It looks like it works. i. but i guess the sx1278 needs more power then the nano 3.3v pin can provide?!?
Ok looks like the stop Dpwn converter makes all kinds of distortions. Could a capacitor help to balance the current?
edit: i did attach a 220mf capacitor right before the 3.3v in of the sx1278 on a not functional pice. And it works fine now. Just like the HT-12, the sx1278 seams to benefit from it.