Just found this thread having been reading up on 1420MHz Hydrogen line imaging (I'm a radio amateur and professional software developer). Great amount of info here...many thanks to everyone
I have noticed that some people are adding Satellite boosters after the pre-amp? Normally the pre-amp should provide enough gain to overcome any feeder losses down to the receiver and also alleviate receiver sensitivity issues, so I'm not sure why they are required? Also the boosters seem to be 75ohm which means a mismatch and consequent signal loss unless there is some matching being implemented? I'm sure there is a good reason just can't understand it at the moment. A lot of good work going into this though.
I'm looking into doing the same but extending to 2 dishes with interferometry, although finding a location for them (I'm in South Devon) may be problematic (back garden, I've been strongly informed, isn't appropriate.....).