And yet in Revenge of the Sith we see them building the dish as part of the frame of the station. Maybe it got broked up

You have to focus on what is available to know. At the end of RotS we see a Death Star being built. We don’t know if that is one and the same as the one in E4. That one could have, for all we know, blown up when they test fired it. If you read Cold War history or history of the space race you learn how many failures we had just trying to make one rocket that would launch the way that we wanted it to. Build - launch - blown up on the pad/crash/otherwise fail. Back to the drawing board and repeat the process again and again and again and again.