Hi. im on ubuntu 16.04 LTS on an I3-4005u laptop.
here is what i did: https://wiki.myriadrf.org/Lime_Suite (STEP 2.1) is all i had to do
it adds PPA for myriad (Limesuite and Soapy) and do not follow this guide for GQRX on ubuntu as it will break stuff. http://gqrx.dk/download/install-ubuntu <<<< Do not do this as of this writing.
at least i dont recommend it,
but everything from the myriad setup should give you latest Limesuite. mine is 18.04
to get gqrx working i just got the 2.11.4 appimage and you download it and extract it or just double click on it. it opens up with good device selection i think
My experience with separate PPAs for the LimeSDR stuff is mismatched versions of things in gnuradio so you end up with a version that can use the LimeSDR, and a version that can use your other SDRs. Building everything from source and using Docker to put it in its own container was the only way I could keep things sane.