|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.