Key Points
- FT8 stations transmit for about 13 seconds in each 15-second slot, so your computer clock must be right to within about a second.
- You need an HF radio that can transmit on upper sideband or a data mode, the free WSJT-X program, and a way to connect the two.
- Start at a standard dial frequency such as 14.074 MHz on 20 meters or 7.074 MHz on 40 meters.
- 20 to 50 watts is plenty. Set the audio so the radio’s ALC shows little or no movement.
- A contact takes about a minute and a half, and your log can go to Logbook of The World.
Tune to 14.074 MHz on almost any day and you’ll hear a warbling chorus of tones. That’s FT8, the most popular digital mode on HF. It was written by Joe Taylor, K1JT, and Steve Franke, K9AN, and first released in 2017 as part of the free WSJT-X program. It lets modest stations make contacts in conditions where voice would be hopeless.
How It Works
FT8 runs on a strict timetable. Everyone transmits for about 13 seconds inside a 15-second slot, then listens for the next 15. Each signal is only about 50 Hz wide, so dozens of contacts share a 3 kHz slice of the band at once. The software decodes every signal it can hear in the slot and lists them on screen.
The messages are tiny: callsigns, a grid square, a signal report and a confirmation. You won’t be chatting about the weather. In exchange you get a mode that decodes signals far too weak to hear, often well below the noise.
What You Need
An HF radio that can transmit on upper sideband (USB) or a data mode. A computer running WSJT-X, which is free for Windows, Mac and Linux. A way to connect the two: many newer radios have a USB sound card built in, so one USB cable does it all; older radios need an interface such as a SignaLink or Digirig. And an accurate clock.
The clock matters more than anything else. Because every station works to the same 15-second schedule, your computer’s time needs to be correct to within about a second, and closer is better. Windows’ built-in time sync often drifts; a small time-sync program that checks more often solves most “why can’t I decode anything” problems.
Setting Up
Put the radio on USB (or its data mode) at a standard FT8 dial frequency, such as 14.074 MHz on 20 meters or 7.074 MHz on 40 meters. Our band plans page lists them all. Tell WSJT-X which radio you have so it can control it, choose the right sound card for input and output, and enter your callsign and 4-character grid square.
Keep the power sensible. 20 to 50 watts is plenty on FT8, and many radios run hot at full power in a continuous digital mode. Set the audio level so the radio’s ALC shows little or no movement. Overdriving makes a splattery signal that wipes out other stations.
How a Contact Goes
A typical exchange takes about a minute and a half. Station 1 calls CQ with a callsign and grid. You answer with your call and grid. They send you a signal report. You send back an “R” and a report for them, meaning “roger, and here’s yours.” They send RR73, meaning “all received, best wishes.” You send 73, and the contact is complete. WSJT-X queues each message for you; you mostly just double-click the station you want to work.
Listen for a few minutes before you transmit. Pick a clear spot in the waterfall for your own signal rather than transmitting on top of someone. And don’t worry about perfection: everyone on FT8 started by watching the screen scroll and wondering what it all meant.
After the Contact
WSJT-X keeps a log file you can import into your logging program. Upload it to Logbook of The World (LoTW) and many of your contacts will confirm automatically, which counts toward awards like Worked All States and DXCC.
Once you’re comfortable, you’ll find FT8 is a great way to learn propagation. Watch which bands open to which parts of the world and at what time of day, all from a chair in your shack.