Quick reference for installing the TCXO on a HackRF One.
The TCXO module gets installed on the 12-pin P22 connector on the HackRF One. You will want to install the module on pin 1, which is closest to CLK IN / OUT on most boards.
To test, you will want to run the following command, which can be built from the HackRF source:
If all is working, you should get the following output:
If your output does not match this, that means that the TCXO is not being used. The HackRF One firmware may need to be updated.