Strip the wire ends and apply a small layer of solder paste/tin to the bare copper.

Before diving into the pinout, let’s clarify a critical point of confusion. The QYT KT-8900 uses an connector for its microphone/speaker and programming port—similar to an Ethernet cable. When users search for the "top" connector, they are typically referring to one of two things:

Before you power on the radio and attempt to read the frequency data, verify:

You cannot wire a 3.5mm jack directly to a standard RS-232 serial port or a raw USB interface. The QYT KT-8900 communicates using .

: The programming jack on the back of the KT-8900 is often recessed into the case. Standard bulky 3.5mm plugs may not fit; use a "slim" style connector or a repurposed PC speaker cable for a better fit. Software Setup

The programming cable for the QYT KT-8900 3.5mm TRS (stereo) audio jack

📌 TXD (Transmit Data) -> Connects to the RXD pin of your USB-to-TTL adapter.

Looking at a standard , the top-to-bottom pinout mapping is:

Unlike many larger mobile transceivers that utilize the front RJ-45 microphone port for data transfers, the standard located on the back panel of the radio for programming.

Note: For the standard, cheap 3-pin USB programming cables (often identified as Baofeng/Kenwood style), the RX/TX wires must align with these pins. 3. Creating a Custom QYT KT8900 Programming Cable

. While some users have successfully used standard 3.5 mm stereo plugs, a 4-contact (TRRS) plug is often recommended for maximum compatibility Programming Port Pinout (3.5 mm Jack) For programming, only three connections are typically used RX Data (Data from PC to Radio) TX Data (Data from Radio to PC) Ground (GND)