As you can see, even among Chinese radios using RJ-45, the pinout varies. The KT-8900’s configuration (with Pin 3 as TXD and Pin 6 as RXD) is unique to the QYT KT-8900, KT-8900D, and KT-UV980. Do not assume compatibility with any other radio.
Note: Some variant cables use a 4-contact TRRS plug, but only the first 3 contacts (Tip, Ring 1, and Sleeve) are utilized. A standard 3.5 mm stereo TRS plug works perfectly. 🛠️ DIY: How to Build Your Own KT-8900 Cable
To interface this radio with a computer, you cannot use a straight-through audio cable. You must use a USB-to-TTL serial adapter module (such as an FTDI, CP2102, or CH340 chip) that operates at . The serial adapter translates the computer's USB signals into the asynchronous serial data that the radio's microprocessor understands. Exact Pinout Configuration
: Most commercial cables utilize the Prolific or CH340 chipsets. qyt kt8900 programming cable pinout top
Completely power down the radio before plugging the 3.5mm jack into the back panel. This prevents voltage spikes from corrupting the microcontroller's memory or freezing the interface.
Various diameters to insulate individual solder joints and provide strain relief. 4. Step-by-Step Assembly Instructions Step 1: Prep the Cable and Connector
Building your own cable is inexpensive and straightforward. Here's a step-by-step guide, aggregating information from the Miklor.com project page and community forums. As you can see, even among Chinese radios
Note: For certain hardware production runs, the TX and RX lines on the Tip and Ring 1 may be reversed. If your initial build fails to read the radio, swap the TXD and RXD wires on your converter board. 3. Required Components and Tools
If you are trying to build your own cable or repair a broken one, the layout on the PCB inside the connector shell is crucial. The standard "Kenwood 2-pin" style (which many mistakenly try to use) separates the Speaker and Mic into two distinct plugs. The QYT KT-8900 often uses a single 3.5mm jack that handles both audio paths. If you wire the Tip to the wrong data line on your USB adapter, the radio will not enter programming mode.
: A sacrificial male-to-male audio cable with a narrow collar. Soldering Iron and Heat Shrink Tubing . Wiring Schematic (USB Adapter to 3.5mm Jack) Note: Some variant cables use a 4-contact TRRS
While the physical port looks like a standard headphone jack, it carries serial TTL data. To program this radio, you only need three active connections.
: Ensure you have the correct drivers for your cable's chipset. Modern systems (Windows 10/11) often prefer FTDI or CH340 chips over older Prolific chips, which may require specific legacy drivers to function.
If you have built or bought a cable and receive "Radio did not respond" or "Failed to enter clone mode" errors in CHIRP, check the following variables:
To build your own QYT KT-8900 programming cable, you will need three basic components:
An FTDI Friend or a CP2102 UART module is highly recommended. (Avoid cheap Prolific chips as they frequently trigger driver errors in Windows 10 and Windows 11).