during my test I had it some times. I remove the power from Pluto (in my case USB), shut down the SDR-Console, restart the PC, started the SDR-Console, ensured the bandwidth was in TX range during the Pluto selection (USB) and it worked again.
Not sure what the reason issued the problem but it worked again.
tnx for hint.
so far no success here ...
Problem solved ...
The cause of the grayed out TX part is the order in which the software is switched on.
If SDR Radio RX is started and then the TX part is selected, it remains gray.
If the RX part is on Stop, then TX is started, and then RX, then the TX part is ok.
Likewise, when TX is "docked". Then TX can be used immediately with every restart of the RX or the software and is no longer grayed out ....
Thank you all for help anyway ...
73´s de Robert
good hint and I will keep in mind. Maybe I did it your way as well and though it was a SW latch reason.