@tubetime Why does that CRT have an electrode in the centre? I've never seen one like that.
@philpem radial deflection. used for J-scope radar
@tubetime @philpem Types like the soviet 8LO30I
You run the XY plates to display a circle, and the inner pin (versus an ring that is not visible) for radial deflection, like pointers on a clock
Gregory's Server
@philpem radial deflection. used for J-scope radar