FT8 Tips and Tricks

Here are a few tips I've picked up to help you out and maximise your FT8 station performance.

Accurate PC Time keeping

Your PC clock needs to be fairly accurate. FT8 uses alternating time slots, where everyone is either listening or transmitting. If your time is out, you'll be receiving when you should be transmitting and transmitting when you should be receiving! You don't need to be perfect, but aim for a time accuracy of less than a second.

How do you know how accurate your PC clock is?

Glad you asked. Head over to http://time.is

You should get a result like this:

If this shows more than a second you need to improve your time accuracy. If you're using a modern version of Windows head over to your time/date settings and you'll find the option to sync your time with windows servers. This should do the job. You can also find freeware software that will do this for you.

Maximise your Receiver Passband Bandwidth

The wider you open your receive passband, the more signals you will receive. How to do this depends on your radio. If you're using a radio with a DATA mode you'll need to hunt in the settings to open this up. You don't want any high or low frequency cut-offs, or filters that narrow the bandwidth. If you're running your radio in regular USB you can use the WIDTH control to open up the receive. With your FT8 software you can visually see the size of your receive bandwidth. The received signal area will show in blue. As you open up your receive you will see the blue area extend. 3000KHz is good, 4000KHz is excellent if you can go this wide.

Don't Overdrive your TX Audio

FT8 is very hard on your radios transmitter. Running your radio at full power in FT8 can be stressful and potentially even damaging. For a typical 100W transceiver you would commonly run about 20W, and as high as 50-60W if you really need it. At this power you will still be driving your radios finals much harder than if you were running 100W SSB. Make sure your transmitter/amplifier can handle full duty cycle if you run higher. Also make sure your antenna system can handle the demand. I've heard of operators melting antenna wire with FT8 that had no issues with higher power outputs in SSB.

Keeping your power down also helps you produce a clean signal. A dirty distorted TX signal will not only reduce your chances of your signal being decoded correctly, but if you splatter across the FT8 frequency you will be very unpopular!

To ensure your audio drive is optimum follow this procedure: while transmitting in FT8 start turning down your computer audio until you see your power to just start to drop on the radios power meter. Switch over to ALC and check you have no deflection or a small reading. This is the optimum level to give you full power without introducing distortion. More audio will not give you more power because you're already showing full power output. Be aware that as you change TX audio frequency (move the red TX area) you will probably need to readjust the audio level. This is because the radio does not have a linear response to all frequencies .

Try Notching out strong signals to reveal weaker stations

Using the NOTCH filter on your radio you can filter out very strong FT8 signals. This can allow you to decode weaker signals that were previously undetected.

Turn OFF any processing of received or transmitted Audio

Any processing of the sound coming IN or OUT of your radio will reduce the ability of the software to decode the signals. You want to keep the sound as pure as possible. So turn off any DNR, Noise Blanker, unintentional notch filters etc from the receive. Also turn off any processing or compression of your transmitted audio. If your radio has a data mode it should turn all these off itself.

Monitor your Signal on PSK Reporter

Using the excellent PSK Reporter website (https://pskreporter.info/pskmap.html) you can enter your callsign and see where your signal is being received. This is a very interesting and powerful website. You can use it to monitor band conditions and propagation and even compare the performance of different antennas.

Try moving your TX Frequency Band

If you're not getting a reply try moving your TX frequency across the spectrum. Not everyone is seeing the same receive passband as you. As discussed above the width of your passband and it's placement on the frequency spectrum will vary depending on your receiver and settings. Your signal could be off the bottom, or off the top of another stations passband and be invisible to them. There could also be another station transmitting on your frequency during your timeslot that you're not aware, so moving to another segment may get your signal decoded.