Which Interface? OpenTNC vs. AIOC
A common question for new and experienced hams is which digital interface is best for me. This page aims to serve as a clear comparison between the OpenTNC vs AIOC.
Comparison Matrix
| Specification / Feature | OpenTNC | AIOC |
| Role |
Standalone hardware packet TNC for base and mobile stations | Combined programming cable and sound card interface for handhelds (HTs) |
| Modem Architecture | Hardware modem: AX.25 (de)modulation handled on-device | Software modem: Host computer handles (de)modulation (Direwolf, etc) |
| USB Communication | USB CDC-ACM Serial Device | Composite USB audio + HID + CDC-ACM serial |
| Operating Modes | Packet Terminal Mode, KISS Mode, and Digipeater Mode | Audio pass-through + serial PTT/programming |
| Configuration | On-board software/hardware configuration | Host software managed + limited onboard configuration |
| Standalone Modes | APRS/AX.25 DigiPeater | Fox-hunt mode |
| Radio Interface | DE9 Port (Kantronics pinout); Mini-DIN6 and K1 cables available, or make your own | Integrated Kenwood K1 2-pin connector to plug directly into HT radio |
| Audio Calibration | Factory calibrated; Output level potentiometer | Levels adjusted in host OS volume sliders and gain |
| Enclosure | Rugged aluminum enclosure with status LEDs | Bare board kit with optional 3D printed enclosure |
| Price | $99 Kit | $20 (DIY) / $33 Assembled |
OpenTNC: Standalone Hardware Packet TNC
The OpenTNC is a self-contained packet controller engineered for mobile rigs and base stations. It eliminates host-side software modems and sound card calibration by running the packet protocol stack directly on the hardware.
- Standard USB Serial Interface: Communicates with the host PC, Raspberry Pi, or terminal over a standard USB CDC-ACM serial connection. It requires no specialized sound card drivers, virtual audio cables, or OS audio routing.
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Persistent Hardware Configuration: All operating parameters—including callsigns, audio levels, TX delay, and operating modes—are stored in non-volatile on-board memory. Once configured via the command prompt, settings persist across power cycles without relying on host-side config files.
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Autonomous APRS Digipeater Mode: Operates independently in the field without a connected computer. When supplied with standard 5V USB-C power (from a wall adapter or USB battery bank), the OpenTNC performs on-board APRS packet digipeating, including full support for standard `WIDEn-N` path substitution and alias handling.
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Dual Operational Modes: Supports traditional command-line Terminal Mode for interactive packet BBS and keyboard-to-keyboard sessions, alongside standard KISS mode for Winlink Express, APRS client software, and network stacks.
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Standard DE9 Interface: Built using the industry-standard Kantronics 9-pin pinout. Standard cables connect directly to the 6-pin Mini-DIN data ports found on common mobile transceivers:
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Yaesu: FTM-6000R, FTM-300DR, FTM-400DR, FTM-500DR, FT-7900R, FT-8800R, FT-8900R
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Kenwood: TM-V71A, TM-D710G
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Icom: IC-2730A, IC-208H
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Alinco: DR-135T, DR-235T, DR-435T
- Or build your own cable or use the K1 cable for HTs.
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Yaesu: FTM-6000R, FTM-300DR, FTM-400DR, FTM-500DR, FT-7900R, FT-8800R, FT-8900R
AIOC: All-In-One-Cable for Handhelds
The AIOC consolidates an audio interface and a programming cable into a single compact board for handheld transceivers (HTs).
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Replaces Multiple Cables: Replaces both a dedicated FTDI programming cable and an external sound card interface (such as a Signalink or generic USB audio dongle) with a single compact adapter.
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Direct K1 Connection: Plugs directly into radios using the standard Kenwood K1 2-pin connector, including Baofeng (UV-5R, BF-F8HP), Quansheng (UV-K5), AnyTone (AT-D878UV), and Kenwood HTs.
-
Software-Defined Audio Interface: Enumerates as a standard USB audio card and virtual COM port. Packet modulation and demodulation are performed by host software (such as Direwolf for packet/APRS or VARA FM) running on a connected PC, Raspberry Pi, or Android device.
- Integrated CHIRP Programming: The virtual COM port provides direct TX/RX serial lines to the radio's baseband processor for frequency and memory programming via CHIRP without swapping cables.
Choice summary
Choose the OpenTNC if:
- You are interfacing with a mobile rig or base station via a data port, or
- You want a dedicated hardware packet engine using standard USB serial, or
- You require configuration parameters stored on the device, or
- You need autonomous APRS digipeating powered simply by a 5V USB-C supply.
Choose the AIOC if:
- You are using a handheld transceiver with a K1 connector and want a single compact cable that handles both CHIRP memory programming and software-defined sound card modes via host software.