Yesterday I already found gain control :-) but furthermore no success.
This morning I began to check my complete equipment first SW and then HW. And now, thank god, the problem is fixed.
The issue was in polarization switching which I forgot. After increasing supply voltage for lnb to 18V I got a proper signal on spectrum display.
Now I can go further, thank you for your support.
Vy73 de Achim DL3RY