HBA summators completed

On Friday 13-Jul-2012, we finished installing all the summators in the high-band antenna tiles. This task has taken a long time, but we've finally made it!

Schematic of the HBA tile structure. (Autonational / ASTRON)

Thanks to everyone from SGO and ASTRON who took part in this work.

Summators (mostly) installed!

Here is the final photograph from the HBA summator installation. In the end we installed 48 Y-polarisation units and 42 X-polarisation units. We could not install the last few X-polarisation units, as we did not have a full set of parts. This work will be completed in July when the ASTRON team are back to do the next stage of the RF installation work.

Five of the HBA installation team (minus Joona... who took the photograph!).

A big thank you to all the team for their efforts in getting the job done in such a short time. Owing to the windy weather, it was just as well it was completed soon. But it had stayed dry, which was important... although with the consequence of a lot of static electricy, which meant we were regularly getting zapped!

The weather turns

Despite it being June, the weather wasn't always kind. High winds made life difficult for the installation work. However, the temperatures stayed cool, which was very welcome. We even had some snow as we were installing the last few units.

Only a few HBA tiles to go! (Photo: D. McKay-Bukowski)

In the background, you can see the mountains, but between the site and the mountains is Siilasjärvi, the nearest lake. Its surface, along with most of Kilpisjärvi itself, was still covered with ice.

Summator installation revisited

This panorama was taken from the top of the RF-container during the HBA summator installation week. Note the open tiles with the team busily connecting the new units.

HBA summator installation at KAIRA. (Photo credit: D. McKay-Bukowski)

In the background are Saana (left) and Pikku Malla (right). The Lehtinen Barracks are in the left foreground.

HBAs with Saana beyond

Just a nice photograph today. Again, this is one taken by our summer student, Joona.It shows the edge of the HBA tiles with Saana in the background. Despite it being mid-June, there is still a lot of snow on the mountains (and even still a bit on the site itself!).

Saana seen in the distance beyond the HBA tile edges. (Photo credit: Joona)

The photograph was taken during the summator installation week. And, yes, the weather was not going to remain perfect for us throughout!

Lying down on the job?

It may look comfortable, but installing the summators was seemingly neck-breaking work. To reach into the tile, you have to lie on your stomach. Your hands are busy connecting cables so you can't support yourself with your arms. And, holding your head out to see what you are doing puts a strain on the neck.

Trying to make the most of the good weather, we had multiple tiles undergoing HBA summator
installation at once. In the background is Saana. (Photo credit: D. McKay-Bukowski)

Add to this the constant climbing up and down off the 2-metre high tiles and by the end of each day we were all exhausted.

Installing the summators

To install the summators, the HBA tiles must be opened up.

The team peel back a cover and remove one of the cell lids. (Photo credit: Joona)

Then the cell arc is removed, the summator attached, and the cables connected. Tests are done to check the resistance of the summator, and thus check for any failed circuits.

An ASTRON engineer fits a Y-polarisation summator. Note the test equipment on the cover nearby. (Photo credit: Joona)

There are two summators per tile, so after the X-polarisation summator is done, the adjacent cell is opened to the done the Y-polarisation. Finally, the covers are all put back, and the anchor lines re-attached to the timber frame sets.

RAL and SGO staff re-secure the cover on one of the tiles. (Photo credit: Joona)

It is tricky work. With so many cables, one must be very careful to ensure that no mistakes are made. We had a system of checking and cross-checking each others work to ensure that the installation was error-free.

HBA summators

The HBA (High-Band Antenna) summators are units that reside inside the HBA tiles. They act as analogue beamformers, providing an initial level of control to steer the tile primary beam over the sky.

From front to back: a Mark-I summator, two Mark-II summators and
another summator still in its anti-static bag. (Photo credit: Joona)

There are two designs: the older "Mark-I" design uses a sheet-metal box. They are nominally okay, but in the Netherlands where there are high moisture levels, condensation causes some failures. The newer "Mark-II" design is completely encased in black resin (similar to the LBA low-noise amplifier units). These are more robust. For KAIRA, our installation comprises Mark-I summators for the X-polarisation and Mark-II summators for the Y-polarisation. Normally summators are installed in the tiles as they are assembled in the factory. However due to unit shortages in 2010 and 2011, we had this postponed. This means that the summators must be installed in situ. This work was carried out last week, and we'll be reporting on the work over the next couple of days.

ASTRON arrives

Last week a couple of engineers from ASTRON arrived to install the HBA summators at KAIRA. The next few posts will be from that visit.

Members of the HBA installation team.(Photo credit: Joona Keskitalo)

First summator!

Almost first light! On November 11th 2011 we installed the first two summators into the HBA panels with the idea that these can be used to test the signal processing hardware inside the RF container. These summators were the first from the newly designed batch of summators produced by Astron, hopefully fixing some of the problems with moisture that were experienced with the old version. The wintering of these newly designed summators will also be a test of their durability as well. 

We are still missing 46 summators before the system is fully operational. However, we will have to wait until spring 2012, as it isn't possible to perform the installation during winter due to increased risk of static electricity discharge and pure inconvenience. 

The green cables seen inside the HBA tile are connected to the summator, which is responsible for the first level of coarse grained beam forming, implemented using a set of switchable delay lines.    

Installing the summators.