FT8 Etiquette: Power, ALC and Choosing a Clear Frequency

FT8 turned weak-signal operating into a mass activity, and on a busy day the waterfall on 20 metres looks like a motorway. A band that crowded works only if every operator follows a few unwritten rules, which is what FT8 etiquette is about. Nobody polices these rules; the penalty for breaking them is a splattered passband, missed decodes for everyone nearby and sometimes a hot, unhappy transmitter. This guide covers the habits that matter most: how to set transmit power, why ALC should stay quiet, how to choose a clear frequency, how to call and answer correctly, and how to finish a contact without clogging the band.

The guidance follows the WSJT-X documentation and long-standing community practice. Settings differ between radios, so treat the principles as the point and the control names as examples.

FT8 in a Nutshell

FT8 is a weak-signal digital mode from the WSJT family. As the general reference on FT8 explains, it was released in 2017 by Joe Taylor, K1JT, and Steve Franke, K9AN, and it works in 15-second cycles, typically completing a contact in about 90 seconds. Software can decode FT8 signals at signal-to-noise ratios as low as minus 20 dB in a 2500 Hz bandwidth, far below what is practical with voice or conventional CW. That sensitivity is why modest antennas and low power can produce worldwide contacts.

It also explains the first etiquette principle. FT8 is a weak-signal mode, not a low-power mode, and more power than you need helps nobody. If you are not yet set up, our guide to a WSJT-X FT8 setup that works first time walks through the basic configuration, and the official WSJT-X project page hosts the software and the user guide.

Keep the Clock Right

Every FT8 station transmits within a strict timing window, so an inaccurate clock makes you invisible to others and turns their decodes into mush. Synchronise your computer clock with a reliable time source, and check the offset displayed by your software before you transmit. The article on FT8 time sync and clock accuracy explains the tools. If a station you are working keeps showing a large time offset, a courteous note in the free text or an email later is kinder than silence.

Power: Set It With Audio, Not With the RF Knob

The most important technical habit in FT8 is the way you set power. The mode sends a steady tone-keyed signal at constant amplitude, so the transmitter works at full duty for about half of every minute. An amplifier that is happy on SSB can overheat on FT8, and a transmitter that is set to maximum is asking for trouble. A sensible approach is:

1. Put the radio into the digital or data mode. Use the data-USB setting if your radio has one, so the radio takes audio from the computer interface and not from the microphone.
2. Turn off processing. Disable speech compression, equalisation and any audio processing, because they distort a mode that depends on clean tones.
3. Set the radio’s RF power control well above the level you intend to use. Think of it as a ceiling, not the control.
4. Adjust the output level with the computer audio. Lower the transmit audio gain in the software or the operating system until the radio produces the power you want.
5. Check the result on a meter. Look at output power on the radio or a wattmeter. The aim is a clean signal at the power you chose, not the highest reading.

Why this way round? If you leave the audio high and cut the power with the RF knob, the radio’s internal level control is clipping the signal. The result is a distorted waveform that spreads sidebands across neighbouring slots. Setting power through the audio level keeps the transmitter inside its linear range.

How much power is enough? FT8 does not need much. Many operators work the world with modest power and a decent antenna, and extra power gains little once signals are above the decoding threshold, while it raises the noise for nearby stations. If you run an amplifier, keep it well within its continuous rating, because FT8 is a long-duty-cycle mode. If a contact does not answer after a few calls, the cure is almost never more power; it is a better antenna, a better time, a different band or patience.

ALC: The Needle Should Stay Quiet

ALC is the radio’s automatic level control, a protection circuit that reduces drive when the audio input is too high. On SSB, a little ALC action is normal. On FT8, it is a sign of trouble. If the ALC meter moves noticeably during transmit, you are overdriving the radio, and the signal is being flattened. The resulting distortion creates spurious products on both sides of your signal, which neighbours see as a wide, ugly block on their waterfall.

• Reduce the audio output level in the software or the operating system until the ALC reading falls to zero or almost nothing.
• Keep the radio’s power setting at a comfortable level and adjust the output with audio gain.
• Do not use the ALC meter to set power, because it indicates overdrive, not output.
• Check your signal with a second receiver or an SDR, or ask a friend. Many operators discover splatter only when someone points it out.

The PSK Reporter map, explained in our guide to PSK Reporter, is a quick way to see who hears you and how strongly, but it will not reveal splatter. For that you need to look at your signal on a waterfall and ask for reports.

Choosing a Clear Frequency

FT8 stations share the same dial frequency on each band and are separated only by their audio tone within the passband. That is why there is always a lively fight for space. A tidy operator picks a spot with a little breathing room. Practical rules:

• Look before you call. Watch the waterfall for a few cycles and find a gap, ideally with several empty tone slots on both sides.
• Use the middle of the passband. Stay away from the very bottom and top of your radio’s audio range, where filters roll off and harmonics can appear.
• Do not sit on top of someone else. Transmitting at the same audio frequency as another station in the same period ruins both decodes. If you hear someone calling CQ, leave their frequency.
• Hold your transmit frequency steady. In WSJT-X the Hold Tx Freq option keeps your tone from jumping around when you answer someone, which helps others keep track of you.
• Move if the band gets crowded. If you are interfering or being interfered with, move to a cleaner spot.
• Use split operation properly. If your radio generates spurious signals at high audio frequencies, use a split operation option in the software so the audio tone stays in the comfortable range.

Etiquette at a Glance

Calling CQ and Answering

A CQ call is an invitation, so make it easy to accept. Transmit in the period assigned to you and listen in the other, and keep the pattern consistent. If you call for a long time without an answer, take a break, check the waterfall and consider changing band or tone. Calling for ten minutes straight on a dead band occupies a slot that others might use.

Directed CQs such as a call to a specific region or programme are an etiquette signal. If the call says it is directed, answer only if you fit the description. Answering a call meant for another region wastes the caller’s time and often leaves them with a pile of unwanted replies. When several stations answer at once, the calling station chooses one, so if you are not picked, do not keep calling over the top of the contact in progress.

When you answer, be sure you decoded the callsign correctly, and send your report promptly. If your first call is not answered after a few tries, move on. The next cycle will bring another chance. When you are chasing a rare station that uses a special operating mode, see our guide to FT8 DXpedition mode, which has its own rules for Fox and Hound operation. Do not call a Fox on its own frequency, and follow the instructions.

Finishing the Contact

A standard exchange shares callsigns, a grid or other information, and signal reports, followed by confirmation. Software handles most of this, but humans can still generate noise. After you send or receive the final confirmation, stop. Do not repeat 73 over and over, do not keep calling the same station and do not leave Enable Tx on after the exchange is over. Log the contact, clear the call and make space for the next one.

If the other station does not copy the final message, resend once or twice, then move on. It is the other operator’s job to log what was received. Many stations also upload logs to online services later, so your contact is not lost.

Attended Operation and Other Habits

Automatic sequencing is a convenience, not an excuse to walk away. Check your licence conditions about unattended operation, which differ between countries, and keep your station under control while it transmits. When you leave the desk, switch transmit off. Other good habits include:

• Do not tune an antenna tuner on top of other stations. Use a dummy load or a quiet frequency.
• Keep your free text clean and short. The message length is tiny, and advertisements have no place in a crowded passband.
• Use a proper callsign, as it is transmitted, and do not use other operators’ calls.
• Watch for local interference. A noisy power supply or laptop can degrade decodes across the band.
• Rest the transmitter. If the radio runs hot, reduce power or take a break. Many problems blamed on FT8 are heat problems.

Special Cases: Busy Days and Rare Stations

Etiquette matters most when the band is busiest. During a major contest weekend or when a new country appears, the passband fills from edge to edge, and every tone slot is precious. On those days, keep calls short, avoid long chats in free text and decode carefully before you reply, because a wrong callsign wastes a whole cycle for two stations. If you see a pile of callers around a rare station, do not join in with the highest power you can muster. Wait for a gap, call only when the station is listening and follow any instructions in the operator’s announcement. A patient operator with a clean signal usually gets through sooner than one who calls constantly and splatters across the slots around the target.

Finally, remember that FT8 is a shared resource with limited bandwidth. If your station causes trouble, fix it quickly: reduce the audio level, check the ALC and ask for a report. Most interference on FT8 is accidental, and most operators are glad to help a newcomer adjust.

The Bottom Line

FT8 works because thousands of operators share a narrow slice of spectrum. Treat that space with care: set power with the audio level and keep ALC quiet, choose a clear tone and hold it, call politely, answer only calls meant for you, finish cleanly and stay at the desk while you transmit. These habits cost nothing, keep your signal clean and make the band better for everyone, including you.

Frequently Asked Questions

How much power should I use for FT8?

Use the lowest power that gives reliable decodes. Many contacts are made with modest power, and extra watts can distort your signal and annoy neighbours. Never exceed your amplifier’s continuous rating.

Why should ALC show nothing on FT8?

ALC action means the audio drive is too high and the signal is being clipped, which creates splatter. Reduce the audio level until the ALC needle stays at rest.

Should I set power with the radio’s power knob?

Prefer to set it with the computer audio level. Using the RF knob to cut a hot signal leaves the audio overdriving the radio and creates distortion.

How do I choose a clear frequency?

Watch the waterfall for a few cycles, pick a gap away from active stations and away from the extreme edges of the passband, and use the hold option to keep your tone steady.

Can I leave FT8 running while I am away?

Check your licence rules on unattended operation. In general, stay at the station while it transmits and turn Enable Tx off when you leave.

What should I do if my clock is out?

Synchronise it with an accurate time source before you transmit. A clock error of even a second can stop others from decoding you.