If this is the first time you have powered on your radio with theCrossfire transmitter in, make sure you put on both antenna. The Crossfire antenna and the radios antenna.
After you have powered on your radio, go into the models list in OpenTX. Select the model you need to change and go to Model Setup page 2. At the bottom of page 2 look for Internal RF.
Select the mode value and change it to Off.
The next option down is External RF. Change it to CRSF.
Leave the ch. range at CH1-16. We manage the usage of channels after we connect to the receiver.
Once set you will notice the Crossfire transmitter led pulse yellow.
This model on your radio is now configured to use the external Crossfire transmitter.
Next we need to connect it to a nano receiver.