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GBT Operations & Commissioning Meeting

18 August 2006

AGENDA

• Az Track, Antennae Report -- Bob
• Observing News -- Ron
• Scheduling Status -- Carl
• Microwave Electronics Status -- Roger
  • Operations
  • Development
• Digital Electronics Status -- Randy
• Software Status -- Mark
• Pulsar Related -- Scott
• MIT/LL 43m Project -- Glen
• Any other Business

Az Track, Antennae Report -- Bob

• • We received 7 new splice plates this week. These were purchased to allow work to begin on setting the first baseplates while the others are refurbished.
  • The material for the bolts will be poured and rolled the first week in September.
  • We continue with miscellaneous purchases before year end.
  • We will have another surveying activity Monday night during general test time, and continuing into the maintenance period on Tuesday.

• • The structural inspection is going well, and should finish up as scheduled if the weather continues to be nice.
  • The material for the spring plates for the 140' has arrived at the fabricator's shop for machining.

Observing News -- Ron

We supported 14 projects in 24 sessions, including a VLBI run. Average setup time was 13 minutes. The telescope was also scheduled for 42 hrs maintenance, 5 hrs PTCS tests, 1 hr program checkout, and 2 hrs calibration. Lost time was 2.6 hrs, about 2.2% of the time scheduled for tests and observing. Of the 14 operator shifts, only 4 had lost-time problems. Problems were:

• Computing (2 instances, Titania and Wind) : 1.48 hrs
• Spectrometer : 0.5 hrs
• Spigot : 0.4 hrs
• Astrid (3 instances) 0.25 hrs
• No-lost-time problems : Active Surface, Spec Proc, SDFITS, Ku-Band cryo, GBTIDL.

In other news, we decided on our support schedule for September.

Scheduling Status -- Carl

Microwave Electronics Status -- Roger

Operations

No issues this week.

Development

Q-band Receiver: Q-Band receiver assembly continues. Except for the new mixer bias assemblies, the mechanical part of the IF rebuild is complete. A large part of the week has been set aside to investigate whether voltage transients have been destroying Q-Band amplifiers. Transients were found due to starting and stopping the refrigerator motor, and we are investigating ways of reducing or eliminating the voltage transients. We are preparing to measure the conversion loss of the mixers that have been installed in the Q-Band receiver.

Ka Receiver: The MMIC LO doublers and dual chip amplifiers were tested and found to have short circuits due to conductive epoxy squeezing into the DC feedthroughs. After cleaning and retesting we have three working doublers, one working amp and one amp missing a coax to microstrip tab but working. One amp lost a chip due to the epoxy shorts, both amps requiring further micro attention are being repaired Friday (18th). Work on the 300K stage continues but slowed due to my attention to the doublers and amplifiers. A good portion of the wiring harness from the previous assembly is usable, saving some time in the wiring process, which shall begin in earnest this (Thursday, 17th) afternoon. Gate leakage currents were checked on the cryogenic amps and they seem to be OK - no different than when constructed in 2004.

C-band: The new cryostat was assembled and successfully vacuum leak-checked. The cylinder and heat shields are being shipped to a contractor for electropolishing and nickle plating respectively. Copper dewar parts have been annealed and are ready for gold plating. The second set of low loss coaxial dewar lines were assembled and tested. Initial results look good. Addition testing will be done in the test dewar. Evaluation of components for the new post-dewar electronics design continues.

IF Improvements: All parts from the shop have been completed and construction started on the ORM power dividers and CF amplifier upgrades.

Penn Array: All necessary equipment has been gathered, cryogenic lines charged, and lab space made available for the Penn Array arrival this weekend.

Digital Electronics Status -- Randy

Digital Group Status 12-AUG-06 THRU 18-AUG-06

***Operations, Problem Summary***

No problems to report...

Active Surface...

No work was done on the Active Surface this week.

Miscellaneous...

• A spare actuator was cleaned up and delivered to the Science Center for public display.
• Some time was spent attempting to correct problems with the Science Center fire alarm system. More detailed technical documentation will be required to look into this further.

***Development***

Caltech Continuum Backend (CCB)...

Construction of CCB #3 is still underway with a newly revised completion date of 01-SEP-06.

Spectrometer LTA Re-design...

Work continues on the LTA re-design project... A detailed project schedule should be ready by 01-SEP-06. Following this, an informal preliminary design review will be scheduled for sometime in the mid- to late-September time frame.

Lab Spectrometer...

• When a second High Speed Sampler (ALMA #3) was added to the Lab Spectrometer, Roger's testing uncovered a problem with slot #3 in the sampler rack. Moving the new HSS into slot #2 corrected the problem; however the Lab Spectrometer exhibited some problems in powering up reliably. I'll look into these issues when I return from vacation.
• J.D. continued work on the design of a rack-mount 10MHz/1PPS signal generator for use on the Lab Spectrometer.

ALMA (As reported by Jason Ray)...

• CV reported that one connector was out of spec by 7um, on a measurement from pin 1 to pin 18. After some research, and help from Dennis, we determined that we cannot reject that connector based on that measurement because it really is in spec.
• Met with Manasseh regarding his work this summer since this is his last week.
• Worked with Carol regarding the soul source justification required for the Freedom CAD order.
• Three of the four SRI connectors were returned from CV following leak testing. They've already installed one of them into a Band 6 cartridge. CV reported these connectors have much better leak properties than the PAVE or PLUG-IN versions.
• Installed one of the connectors into our test 300k plate and performed the "mechanical fit test" with the new housing, rods, guide pins, etc. It works very well.
• Placed quite a few orders for hardware, components, etc. needed for the rev C2 run.

***Plans***

• Continue Active Surface maintenance as required...
• Continue construction of CCB #3...
• Continue work on LTA re-design and prepare project schedule...
• Continue work on 10MHz/1PPS signal source for Lab Spectrometer...
• Continue ALMA support as needed...

Randy

Software Status -- Mark

Beginning of cycle and entire group returning from Software Conference in Soccoro.

• Introduction and orientation for new member Ron Grider
• Work on recently requested enhancements to Penn Array software
• Continued progress on Zpectrometer
• Initial meeting discussing upcoming PTCS work
• Operator support pursuing ASTRID-hanging problem and special needs for PTCS observing scripts

Pulsar Related -- Scott

MIT/LL 43m Project -- Glen

Any other Business

-- RichardPrestage - 16 Aug 2006