When the Operator wants multiple applications to receive decodes from WSJT-X, the applications must be configured with settings as follows:


Multicast UDP support in WSJT-X provides the ability for two or more applications running on the same PC to be able to interact with WSJT-X using the same UDP IP Address and Port.

In order to enable multicast UDP in WSJT-X, the following configuration settings need to be made in the UDP Server group of controls on the Reporting tab in the WSJT-X Settings dialog:

The UDP Server: address field value needs to be a valid IP address in the through address range or the through address range.  The default value of is suitable.

The default UDP Server port number: field value of 2237 is suitable.

Select the loopback_n option from the Outgoing interfaces: drop down listbox. The number suffix may be different depending upon how many real and/or virtual Ethernet interfaces are installed on your system.
You might want to select all of them

The value of 1 in the Multicast TTL: field is suitable.

Ensure that the Accept UDP requests, Notify on accepted UDP request and Accepted UDP request restores window checkboxes are ticked.

HRD Logbook

The multicast UDP support in HRD Alert is enabled by  the following settings in the HRD Alert Options dialog:

Enter the same Multicast IP Address and Port number as specified and tick the Enable Multicast Address checkbox.


Multicast UDP support is provided in later versions of JTAlert and the multicast address and port number are automatically determined by JTAlert when it is started.   I suspect JTAlert reads the values from the WSJT-X configuration settings file.


Grid Tracker

Multicast UDP support is provided in Grid Tracker.
Go to Settings > General and enter the milticast IP Address (in this case and port 2237)
Enable the Multicast checkbox.

Disable forward UDP Messages!

Restart Applications

After making these changes to these applications it is recommended that they all be shut down and restarted in the following order:

  1. HRD Logbook
  3. JTAlert or other applications

Note: these applications must all be running on the same PC.

There is a video available on our Youtube channel also

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