr07: vertical sides for painting containment installed corner 8.
• 20apr07: weather station weather vane removed. Was in the way of the painting. Will reposition it to another spot.
• 25apr07: stopped observing .. start of painting shutdown.
• 30apr07: stopped monitoring dewar temperatures (since no dewars.)
• 04may07: looks like corner 12 containment sealed. Temp sensor (inside containment > 110 degrees)
• 03dec07: start recommissioning telescope after painting project.
  
• 09dec07: moved nuts on td 4 and 8 to equalize td extension.
• 10dec07: alfa lifted and reinstalled
  
• 13dec07: started pointing model (data thru 16de07). 5 compressors installed
• 16dec07: finished pointing model
• 16dec07:evening started model verify.
• 04jan08: lifted 6th compressor to dome
• 09jan08: installed waveguide cable car landing to center bearing (about 5000 lbs).
• 14jan08: lbw pointing. updated after verify run. offsets were 4.44 az,  -2.68za  asecs
• 05feb08:readjusted the pots for azimuth motor amplifiers so they are at standard setting.
• 16apr08: increased alfa beam 0b gain by 3db at downstairs if amp
• 16apr08: 500 lbs placed on ch end of azimuth arm . They put the work platform back.
  
• 17apr08: found loose cable downstairs synth1 used for mixer lo's. At 1000Mhz output 10dbm at 1010 output 2dbm. Cable was loose and the pin was short. Also found synth3 cable loose (but pin was ok length).
• 13jun08: new cooled 327 receiver installed with new cal values
• 08jun08: lbw cryo failures. About 4 warmups.
  
• 21jun08: updated pointing model using 1az,3az fits to the pointing data.
• 01jul08: subtracted 4asecs from xband za constant term for bania. no other models were changed.
• 15aug08: 800 Mhz rfi feed installed in place of 610 feed.
  
• 29aug08: lbw cals measured before warmup. Installed backdated to 30apr08.
  
• 05sep08: lbw warmed up, bias voltage bulkhead cable replaced.
• 19sep08: finished modifying alfa bias voltages for amp 3 for long recovery times.
• 10oct08,20oct08: laser ranging reflectors replaced.
• 08jan09: td12 jack replaced.
• 01jul09: oplog az encoder off by 1 tooth??
• 02jul09: az 1 encoder replaced
• 15sep09: alfa down to be worked on
• 19sep09: td12 load cell broke. replaced 06oct09
  
• 30oct09: alfa reinstalled
• 03feb10: Found broken beam platform where  td12 backstay ties to platform (left side looking from north). Not sure when it broke.
• 24mar10: repair on broken beam completed. still limited to 3.5 to 12 deg  za
• 14sep10 : started repairing u2-u2l3 by adding c channels.
• xxsep10: lbw window blown out. brought down to lab and fixed.
  
• 30sep10: alfa thermally cycled.
• 19oct10: alfa motor replaced.
• 21oct10: recompiled agcProg, tdtrk, pntProg to have new software limits: 1.06 to 16 za.Probably won't install until 22oct10 daytime.
• 01nov10: cband gortex horn comes loose. tsys goes up. fixed 17nov10.
• 05feb11: finished  reinforcing the telescope.
• 08feb11: changed za limits back to 19.69 (from 16).
• 14mar11: 800 rcv pointing model offsets updated (after mount bolt tightening).
• 22jun11 : interim correlator sbc3,4 Tsys increase from +5volt pwrsup failure of halfbandfilter 3,4 chassis.
• 22jun11: if2 rack polB +5 volts power supply failure.
• 26jul11: alfa brought down to lab to work on it.
• 06sep11: alfa reinstalled
• 27feb12: thru 04mar12: pointing model 18 data taken (with new td position).
  
• 09mar12:alfa brought  down to the lab.
  
• 20apr12: alfa  reinstalled
• 05jun12: model18A installed. now using new td positions.]
• 12aug12: lbw new cal values installed.
• 16aug12: xband new cal values installed.
  
• 19sep12: cbh new cal values installed.
  
• 27sep12: cband: new cal values installed
  
• 19oct12: 430 dome jennings relay polB removed. Little power was getting through the relay.
• 28oct12: new sbn receiver installed
• 31oct12: horn survey sbn , sbtx receivers
• 31oct12: lbw 1370 hipass filter switches were causing ripples. switches replaced.
  
• 02nov12: horn survey all other receivers.
  
• 09nov12: sbn circulator postamp chassis had been installed reversed. fixed.
• 18nov12: lbw pressure relief valve blew out. Tsys problems lbw started after this.
  
• 20nov12: sbn new cal values  installed
• 26nov12: sbn moved up in z direction to put it in focus.
• 04dec12: lbw dewar brought down to lab to work on it.
• 07dec12: lbw dewar reinstalled in dome.
• 01apr13: punta borinquen carsr radar starts testing.
  
• 29apr13: punta borinquen carsr radar now blanking in ao direction
• xxjul13 : sometime in jul13, punta borinquen carsr radar stoppped blanking in our direction.
  
• xxjul13: faa carsr radar being brought online.
  
• 12jul13: dome  drag link comes loose
• 25jul13: ao19  cooled receiver tested on telescope.
• 01aug13: sbn first stage of amps burned up when shuter bypassed.
• 05aug13: turnstile junction 430 receiver damaged when ao19 removed.
• 08aug13: faa carsr radar starts broadcasting.
  
• 17sep13: 430dome polA  bandpass filter reinstalled. fixed solder joints, teflon connecteors
  
• 04oct13: punta borinquen carsr radar blanking toward ao (again) (more info)
  
• 28oct13: faa radar starts blanking in ao direction (more info)
• 13jan14: 6.4 mag earthquake damages cable m8-4 (more info)
• 11mar14: earthquake repair finished.
  
• 28mar14: alfa down to lab
• 21may14: alfa reinstalled
• 25nov14-09nov14 - scramnet observer cpu not forwarding packets to cor,da crates (more info)
• 11mar15: alfa down to the lab
• xxjul14  : sbn amp replacement.the old sbh hi amp that was installed 01aug13 was replaced by a new chalmers amplifier. polB in dewar, polA outside
  
• 26mar15: hf mesh first raised. not hangking at final height
• 28apr15: alfa back up to the dome.
• 16sep15: site power. 750KVA transformers. changed taps on output (by 2) to increase site voltage.
• 10jan16:  az 1 encoder fails. replaced.
  
• 16feb16: observing stops.. platform painting. alfa down to the lab
• 21apr16: platform painting done..
• 04may16: first fringes 12m, 305m
  
• 13may16: alfa backup to platform. beam 0a has problems..
• 18may16: new visitor center exhibits are now on during the day for visitors.
• 24may16: ch cals hardwired to 192,122 K.. attenuator was not working..
• 02oct16: az encoder 1 fails. replaced.
• 10jul17 :  sband heat exchangers remove from platform
• 04aug17:   new sband heat exchangers installed on platform.
• 25aug17: td4 jack replaced (more info)
• 20sep17: hurricane maria. line feed falls into dish
• 27oct17: 1400 lbs ballast added end of az arm to compensate for  missing line feed.
• 13nov17;  caltype selector fails. always corcal. fixed 5dec17
• 01dec17: model19A installed
• 09dec17: commercial  power returns to ao.
• 15apr18: 3 trolleys from the dome cable  drape were pulled off of their beam.
•  ran through the night with the trolleys hanging upside down.
• one of dome motor cables was damaged.
  
• 26-30may18: arcing from site power phase A. At the power pole by the airglow lab (.ps) (.pdf)
• 180731: sband synth (upstairs) fails. Also caused trouble since 10Mhz for 1st LO synth getting 10Mhz from sband synth output.Not sure how long it was bad. Pulsar observers had seen freq jumps for many months??
• 180824 : 2nd lo synth #3 was 12db low in output power at 2160 Mhz. at 1000 Mhz it was ok.. Not sure how long this was bad. replaced 180824.
• 181230 maser fails. 14:30 utc started to fail. 18:20utc out of lock
• 181231 rubidium clock replaces maser 19:05 UTC.
• 190116: dust collector removed from platform (2130 lbs)
• 191127: sbn switched the stubs on the sbn omt, to reverse polA,polB on the output of the dewar (more info)
  
• now: rhcp comes out on dewar chb, and lhcp comes out on dewar cha (the tx transmits rchp)
• there was always another
  
• 200228  td4 jack fails. left jacks in place till new one up and arunning on 03mar20. pos had td12 at 10"
• 200229  if2 synths fail after power dip. fixed freq till 200301 19:30 (only x102 lost).
• 200603 if2 synth 4  fails after power dip.  16:45 03jun20 till 8:00 08jun20  freq fixed at 550Mhz.
• 200810 auxmain4North fails.
• 220918 hurricane fiona.
  
• 220927 station clock was rubidium . saw 3ms jump vs utc (gps ant providing 1sec tick had come down after fiona. switched to maser 14:50
  

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