Category: AMiBA/MLO

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Hibernation Effort

Yesterday (Dec 9) Peter and I went up to ML to work on the following:

  • Remove Heliax cables – Together we were able to remove 29 cables that consisted of a mix of 9-m, 7-m, and 2-m lengths.  The cables are stored in the support cone below the telescope and are separated by lengths.  We believe we can complete the removal of the Heliax cables within the platform with 2 more days of work (requires two persons).
  • Repair right rear exist frame – When we arrived we noticed the metal structure holding the canopy down had broken away.  It turn out that the two bolts holding it down were stripped (possibly wrong size to start?) so we replaced them with the correct size.  Photo after repair shown here.
New hold down bolts, this one showing the left side.
Photo of frame after replacing hold down bolts.  The horizontal curved support structure that came loose is circled in blue.  
  • Remove AC plugs for ROACH-2 chassis –  When we arrived we found 2 of the 4 ROACH bays were powered up unintentionally via the WTI network power switch, probably as a result of a power failure recovery routine.  In order to prevent this from happening in the future we removed the AC power plugs to the rear of all 32 ROACH-2 units.  We left the WTI units powered on so that we can perform remote reboots of network switches and other accessories.
Photo of on of the four ROACH-2 bays with WTI Network Power Switch at top.
  • Pull long extension cord from Eaton UPS to Control Container – Being that we will no longer power up the ROACH-2 hardware, we decided to use the large Eaton UPS, model 9170+, to power the PCs and other accessories within the Control Container.
Eaton 9170+ UPS
Yellow power cord carrying UPS power into Control Container.

I’ve attached the 6 views of the telescope as it stands today.  There is still much to do but hopefully with the stiff Heliax cables out of the way things will go a bit faster.

-Peter, Derek

View 1
View 2
View 3
View 4
View 5
View 6
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Preparing for hibernation mode

Today Adam and I were at the site preparing the hardware to go into hibernation mode. The ROACH2’s and helium compressors were powered down, which was sad to do. We also opened the shelter to take some pictures of the newly coated dishes and also to patch the shelter fabric.

Adam took pictures of the primary and secondary dishes and emailed them to Sally in Hilo to upload into the dish database. On Thursday, I will have Casandra measure the resistance measurements of the primary and secondary.

Adam also assembled 2 storage racks that went into the storage container and on Thursday, Adam will assemble 2 more that will go into the sleeping container.

I took some pictures of the hardware today and asked Sally to create a YTLA database just for the pictures, so that we will know the location of each hardware, if we need to put it back in the future.

On Thursday, Adam, Casandra and I will start bringing down 2 dishes off the platform to transport down to the hilo lab.  Also we will be organizing the sleeping rooms for the storage racks.

Adam, Sally, Casandra, Peter

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Night observations canceled tonight

The vacuum pump for Rx4 and Rx5 failed overnight and was unable to pump down these two receivers. There was also a burning smell coming from the pump. It has been turned-off and put on the side and is not usable. Rx1 and Rx6 are currently cooling, so once the are cooled tonight, then I can use their pumps for the pump down on of Rx4 and Rx5 on Wednesday and cooling will be done on Thursday.

Also the weather forecast does not look good for tonight and wednesday.  So hopefully on Thursday, the receivers will be cold and the weather improves for observations.

Peter

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Site update for 10/8/21

Rx6 is cooled down for tonight observations. I had to turn off the cold head for Rx4. The receiver was cold at 15K but the cold head was making a bad ratcheting sound. It will not be useable for tonight’s observations. So it will be pumped down on monday and cooled on Tuesday. For tonight, there are 6 cold receivers.

I checked on Rx2 Y-pol for any loose connectors that might have caused the power drop-out on Wednesday night. There was one loose connector. It was not that loose but we’ll see if that fixes the power drop out.

Peter