Re: [chirp_devel] VX2r

I wonder if I need a diode between the Tx and Rx lines.

Nope, you don't. Just tie the TX and RX lines together and feed them to the radio's data pin. Make sure your data and ground lines aren't switched.

Open a serial terminal (like minicom) and start the clone from the radio. See if you see any data, especially like AH0XX. If not, there's no communication. If you do, but it's garbled, then search for a suitable baud rate. If you see AH0XX, then you're off to mess with CHIRP code.