Thanks for your answer. Yes, we stand at the total beginning. complex solderwork is normaly no problem, but BGA is the firt time, and before I kill a over 100$ chip I first make some prepeartions, and look arround how others did this work. It's completely no need to finish this project in the next days. I also thinking of buying a cheap BGP soldering "machine", because we built here several pieces because we are an international group of HAM's who built together since years. Most of them comes from the UHSDR project. We bult many boards and complete TRX based on the UHSDR software, but som with modifications or other formfactors. Also a very nice project and much easier than the odyssey, but also not for beginners.
The last TRX I built is a Sparrow 4 Inch. Also very portable (formfactor of a KX2 from Elecraft), 20W output and all HAM Bands (6m only RX or very littel output, because the PA is not usable for 6m). There's a 4 Inch Touch Display with Waterfall and Spectrum and many other nice functions like built in FreeDV.
Left: SParrow 3.5 Inch
Right: Sparrow 4 Inch