K2EXE-10 Winlink gateway

Sep 21, 2022 · 3 min read · winlink, gateway, emcomm

The full slide deck is still available: Bear Bait Radio Club — Winlink slides

Building your own? The hardware behind this gateway: Winlink gateway project kit on kit.co

What is Winlink?

Winlink is email over radio — a hybrid network of amateur radio and authorized government stations providing worldwide radio email using radio pathways where the internet is not present. It supports email with attachments, position reporting, weather and information bulletins, and is well-known for its role in interoperable emergency and disaster relief communications.

Key facts:

Built, operated, and administered entirely by licensed ham volunteers
Capable of operating completely without the internet via smart-network radio relays
Support provided by the Amateur Radio Safety Foundation, Inc., a US 501(c)(3)
Winlink Global Radio Email® is a registered trademark of ARSFI

Choosing a mode

Winlink runs over several radio modes, each with different speed, cost, and complexity tradeoffs:

Mode	Band	Speed	Notes
Pactor	HF	varies	Expensive proprietary hardware
Packet (AX.25)	VHF/UHF incl. 6 m	1200/9600 baud	Many software/hardware options
Robust Packet	HF	200/600 baud	WinRPR (Windows) or SCS TNC hardware
ARDOP	HF	500/2000	Built into Winlink Express; separate download for Linux/Mac
Vara HF	HF	up to 8490 bps theoretical (uncompressed, at S/N 14.5 dB @ 4 kHz)	Paid license
Vara FM	VHF/UHF	~18× faster than packet, via 9600 baud port	Free version has speed limits; $69 for both Vara apps

For first-time users connecting locally, Vara FM is the recommended mode — it’s far faster than packet and the free tier is enough to get started.

Gateway architecture

A Winlink gateway splits into two halves:

Station — the radio, TNC/modem, and software that talks RF
Network — the internet side that relays messages to the global Winlink system (RMS Relay handles store-and-forward between them)

K2EXE-10 gateway details


Frequency	145.050 MHz
Modes	Packet AX.25, Vara FM, and telnet via the AREDN mesh
Mesh hostname	`K2EXE-WL2K.local.mesh:8772`
Hardware	12 V DC Windows PC — runs entirely on 12 volts
Software stack	RMS Packet, RMS Relay, UZ7HO soundmodem (AX.25), Vara FM

Operating schedule: 24×7, best effort.

The telnet path is only exposed from inside the AREDN mesh — RF modes (Packet AX.25 and Vara FM) are the ways in from the radio side.

Signal flow through the gateway: RF → UZ7HO soundmodem or Vara FM → RMS Packet → RMS Relay → the global Winlink network (and back).

Finding other gateways

VHF/UHF gateway list: https://winlink.org/RMSChannels
HF gateway list: same page — filter by band

Peer-to-peer: no servers needed

Winlink also works entirely station-to-station: pick a frequency and mode, and send messages directly to another station. No RMS servers or post-office boxes involved — handy for two portable stations in the field.

Client software

Platform	Software
Windows	Winlink Express (the standard), Outpost, Airmail, Paclink (gateway for regular email clients)
macOS / Linux / Windows	Pat — lightweight CLI/web client
Android	WoAD

Location reporting

Winlink clients can report position, which feeds the APRS network:

Built into Winlink Express, Pat, and WoAD
Query for stations nearby: email INQUIRY@winlink.org with subject REQUEST and message body WL2K_NEARBY

WoAD also does position reporting directly from an Android phone — useful for mobile and portable ops. (Position reporting is a client-side feature; the K2EXE-10 gateway itself doesn’t gate APRS traffic.)