Actually, I needed to change 2 things: first one was dividing by 1000.0 rather than 1000 and the other one was calling send(msgVcc.set(Vcc, 2)); rather than send(msgVcc.set(Vcc)); Now the log reads 2.95V.

Thanks Mikael (@mfalkvidd) & everyone! Happy coding!

Yes Mikael, but it suddenly hit me that you have to allow Domoticz to add new devices from the console. I can see the Temperature and the Humidity now!

Thanks again!

Thanks for your reply!

It appears to be a newby mistake: I overpowered the NRF24L01 radios: the FTDI board did put out 5.0V although the output Voltage selectors witch wat at the 3.3V position..

Another lesson learned today... always doublecheck !