WSJT‑X Setup Guide – FT8 & FT4 Configuration Made Easy

This guide provides a basic walkthrough for installing and configuring WSJT-X on a Windows PC, including the installation of the required device drivers, interface software and time-synchronisation tools. It assumes you are reasonably familiar with installing software on your computer and navigating Windows features such as Device Manager.

The setup process for JS8Call is very similar, so this guide can also be used as a general reference. However, unlike FT8 and FT4, JS8Call does not require an accurately synchronised PC clock.

I have based this document around configuring our Digimode-4 interface (below) which is available from our Icom, Kenwood, Xiegu, Yaesu, Alinco and Ten-Tec Shop pages.

These drivers allow your PC to communicate with the radio via the CAT port so that WSJT-X can control the radio's frequency and operating mode. They can also be used to provide a dedicated PTT (Push-To-Talk) control signal to switch the radio between transmit and receive. It is worth noting that many radios also support PTT control via CAT commands.

We do recommend using hardware PTT rather than CAT PTT wherever possible. There are two main reasons for this:

Some radios require the Data/Accessory port PTT line to be activated before they will accept audio from the external data input and mute the microphone.
Hardware PTT is generally more reliable in environments where RF interference may be present. If RF is picked up on the cables between the PC and transceiver, CAT commands can occasionally be corrupted. This can result in the radio entering transmit but not receiving the command to return to receive. Using the COM port RTS line for PTT helps avoid this potential issue.

Our interfaces use the highly reliable FTDI chipset. Depending on your operating system, the required drivers may not already be installed. The installation procedure differs slightly between Windows, macOS, and Linux; however, this guide assumes you are using Windows.

You can download the latest FTDI drivers here: FTDI Drivers

For Windows users, the easiest installation method is to locate the Windows (Desktop) entry on the FTDI drivers page. In the Comments column, click the "Setup Executable" link, download the installer, and run it.

The FTDI VCP Driver area is shown below with the setup executable highighed.

This will download the driver to your Downloads folder. It will begin CDMxxxxx_Setup.zip. Inside the .zip file is a single (safe) executable. Just follow the instruction to complete the installation on your PC.

Connect your Digimode-4 interface to your PC

You can now connect your Digimode-4 Interface to a spare USB port on your PC.

Windows may play its usual notification sounds while it detects and registers the various devices contained within the interface. The Digimode-4 includes an internal USB hub, allowing both the FTDI USB COM Port and the built-in USB Sound Card to appear as separate devices on your PC.

The USB hub chipset and the C-Media USB Sound Card use generic drivers that are already included with Windows and most other operating systems, so no additional driver installation should be required.

In the Windows taskbar search box, type "Device Manager" and launch the Device Manager application from the search results.

Identify the USB Audio Device Name

First, expand the "Sound, Video and Game Controllers" section. As shown in the image below, you should see a device called "USB Audio Device" listed.

Make a note of the full USB Audio Device name (it may be given a numerical prefix), as you will need to select it later when configuring the audio settings in WSJT-X.

Identify the COM Port Number

Whilst still in Device Manager, expand the "Ports (COM & LPT)" section. You should now see a new entry called "USB Serial Port (COMx)".

Make a note of the COM port number, as you will need this when configuring the CAT settings in WSJT-X. In the example shown below, the interface has been assigned COM3.

If you have several USB serial devices connected and are unsure which one belongs to the Digimode-4 interface, simply unplug the interface and watch the list refresh. The COM port entry that disappears is the one associated with the Digimode-4. Reconnect the interface and confirm that the same entry reappears.

That's all there is to the PC and driver setup. With the Digimode-4 interface connected and recognised by Windows, and the COM port number noted down, we're ready to move on to installing and configuring WSJT‑X.

Let's get WSJT-X installed and set up

Download the install WSJT-X

WSJT-X can be downloaded from the WSJT-X Download Page

The download page provides installation packages for Windows, macOS, and various Linux distributions. For the purposes of this guide, I will be covering the Windows installation.

Once the download has completed, run the WSJT-X installation .exe file. Windows will prompt you to confirm that you are happy for the installer to make changes to your device. Click Yes to continue.

The WSJT-X Setup Wizard will then open:

Click Next >
Read and accept the licence agreement by clicking I Agree
Accept the default system path settings and choose whether you would like a desktop icon to be created
Click Next >
Accept the default installation folder or choose an alternative location
Click Next >
Accept the default Start Menu folder settings
Click Install

On a modern PC, the installation typically takes less than a minute. Once the installation is complete, click Next > and then Finish. You can leave the option ticked to launch WSJT-X immediately.

Initial WSJT-X Configuration

With WSJT-X running, click File → Settings to open the configuration window.

Start with the General tab (As shown below)

The two most important settings here are:

Callsign – Enter your amateur radio callsign.
Grid Locator – Enter your Maidenhead grid square.

Once entered, click OK to save the settings.

Configure CAT Control and PTT
We will now move on to configuring the radio, CAT control and PTT settings.

Click on the Radio tab within the Settings window. In the example below, I am configuring WSJT-X for an Icom IC-718. Some of the settings required will need to match those configured in your radio's menu system.

If your interface does not support CAT control, simply set Rig: to "None" from the drop-down list and ignore the settings in the CAT Control section.

CAT Control Setup

Select your radio model from the Rig: drop-down list. It is important that you choose the correct radio model.
In the CAT Control section, set Serial Port: to the COM port number you noted earlier in Device Manager.
Set Baud Rate: to match the CAT baud rate configured in your radio's menu system.
Important: If your radio does not support CAT control, or you are using an audio-only interface, you must set Rig: to "None". This will hide the CAT control settings and allow you to continue configuring WSJT-X without CAT control.

PTT Configuration

Next we configure the PTT Method section. Our Digimode-4 Interface supports both CAT PTT (where supported by the radio) and COM Port RTS keying. We generally recommend using RTS PTT for maximum reliability.

If your interface does not support CAT control or RTS keying, select VOX instead.

Set PTT Method: to RTS.
Set Port: to the same COM port number used for CAT control.

Your settings should look similar to those shown in the screen capture below, where the Digimode-4 interface has been configured for an Icom IC-718. In this example, COM3 is being used and the radio's CAT baud rate is set to 9600.

You will notice two buttons at the bottom of the Radio tab labelled "Test CAT" and "Test PTT".
Before WSJT-X has successfully verified the CAT connection, the "Test PTT" button will remain greyed out.

Once you have entered all of the CAT settings, click "Test CAT". WSJT-X will attempt to communicate with the radio and read its current frequency. If the test is successful, the "Test CAT" button will turn green (as shown below) and the radio's frequency will be displayed in the main WSJT-X status window.

If the button does not turn green, double-check that the correct Rig, COM Port, and Baud Rate have been selected and that CAT control is enabled in your radio's menu settings.

Once the CAT test has passed, the "Test PTT" button will become active.

The "Test PTT" button is simply a toggle. Pressing it once will key the transmitter and the button will turn red to indicate that PTT is active. Pressing it again will release PTT and return the radio to receive.

When using RTS PTT, you should hear the radio switch into transmit and then back into receive as you click the button on and off. This confirms that WSJT-X is correctly controlling the PTT line through the Digimode-4 interface.

At this point, the CAT and PTT configuration is complete.

Don't forget to click "OK" at the bottom of the Settings window to save your changes.

If any of the settings are incorrect, such as:

The wrong radio model selected
An incorrect COM port number
A CAT baud rate mismatch
CAT control not enabled on the radio
The interface connected to the wrong socket on the radio

Then WSJT-X may display an error message similar to the one shown below.

If this happens, work back through the settings and verify that the radio model, COM port number, baud rate, and other CAT settings match those configured in your radio and shown in Windows Device Manager. Also check that all cables are connected to the correct ports on both the interface and the transceiver.

Configure WSJT-X Audio Devices

With the Radio tab configured and tested, we can now move on to the audio settings.

Click on the Audio tab within the Settings window as shown below. This is where we tell WSJT-X which sound card to use for receiving audio from the radio and sending audio back to it during transmissions.

For both Input and Output, select the USB Audio Device that you identified earlier in Device Manager.

This is the USB sound card built into the Digimode-4 interface.

Input: Select USB Audio Device
Output: Select USB Audio Device

Your settings should look similar to those shown in the screen capture below.

If you have multiple sound cards connected to your PC and are unsure which one belongs to the Digimode-4 interface, disconnect the interface and note which audio device disappears from the list. Reconnect the interface and confirm that the device reappears.

Once you have selected the correct audio devices, click Apply or OK to save the settings.

At this point, the basic WSJT-X configuration is complete and we can move on to verifying that audio is being received correctly from the radio.

Audio Settings and Levels
For the Digimode-4 Interface, all receive and transmit audio levels are adjusted using a combination of controls within Windows and WSJT-X.

We will start with the receive audio setup, as this is the simplest to configure.

Disable Microphone AGC

The first step is to ensure that the AGC (Automatic Gain Control) function for the USB Audio Device is disabled. If enabled, AGC can cause fluctuating audio levels, overload conditions and make it difficult to correctly set up WSJT-X.

From the Windows Sound Control Panel, open the properties for the USB Audio Device recording input.

Navigate to the Custom tab and ensure that AGC is NOT enabled, as shown in the image below.

Once AGC has been disabled, we can move on to setting the receive audio level correctly within WSJT-X.

Disable "Listen to this Device"

Another setting worth checking is that "Listen to this device" is not enabled for the USB Audio Device microphone input.

From the Windows Sound Control Panel, open the properties for the USB Audio Device recording input and select the Listen tab. Make sure "Listen to this device" is unchecked, as shown in the image below.

If this option is enabled, Windows will route the receive audio back to your PC speakers or sound card, which can result in unwanted audio feedback, distorted audio levels and other confusing issues when setting up WSJT-X.

Setting the Receive Audio Level

Next, tune your radio to an active FT8 frequency, such as 7.074 MHz on the 40m band.

Whilst monitoring the WSJT-X main screen, open the USB Audio Device Microphone properties in Windows and select the Levels tab as in the image below.

Adjust the microphone level slider until the Rx Level bar graph in WSJT-X is approximately two thirds scale and is green. This provides a good starting point for reliable decoding without overdriving the input.

Don't worry about getting the level exactly right at this stage. As you become more familiar with WSJT-X and your radio, you can further optimise these settings to achieve the best performance.

Your receive audio level should look similar to the example shown below.

Setting the Transmit Audio Level

We will now set up the transmit audio level, and there are a few important points to bear in mind.

The audio level sent from the interface to the radio directly affects your transmit power. Digital modes such as FT8 and FT4 use multiple simultaneous tones, so it is important not to overdrive the transmitter.

Attempting to generate excessive power can drive your radio's power amplifier into compression, producing a distorted signal that is actually harder for other stations to decode.

An overdriven signal will also become unnecessarily wide, causing interference to adjacent operators and making you unpopular with others on the band. The aim is therefore to keep the transmitter operating linearly and to avoid excessive ALC (Automatic Level Control) action.

As a general rule, I tend to operate at powers below 40 Watts, which works very well for most contacts. We have also created a separate page covering transmit power and ALC optimisation, which you may find useful.

The transmit audio level can be adjusted in two places:

The USB Audio Device playback level within the Windows Sound Control Panel.
The Pwr slider within WSJT-X.

Both controls affect the audio level being sent to the radio and therefore influence the transmitter output power.

My recommendation is to set the USB Audio Device playback level to around 50% as a starting point and then use the Pwr slider in WSJT-X for day-to-day power adjustments. This makes it much easier to control your output power without repeatedly opening the Windows audio settings.

In the next step, we will use the Tune button in WSJT-X to generate a steady carrier and set the transmit audio level correctly.

Final Audio Level Adjustment

You have two options for controlling your transmit power:

Set the USB Audio Device playback level in the Windows Sound Control Panel to 100% and then adjust your transmit power using the "Pwr" slider on the WSJT-X main screen.
Set the WSJT-X "Pwr" slider to maximum and adjust your transmit power using the USB Audio Device playback level in the Windows Sound Control Panel.

My preference is the first option, as it allows transmit power to be adjusted directly from within WSJT-X without having to open the Windows sound settings.

Setting a Clean Transmit Level

My final tip is how to set your transmit power while minimising the risk of overdriving your transmitter's power amplifier.

Start by setting the radio's RF power control to a sensible level, for example 50% of maximum power.

Then, whilst monitoring the radio's ALC meter, transmit a signal and slowly increase the audio level using the WSJT-X "Pwr" slider until the ALC is just beginning to operate. Once you reach this point, reduce the audio level by approximately 20%.

This should leave the transmitter operating comfortably within its linear range and produce a clean signal.

If the resulting output power is not where you want it to be, adjust the radio's RF power setting and repeat the process above.

Following these steps should give you a fully functioning WSJT-X installation with reliable CAT control, PTT operation and properly adjusted audio levels.

We have written a detailed Transmission optimisation and ALC guide here.

What's Next?

To get the most from WSJT-X, I highly recommend reading the official WSJT-X User Guide

Modes such as FT8 and FT4 have their own operating conventions and etiquette. The protocol is designed to exchange the minimum amount of information required to complete a QSO, so many common messages and responses are predefined within the FT8 data structure.

Before making your first contacts, I would recommend spending some time simply monitoring activity on the bands. Watching a few FT8 QSOs from start to finish is an excellent way to understand the sequence of exchanges and become familiar with how the software operates in practice.

NTP Setup

Anchor 1

FTDI Drivers

Connecting the Digimode 4

Identifying Devices

WSJT-X setup

Configure CAT/PTT

Audio Settings

Rx AF settings

Tx Audio Settings

Fine settings

Whats next

Welcome to ham-interfaces.com

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WSJT‑X Setup Guide – FT8 & FT4 Configuration Made Easy

On This Page

Ensuring your PC Clock is aligned to NTP

Installing the FTDI COM Port drivers

Connect your Digimode-4 interface to your PC

Identify the USB Audio and COM Port Device Names

Installing and setting up WSJT-X

Setting up Receive Audio Levels

Setting up Transmit Audio Levels

Fine Settings for Clean Transmission