Amateur Radio Emergency Services Association (ARES)

 Sumter County, Florida

Winlink Terminal Node Controller

Terminal Node Controller (TNC)

A terminal node controller is a device used by amateur radio operators to participate in AX.25 packet radio networks.  It is similar in function to the Packet Assembler / Disassemblers used on X.25 networks, with the addition of a modem to convert base band digital signals to audio tones.

TNC's were necessary when home computers lacked the sophistication needed to simultaneously manage a network connection and and communicate with the user.  Now, more powerful desktop or laptop computers are commonplace with amateur radio stations.  Software modems using the computer's sound card have lowered hardware requirements even further.  However, with their lower cost comes additional tweaking in order to make them work properly, and they often do not provide the decoding capabilities at low Signal / Noise rations.  Some handheld and mobile VHF radios currently on the market incorporate TNC abilities within the radio itself in support of the APRS and other protocols


A digipeater is a station that does digital repeating.  Unlike full-duplex VHF/UHF voice repeaters a digipeater will receive a packet of data, reprocess it, and retransmit on the same frequency.  A digipeater which operates on multiple frequencies is called a gateway.

Partial List of Terminal Node Controller for Winlink Express

Byonics: Tiny Track4 - $75, $140 w/GPS

  • KISS TNC - Connect to a computer and operate standard packet, Winlink, and any of the APRS software.
    APRS Digipeating - The TinyTrak4 can act as a smart APRS digipeater supporting WIDEn-N, callsign substitution, and dupe checking.
    Field Upgradeability - New firmware can be downloaded for free from the TinyTrak4 website and sent to the TinyTrak4 with a computer serial port and a F-F null modem adapter.

The TinyTrak series is one of the most popular on the raod.  Small and purpose-built, the latest TinyTrak can double as a TNC for your Winlink or any other packet needs.  It's also the cheapest digipeater solution that I know of.  If it is hooked up to a compatible GPS, it can display the locations of other stations.

TNC-X (MFJ-1270X - $129.95

TNC has a optional USB interface, 1200 baud, KISS Mode, and is used with terminal software such as Pr4Win.




SignaLink USB or SignaLink RJ45  - HRO $104.95

  • FCC Class B Certified

  • Built-in low-noise sound card

  • Simple installation and setup

  • Complete radio isolation

  • USB port powered

  • Works with virtually all radios

  • Use Mic, Data, or Accy Port

  • Supports virtually all sound cards with digital and voice modes

Kantronics KPC-3+ Packet Communicator - HRO $199.95

As a single-port radio modem/TNC compatible with the characteristics of UHF/VHF transmission bands, the KPC-3+ can be paired with a UHF/VHF radio.
Functions: "Keyboard to keyboard" communications, Digipeater Personal Mail Box, Local area node, Remote control devices, Remote access of telemetry, Network node operation, BBS operations and message forwarding
GPS position transmitting and tracking (requires external GPS receiver with NMEA-0183 data output), Data storage and retrieval , EMWIN Weather Information (additional software required)

SCS P4dragon DR-7800 HF Modem ( $1849)

Operating modes: PACTOR-4, 3, 2, 1, Weather-Fax (receive), GPS decoder

Software compatible with AirMail, RMS Express, Alpha, etc.


 Last Update:  09/12/2016    Copyright Sumter County ARES. All Rights Reserved.