I think the problem it's about the micro. In the prototipes that has the problem, I change it and now they run until 2,0/2,1 V. The question is: what will appen when I'm start to produce the cards? Thanks for yours answers.
Do you mean the CLKO from the radio is not working (you can't measure it) or it is there and the MPU section acts like it is not there? Or something else completely?