VARA HF and VARA FM: The Digital Modes Powering Winlink

VARA has quietly become the dominant digital mode for Winlink email-over-radio — and for good reason. It's faster, more reliable, and better at handling poor conditions than the alternatives. If you use Winlink (or plan to for emergency communications), you'll almost certainly be using VARA. Understanding what it is, how it works, and how to set it up removes the mystery from one of ham radio's most practical digital tools.

I switched from ARDOP to VARA two years ago and immediately noticed faster connections, higher throughput, and fewer failed sessions. It's not perfect, but it's the best we have for reliable HF data transfer.

What VARA Is

The Basics

VARA (by EA5HVK, José Alberto Nieto Ros) is a proprietary digital mode protocol:

• Purpose: Transfer data (email, files, messages) over radio
• Medium: HF (VARA HF) or VHF/UHF FM (VARA FM)
• Type: Adaptive modem — automatically adjusts speed based on conditions
• Primary use: Winlink email system
• Cost: Free version (limited speed) or paid license ($69 each for HF and FM)

How It Works

VARA as a modem:

• Takes data from Winlink (email text, attachments)
• Converts to audio tones (modulates)
• Sends audio tones through radio transmitter
• Receiving station's VARA demodulates audio back to data
• Adaptive: changes modulation scheme based on signal quality

Adaptive speed:

• Starts connection at low speed (robust, works in poor conditions)
• If signal quality is good: automatically shifts to higher speed
• If conditions degrade: drops back to lower speed
• All transparent to the user (happens automatically)

VARA HF vs VARA FM

VARA HF Performance

Speed Tiers

Free version: Limited to ~175 bps maximum (very slow — but works for short messages)

Licensed version ($69): Full speed up to ~8,400 bps

Practical throughput on HF:

• Excellent conditions: 2000-5000 bps
• Good conditions: 1000-2500 bps
• Marginal conditions: 200-800 bps
• Poor conditions: 50-175 bps (still connects when others fail)

What This Means for Email

Practical limit on HF: Keep messages under 50 KB for reasonable transfer times. Plain text email works great. Large attachments: use VARA FM or wait for good conditions.

Comparison to Alternatives

VARA's sweet spot: Much faster than ARDOP, nearly as reliable as Pactor (at fraction of cost), and actively maintained.

VARA FM Performance

Speed

VARA FM on VHF/UHF:

• Narrow (1200 Hz): ~2400 bps max
• Wide (9600 Hz FM deviation): ~25,000 bps max
• Typical practical: 10,000-20,000 bps on clean VHF links

What this means:

• 50 KB email: 20-30 seconds
• Larger files: manageable (even ICS-213 forms with attachments)
• Approaching packet radio speeds without the complexity

Use Cases

• Local Winlink gateways (city/region coverage)
• Public service events (marathons, parades — fast message traffic)
• Emergency operations (shelter-to-EOC communication)
• Where internet is down but local radio infrastructure exists

Setting Up VARA

Hardware Requirements

VARA HF:

• HF radio with SSB capability
• Sound card interface (USB audio) or radio with built-in USB audio (IC-7300)
• Computer (Windows required — VARA is Windows-only software)
• CAT control (radio frequency/mode control from computer)

VARA FM:

• VHF/UHF FM radio
• Sound card interface (SignaLink, Digirig, or radio's built-in USB)
• Computer (Windows)
• PTT control (VOX or CAT or hardware PTT)

Software Stack

The typical setup:

1. VARA modem (vara2.exe for HF, varafm.exe for FM) — the modem itself
2. Winlink Express (or Pat) — the email client
3. Hamlib/OmniRig — radio control (optional but recommended)

Installation order:

1. Install Winlink Express
2. Install VARA HF and/or VARA FM
3. Configure audio device in VARA (select your sound card/USB audio)
4. Configure radio control in Winlink Express
5. Configure Winlink Express to use VARA as transport

Configuration Essentials

VARA HF settings:

• Sound card: select the correct USB audio device (the one connected to your radio)
• Audio levels: critical! Too high = distortion = failed connections. Start at 50% and adjust.
• BW (bandwidth): 500 Hz for crowded bands, 2300 Hz for best speed when possible
• PTT: COM port, CAT, or VOX (CAT most reliable)

Critical: Audio levels

• VARA has a built-in tuning aid (shows audio levels)
• Transmit audio should NOT cause ALC action on radio
• ALC meter should show zero or minimal deflection
• If ALC deflects: reduce audio output from computer
• Receive audio: VARA shows received signal level — should be in green zone

Using VARA with Winlink

Making a Connection

To send/receive email via VARA HF:

1. Open Winlink Express
2. Select "Vara HF Winlink" session type
3. Choose a gateway station (Winlink lists active gateways)
4. Click "Start" — VARA establishes connection
5. Email exchanges automatically
6. Connection closes when done

Gateway selection tips:

• Choose gateways you can hear well (propagation appropriate)
• Check channel reports (Winlink shows recent connections)
• Try different gateways if first attempt fails
• Off-peak hours: easier connections (less competition)

Peer-to-Peer (P2P)

Direct VARA connection between two stations (no gateway):

• Both stations agree on frequency and time
• One station calls, other answers
• Email transfers directly between them
• No internet required anywhere in the chain
• Pure radio-to-radio communication

Connection Tips

For reliable VARA HF connections:

• Frequency accuracy matters (within 50 Hz of gateway's listed frequency)
• SSB mode with NO processing (flat TX audio, no compression, no EQ)
• Disable speech processor, compressor, DSP TX enhancement
• Power: 50-100W typical (more isn't always better — clean signal matters more)
• Antenna: whatever you use for SSB voice works

Limitations and Considerations

Windows Only

VARA runs only on Windows:

• No native Linux version (Wine partially works, unreliable)
• No macOS version
• This frustrates Linux-loving hams
• Alternative for Linux: Pat client + ARDOP (but slower)
• Some success with Windows VM on Linux (latency-sensitive)

Paid License

Free vs Licensed:

• Free version works but speed-limited (~175 bps on HF)
• Licensed version: $69 per mode (HF and FM separate licenses)
• For emergency preparedness: $69 is worth it (speed during emergencies matters)
• For casual use: free version handles short text messages adequately

Proprietary Protocol

The philosophical issue:

• VARA is closed-source proprietary software
• Some hams object to this (prefer open protocols)
• But: it works better than open alternatives currently available
• Practical operators use what works; idealists wait for open solutions
• ARDOP is open but significantly slower and less reliable

Frequency Coordination

VARA HF needs clear frequencies:

• Typically operates on Winlink-designated HF frequencies
• Some interference from other users on shared bands
• Automatic frequency selection available in newer versions
• Listen before connecting (don't start on an occupied frequency)

Emergency Preparedness with VARA

Why VARA Matters for EmComm

When internet and cell towers fail:

• VARA + Winlink = email capability over radio
• Send messages to any email address (via Winlink gateway with internet access)
• If NO internet exists anywhere in range: peer-to-peer still works
• ICS forms, welfare messages, logistics — all transferable
• Faster than voice relay for detailed information

Practice Now

Don't wait for the emergency to figure it out:

• Set up VARA now (when there's no pressure)
• Make successful connections to gateways (verify everything works)
• Practice peer-to-peer with another local station
• Participate in Winlink exercises (ARES groups run regular drills)
• Have a backup plan (know multiple gateways, multiple bands)

VARA isn't glamorous and it won't win you awards. But when the internet goes down and you need to send an email reporting damage, requesting supplies, or confirming someone's safety — VARA and Winlink are what actually works.