Karsten, I have created a mini builder's manual for the ubitx, it just basically compiles the assembly instructions and firmware functions into a pdf file for easier reading. Hopefully this helps you out a little bit. If theres any specific use case you need covered, feel free to ask me and I will do my best to add it into the pdf.
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist