Note that the cold load (used to calibrate the noise temperature
of the receiver) is a conspicuous part of the system.
If you are interested in such things, you might want to bookmark
this page, because it is not super-easy to find by googling. It
uses some unexpected terms ("cold termination" instead of cold load,
and "cryogenic" instead of helium) and avoids expected terms like
"electronics" and "apparatus" ... thereby defeating the obvious
search attempts.