Looking at aninstall of a Classic Skyview (including EMS, ADS-B, ADHARS, Transponder, etc) and the gent put all the grounds together into one connector. Is this a recommended procedure or called for in the manual?
It is common to ground everything at the firewall using a forest of tabs (FoT). That said, best practice is to ground the audio/radio devices together, then to the FoT.