FT8 is a weak-signal digital mode developed by Nobel Prize winning physicist Joe Taylor (K1JT) and Steve Franke (K9AN). It has become the most popular HF digital mode in amateur radio, and for good reason — it works with modest equipment, modest antennas, and even modest band conditions. Contacts that would be impossible on SSB voice are routine on FT8.
This page covers everything you need to get from zero to making your first FT8 contact.
What Makes FT8 Different
FT8 operates on a fixed 15-second transmission cycle. Every exchange is highly structured — callsigns, signal reports, and grid squares are exchanged in a defined sequence, and the software handles most of it automatically. Transmissions are only 15 seconds long and occupy just 50 Hz of bandwidth, which means dozens of stations can operate simultaneously on a single frequency.
The tradeoff is that FT8 is not a conversational mode. You won’t be chatting about your antenna or the weather. It is purpose-built for making contacts efficiently under difficult conditions.
What You Need
Radio: Any HF transceiver capable of SSB will work. The IC-718 and similar all-band radios are ideal. Keep power to 25–50W or less — FT8 is a continuous duty cycle mode and running full power will stress your finals over time.
Computer: Any reasonably modern PC running Windows or Linux. The software is lightweight.
Audio interface: A dedicated sound card interface is the cleanest way to connect your radio to your PC for FT8. Two popular options at different price points:
SignaLink USB — A plug-and-play USB audio interface made by Tigertronics. Includes a built-in adjustable transmit level control (the TX knob) which makes setting audio levels straightforward. Connects via a radio-specific cable matched to your rig’s accessory or mic/speaker ports. Works on Windows and Linux without drivers. A reliable and widely used choice — signalink.com
DigiRig Mobile — A compact and affordable USB sound card interface from digirig.net. Smaller than the SignaLink and designed for portable use, but equally capable for base station operation. Also uses radio-specific cables and works driver-free on Windows and Linux. A good option if you want something compact or budget-friendly.
Both interfaces appear in WSJT-X’s Audio settings as USB audio devices. The setup process is identical for either — select the interface as both your Input and Output device in the Audio tab.
Accurate time: This is critical. FT8 timing is synchronized to the second. Your PC clock must be accurate to within approximately 1 second. Use an internet time sync tool — on Windows this is built in, on Linux use chrony or ntpd.
Software — WSJT-X
WSJT-X is the primary software for FT8. It is free, open source, and available for Windows, Linux, and macOS.
Download it at physics.princeton.edu/pulsar/k1jt/wsjtx.html
Installing on Windows:
Download the installer (.exe), run it, and follow the prompts. WSJT-X will install to Program Files and create a desktop shortcut.
Installing on Linux:
On Debian/Ubuntu-based systems:
Download the .deb package from the WSJT-X website and install with:
sudo dpkg -i wsjtx_*.deb
sudo apt-get install -f
On other distributions, use the tarball or check if your distro’s package manager has a current version.
Configuring WSJT-X
Open WSJT-X and go to File → Settings.
General tab:
Enter your callsign and grid square. Your grid square is a 4 or 6 character locator — find yours at qthlocator.free.fr or maidenhead.thomasv.nl. For WZ4JM in Ocala that is EL89.
Radio tab:
Select your radio type from the Rig dropdown. If your radio supports CAT control via USB, select the correct COM port (Windows) or /dev/ttyUSB0 (Linux) and set the baud rate to match your radio’s CAT settings. For the IC-718 with a SignaLink, set PTT method to VOX — the SignaLink handles PTT automatically via VOX internally. With a DigiRig, set PTT method to CAT or RTS depending on which DigiRig cable you are using — check the digirig.net documentation for your specific radio cable.
Audio tab:
Set the Soundcard Input to your audio interface (the CM108AH or equivalent will appear here as a USB audio device). Set Output to the same device. Leave the channels set to Mono unless your interface requires stereo.
Reporting tab:
Check “Enable PSK Reporter spotting” to upload your spots to pskreporter.info. This lets you see who is hearing you in real time, which is extremely useful for evaluating your signal and antenna.
Audio Levels — Getting This Right
Audio levels are the most common setup problem and the one that causes the most frustration. Too low and nobody decodes you. Too high and you create a distorted, wide signal that will draw complaints.
Receive level: The WSJT-X waterfall should show signals as visible traces without the background noise floor being too bright. Aim for a noise floor around –20 to –25 dB on the band activity window. Adjust your radio’s audio output or the input level on your PC until this looks right.
Transmit level: Set your radio to USB mode and watch the ALC meter while transmitting. The ALC should barely move — if it is pegging, you are overdriving the radio and your signal will be distorted. Start with your PC audio output at around 50% and your radio’s mic gain low, then increase slowly while watching ALC. A clean FT8 signal occupies about 50 Hz. A distorted one can splatter across several kHz and will be visible as a wide smear on other operators’ waterfalls.
A good target is around 25–40W output on a 100W radio for FT8. This keeps duty cycle stress manageable and your signal clean.
Common FT8 Frequencies
These are the standard dial frequencies — set your radio to USB and WSJT-X tunes within the audio passband:
160m: 1.840 MHz
80m: 3.573 MHz
40m: 7.074 MHz
20m: 14.074 MHz
17m: 18.100 MHz
15m: 21.074 MHz
10m: 28.074 MHz
6m: 50.313 MHz
20m is the best starting point. It is active around the clock and supports both domestic and DX contacts.
Making Your First Contact
Set your radio to 14.074 MHz USB. In WSJT-X select the FT8 mode and make sure your time is synced. You will start seeing decoded signals appear in the band activity window within the first 15-second cycle.
To call CQ, click an empty spot on the waterfall to set your transmit frequency, check the “Enable Tx” box, and click “Tune” briefly to confirm your audio levels are correct, then click “Tx even/1st” or “Tx odd/2nd” and hit “Enable Tx.” WSJT-X will start calling CQ automatically on the next available cycle.
When a station responds to your CQ, WSJT-X will handle the exchange automatically if you have “Auto Seq” enabled. The sequence goes: CQ → response with grid → signal report → RR73 → 73. The whole contact takes about 90 seconds.
To call another station rather than CQ, double-click their callsign in the band activity window. WSJT-X will set up the contact sequence and wait for the right moment to transmit.
Performance Observations
A few things learned from operating FT8 on the IC-718 with a wire antenna:
20m is king. The 20m band on FT8 is active nearly 24 hours a day and produces reliable DX contacts even with a simple dipole at modest heights.
Time sync is non-negotiable. If your clock is off by more than a second or two, your decodes drop dramatically and other stations may not decode you at all. On Windows, force a time sync before each session. On Linux, make sure chrony is running and synchronized.
Lower power works. FT8 is designed for weak signal work. Running 25W will get you almost everything 100W will, with less stress on your radio and a cleaner signal on the band.
Watch the ALC. A clean signal gets more responses than a high-power dirty one. If you’re not getting replies, check your audio chain before increasing power.
PSK Reporter is your friend. After calling CQ, check pskreporter.info to see where your signal is being heard. It is one of the most useful tools for evaluating antenna performance and propagation in real time.
Further Reading
WSJT-X User Guide — physics.princeton.edu/pulsar/k1jt/wsjtx-doc/wsjtx-main-2.6.0.html
PSK Reporter — pskreporter.info
DX Maps — dxmaps.com — real time propagation visualization
HamSCI — hamsci.org — citizen science projects using FT8 and WSPR data
73 de WZ4JM — happy to answer questions via the Contact page if you get stuck getting set up.