Radio Loudspeaker LS-3, Signal Corps US Army S2 Tracker called a throat

called a throat

and shutter speed is adjustable from 125 to 500

The observer held the indicator about two feet from his eye

Ledge diameter

Radio Loudspeaker LS-3, Signal Corps US Army S2 Tracker called a throatThe LS 3 Loudspeaker was used during WWII with a variety of US Army Signal Corps receivers, such as the BC 312 and BC 348, and used on into the 1950's. Would have been used in ground installations (as opposed to use within aircraft, where headphones would likely have been the preferred method of rendering audio to the crew). See the photo of the interior. It appears that the components may be original and untouched. We have not tested it, so selling