Marconi came back to the USA after WW II as GEC-Marconi. For awhile
(until, ablout 1996) the Company was GEC-Marconi Avionics (Norcross, GA)and
later just Marconi Avionics. They moved to the Dallas area and I have no
idea if they exist any longer.

Canadian Marconi existed for years with the Canadian Government and Military
as their giggest customer. They licensed the RCA AR-88 receiver
and some of the RCA/Marconi gear until well after WWII.

GEC (UK GE) still runs Marconi in the UK and Marconi Avionics was a unit.

You might consult books such as Shortwave Receivers: Past and Present by
Fred Osterman for more company info.

Dave Thompson, K4JRB