thank you for your tips!
i was able to setup my rfd with your suggestion. i did buy a new 4dbi antenne.
i use sik 2.5
i tested coverage with my car and was able to get signal ~5 km.
if everything is ok i will take rfd from my roof to my silo 15 m above ground and test again.
an other question: i was not able to turn ecc =1. is error connection usefull for reach?
sometimes signal is not good and delayed up to 10 seconds.
at the moment i use adr 24 with 30 % duty cycle.