Problem with high power mode

[LordDuplo]

Hi,

i have a problem when switching IS_RFM69HCW true.

When the option is set to false and i open the serial monitor on the sender all works fine.
I can see that the arduino pro mini sends the correct values.

But when i switch the option to true the serial output looks strange.
And after a while the arduino crashs.

Do you know why?

My setup is the following:

Gateway: Wemos D1 Mini with RFM69CW
Sender: Arduino Pro Mini 3.3V 8 Mhz with RFM69HW