An XG3 Data cable is required. Plug the 3.5 mm stereo plug into the jack labeled "PC" on the top right of the XG3. Connect the DB-9 end of the XG3 Data Cable to an RS-232 serial port on your personal computer.
If no RS-232 serial port is available, a USB to Serial Adapter, such as the Elecraft KUSB, may be used.