What I saw was merely a retrospective about early televised science fiction in general. The program showed that clip to illustrate the "frugal" budget. I have not found the clip itself, but here is a publicity photo from the show (circa 1949) and I think centered in the shot is the prop in question. I somewhat resembles early mics that used springs to suspend the "pickup" element in the center of an open "ring". But looking closely, one can see the components are merely drawn and/or painted.