If you want to build your own cable rather than purchasing a QYT USB cable , you will need a USB-to-TTL UART module.
The KT-8900 uses a standard Serial-to-TTL (3.3V or 5V) interface. While the port often accepts a 4-contact (TRRS) plug, it typically only uses three contacts: , Transmit (TX) , and Receive (RX) . Plug Contact Description Tip RX Data coming into the radio from the PC Ring 1 TX Data going out of the radio to the PC Sleeve GND Common ground for the circuit qyt kt8900 programming cable pinout top
: Ensure the radio is turned on and the correct COM port is selected in your software settings. Avoid using USB hubs. If you want to build your own cable
: Ensure the 3.5mm plug is pushed all the way in. The recessed nature of the jack sometimes prevents standard bulky plugs from seating correctly. Plug Contact Description Tip RX Data coming into
Connect the pin of the module to the Ring (TX) of the plug.
Connect the pin of the module to the Tip (RX) of the plug.
Some versions, particularly the KT-8900D, may feature a "DATA" jack on the rear panel. QYT KT-8900 Programming Cable Pinout