I thought I’d do a quick write up whilst I was developing the TOADs Digital Interface Daughterboards with some information about the 6 Pin Mini DIN DATA jack you find on the back of most mobile transceivers from brands such as Yaesu, Icom and Kenwood.
It seems at some point the radio manufacturers agreed to use this as a “standard”.
The Purpose of the 6-Pin Mini-DIN
The 6-pin Mini-DIN is commonly used on modern Yaesu, Icom, and Kenwood FM transceivers to interface with external audio devices like sound cards or TNCs (Terminal Node Controllers). It allows your radio to send and receive audio data for digital modes, as well as handle push-to-talk (PTT) control.
Interestingly, while the physical connector and pinout are nearly identical across brands, there’s often confusion around what each pin actually does—mainly due to misnumbering or mislabeling in diagrams.
‼️ IMPORTANT: Understanding “DATA” vs. “Audio” Terminology Radio manufacturers often use the term “DATA” to refer to connections intended for TNCs or packet modems. In reality, these are audio lines, not digital data lines. For clarity throughout this guide, you can interpret “DATA” as “Audio”. Baud rates (1200/9600) referenced below relate to audio filtering and are explained in more detail later
‼️IMPORTANT: It is the user’s responsibility to verify compatibility and correct wiring for their specific radio. Refer to your radio’s manual for exact details.
Pinout Description
Pin 1: TX Audio In (DATA IN)
This is the transmit audio input (Mic Input) into the radio.
In 9600 baud mode, the audio is fed directly to the modulator (flat, unprocessed).
In 1200 baud mode, the radio applies pre-emphasis and filtering (processed audio).
Selecting audio is usually done in the menu (or via jumpers depending on the radio) Yaesu FT-8900: Menu #26 (PCKT S) • Kenwood TM-D710: Menu #518 (EXT.Data Speed). Consult your radio’s manual for exact configuration. In most cases, using 1200 baud (processed audio) works reliably for most applications.
Pin 2 – GND
Pin 3: PTT (SEND)
Grounding this pin switches the radio to transmit mode. Used by external sound cards or software to key the transmitter.
Pin 4: RX Audio Out (Unprocessed, “9600 Baud Output”)
Direct discriminator audio—no filtering or de-emphasis. Ideal for high-speed digital modes.
Pin 5: RX Audio Out (Processed)
Audio that’s been filtered and de-emphasized, like what you’d hear from the speaker.
Pin 6 – PKS / Squelch Logic Mute/squelch indication logic, active high or low (selectable).