A WSJT-X and FT8 Setup That Works the First Time
FT8 has a reputation for being easy to operate and awkward to install. The operating part is fair — once it runs, the software does most of the work. The installation part is fair too, but the difficulties are predictable, and almost all of them come down to three things: audio, control and time.
Get those three right and the rest is configuration detail.
Understand What Is Actually Connected
Before touching a setting, be clear about the three separate connections between computer and radio. Confusing them is the root of most setup problems.
- Receive audio — from radio to computer, so the software can hear and decode.
- Transmit audio — from computer to radio, so the software can generate the signal.
- Control — a separate data path that sets frequency, mode, and keys the transmitter.
On a modern radio with a built-in sound interface all three may travel over a single USB cable, but they remain logically distinct and are configured separately. On an older radio they are physically separate: an external interface for audio, a serial connection for control.
When something does not work, identify which of the three is at fault before changing anything. Decoding failures are audio problems. Failure to transmit is usually control. Wrong frequency reported is control.
Time Synchronisation Is Not Optional
FT8 uses fixed transmission periods, and decoding depends on both stations agreeing on when those periods start. If your clock drifts by more than a fraction of a second, decoding degrades. Drift further and it stops entirely.
This is the single most common reason a newly installed system decodes nothing while the operator concludes the audio is wrong.
The fix is to run proper network time synchronisation and verify it is actually working rather than assuming the operating system handles it. Many default configurations update infrequently and tolerate more drift than digital modes do. A dedicated time-sync utility is worth the trouble on any machine used for digital operation.
A useful diagnostic: if the software shows decodes with consistently large time offsets, the clock is the problem. If it shows no decodes at all and the waterfall is blank, the problem is audio.
Audio Levels: The Range That Matters
Two level settings cause most of the difficulty, and they fail in opposite directions.
Receive level should put the noise floor somewhere in the lower portion of the meter with the band quiet — enough signal to work with, far from the top. Too low and weak signals sit below the decoder’s reach. Too high and the input clips, which destroys decoding even though the waterfall looks impressively busy. A waterfall that is bright everywhere is a symptom, not an achievement.
Transmit level is where the real damage happens. FT8 is a constant-envelope mode and must be driven cleanly. Overdriving produces splatter across a wide portion of the band, which other operators will notice and mention.
The correct procedure is to reduce audio drive until the transmitter’s ALC action is at or near zero, then check output power. If you are running a radio that reports ALC, any significant ALC deflection on a digital mode means the audio is too hot. Set the power with the radio’s own power control, not by pushing more audio.
Running at reduced power is also sensible. Most radios are not designed for extended full-power transmission at a hundred percent duty cycle, and FT8 transmissions are exactly that.
CAT Control Settings
Control configuration is mostly a matter of matching parameters exactly:
| Setting | What to check |
|---|---|
| Port | The correct device; radios often present two, only one of which carries control |
| Baud rate | Must match the radio’s own menu setting exactly |
| Data bits, stop bits, parity | Match the radio’s documentation, not a guess |
| Handshake | Frequently the cause of “port opens but nothing happens” |
| PTT method | CAT, RTS, DTR or VOX — pick one and be consistent |
Test the control path with the software’s own test function before going further. A control link that reads the frequency correctly but will not key the transmitter usually has a PTT method mismatch.
If you also run logging software, remember that two programs cannot own the same serial port simultaneously. A rig control layer such as Hamlib or a shared control server exists precisely to arbitrate this, and setting it up early saves a great deal of confusion later.
Operating Practice Worth Adopting
Once the system works, a few habits separate operators who enjoy the mode from those who irritate everyone else:
- Listen before transmitting. Watch a few cycles to see what the band is doing.
- Do not transmit on top of an ongoing exchange. The waterfall shows where the space is.
- Complete the sequence. Abandoning a partial exchange leaves the other station guessing whether to log it.
- Use the lowest power that works. The mode decodes deep into the noise; excessive power helps nobody and creates problems for nearby stations.
- Check the correct sub-band for your region. Frequencies and band plans vary by IARU region and country, so take them from your national society’s current band plan rather than from an article or from memory.
When It Still Does Not Work
A short triage list, in order:
- Waterfall blank → receive audio not reaching the software. Check device selection first, cabling second.
- Waterfall active, no decodes → clock synchronisation, almost always.
- Decodes present, transmit does nothing → PTT method or port conflict.
- Transmits but no power out → audio level too low, or radio in the wrong mode.
- Reports of splatter → audio level far too high; reduce until ALC reads zero.
- Works, then stops after a while → USB device renumbering or a sleeping port. Disable power management on the port.
Frequently Asked Questions
Do I need a special interface?
If the radio has a built-in USB sound device and control, no. Older radios need an external interface providing isolated audio and a control connection. Isolation matters — it prevents ground loops that inject noise.
Why do I decode stations that never answer me?
Weak-signal modes decode far below the level at which a station is workable both ways, and paths are not symmetrical. Reverse beacon data showing where your own signal lands is more informative than what you can hear.
How much power should I run?
Less than you think. The mode is designed for weak signals. Many operators work the world with output measured in low tens of watts, and high power on a crowded band mostly creates problems for others.
Can I run FT8 and logging software at the same time?
Yes, but they must not both claim the serial port directly. Use a shared rig control layer, or let one program control the radio and pass data to the other.
Why does my transmission start late?
Clock drift, or the software waiting on a slow control response. Fix time synchronisation first; if the offset is correct, look at CAT timing.
Is FT8 real operating?
It is a different kind of operating — less conversation, more signal processing. Whether that appeals is a matter of taste. What is not in dispute is that it works when nothing else will, which is why it dominates during poor conditions.
The Bottom Line
Three things decide whether a WSJT-X installation works: correct audio routing at sane levels, a control link with matching parameters, and a clock that is genuinely synchronised. Nearly every reported problem is one of those three wearing a disguise.
Set them carefully once and the system will run for years with no attention.
More guides on the blog index, including how propagation decides which band to be on. The authoritative reference is the WSJT-X user guide, and band plans should come from your national society, such as the IARU Region 1 band plan.