Radar Indicator, CS-55ACE, ASD Surface-Search, WWII US Navy
The indicator is a CS-55ACE indicator for a WW2 US Navy Type ASD surface-search radar system. The ASD was the first effective American microwave search radar, and was used in aircraft such as the US Navy's Patrol Bomber Lockheed PV-1 Ventura, PV-2 Harpoon, and Grumman TBF Avenger.
Researching the internet reveals that Type ASD X-band airborne search radar used this indicator as a B-scope (range vs bearing) in US Navy patrol aircraft to detect ships and surfaced submarines. It was also used for navigation and bombing in conjunction with the AN/APQ-5 low level radar bombsight, as well as for radar sets AN/APS-3 and - 4.
The scope face itself is 4 1/2". Complete face with controls is 5 1/2" rectangular and 15" deep. Controls on the front are Focus, Intensity, VBC (Vertical), HBC (Horizontal) and Brilliance.