sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 862549F9 sudo nano /etc/apt/sources.list
Add the following to the end of the sources.list file:
deb http://ppa.launchpad.net/ki7mt/wsjtx-next/ubuntu trusty main
Ctrl-X to save and exit.
sudo apt-get update # important sudo apt-get install wsjtx
Then just run from the command line the first time to see any errors, after that run it from the Ham Radio applications menu.
I'm running a SignaLink USB interface and controlling an FT-817 via Hamlib. It correctly found the audio interface on first run.
Here it is sitting on top of the PC tower it has replaced.