Hi Chris,
As Lee has implied, noise can be caused when also running another device (a less than fully charged tablet is a favourite) from the same Anker charger as your Rosetta. For this reason we recommend running the PilotAware from its own dedicated supply even where the adapter has 2 outlets.
Also I don’t understand why you would be running a separate GPS for your iPad as PAW automatically provides position data to your Nav Device and what do you mean by ‘Aware GPS’?
Increasing the squelch level on your radio only sets a threshold for incoming radio signals - specifically to counter noise. Any signal which is too weak (below the noise level) simply won’t be heard, but there is no effect on stronger (more local) signals. It also has no effect whatever on radio transmission. As long as you can still hear other aircraft/Ground Stations, all will be fine, though it is of course still worth trying to find and resolve the source of the noise if we can.
Other common causes worth looking for are things like poor electrical connections, bad earth continuity, and cables carrying radio and other electronic data running close alongside each other.
Keep us posted.
Regards
Peter