Qyt Kt8900 Programming Cable Pinout Top -

Before we dive into the pinout, a word of caution. Many operators assume the QYT KT-8900 uses the same standard Kenwood-style K1 connector found on Baofeng UV-5Rs or Quansheng radios.

It does not.

While the connector looks similar, the QYT KT-8900 often utilizes a slightly different interface or requires a specific variant of the programming cable. Using the wrong cable or forcing a connector can damage the radio’s port.

Early QYT KT8900 units (pre-2017) used a different pinout: Pin 2 was RX and Pin 3 was TX. Later revisions standardized to the pinout above (Pin 2 = TX). If you have an older radio, you may need to try the reversed pinout:

This explains why so many online forum posts contradict each other. Always check your radio’s firmware version: Hold the PF1 key while powering on. Firmware 2.07 and later use the modern pinout. qyt kt8900 programming cable pinout top

The QYT KT8900 is a popular mini mobile ham radio, but like many Chinese radios, it uses a non-standard Kenwood-style connector for programming—not the standard 2-pin or 8-pin mic connector you might expect.

The KT-8900 follows a non-standard (but common among Chinese mobile radios) serial TTL logic. Important: This is NOT a standard RS-232 cable. It uses TTL levels (0-5V), so a simple USB-to-serial adapter with a MAX232 chip will NOT work. You need a USB-to-TTL adapter (e.g., using a CP2102, CH340, or FTDI chip).

Here is the definitive pinout for the RJ-45 connector that plugs into the radio’s front panel "MIC" port (the "top" connector):

| Pin Number | Signal Name | Wire Color (Typical in OEM Cable) | Function | | :---: | :---: | :---: | :---: | | Pin 1 | NC / GND | Black | Not connected in programming mode (ground on some versions) | | Pin 2 | SPK- (Speaker -) | Yellow | Negative speaker line (not used for programming) | | Pin 3 | MIC / TXD | Blue | Programming Transmit Data (Radio → PC) | | Pin 4 | PTT | Green | Not used during programming | | Pin 5 | GND | Brown | System Ground (critical for programming) | | Pin 6 | RXD | Red | Programming Receive Data (PC → Radio) | | Pin 7 | VCC / 5V | Orange | +5V power from radio (only active when radio is ON) | | Pin 8 | SPK+ (Speaker +) | White | Positive speaker line (not used for programming) | Before we dive into the pinout, a word of caution

| Symptom | Likely Pinout Issue | Fix | |---------|--------------------|-----| | "Radio not found" | Pin 2/3 swapped, or GND missing | Swap TX/RX; check Pin 1 continuity | | Timeout after reading 1% | +5V on Pin 6 is missing | Bridge +5V from USB adapter (if ≤100mA) | | Garbage characters in terminal | Incorrect baud rate | Ensure 9600, 8N1, no flow control | | Radio resets when plugging cable | GND loop or 5V short | Add a 100Ω resistor on Pin 6 |

| Plug Type | Tip (T) | Ring (R) | Sleeve (S) | Function on KT8900 | |-----------|---------|----------|------------|--------------------| | 3.5mm | Data TX (radio transmit) | No connection | Ground | Sends data from radio to PC (for reading) | | 2.5mm | Data RX (radio receive) | No connection | Ground | Sends data from PC to radio (for writing) |

Ground is shared – both plugs’ sleeves are connected internally.

If you are a DIY enthusiast and want to solder your own interface, remember that the pinout on the radio side is standard 3.5mm TRRS, but the pinout on the USB side depends entirely on your USB-to-TTL adapter board. This explains why so many online forum posts

Crossing these wires is the fastest way to frustrate yourself, so double-check with a multimeter continuity test before plugging it in.

| USB-to-TTL Adapter Terminal | Connect to RJ-45 Pin (on the "top" plug) | | :---: | :---: | | GND | Pin 5 (Brown wire) | | TXD (Transmit from PC) | Pin 6 (Red wire) – note: this goes to radio’s RXD | | RXD (Receive from PC) | Pin 3 (Blue wire) – note: this goes to radio’s TXD | | 5V (VCC) | Pin 7 (Orange wire) – optional but recommended |

Important cross-wiring rule: On the USB adapter, TXD must connect to the radio’s RXD (Pin 6). Similarly, the adapter’s RXD connects to the radio’s TXD (Pin 3). This is a classic null-modem style connection.