em81-2.jpg (10004 bytes)  

Magic eye for side view.
The fluorescent target is U-shaped and the anode is connected to a centered rod giving one shadow with varying angle depending upon the control voltage. Mainly used as a tuning indicator.  
Equivalent 6DA5
Similar type  
With different Vf 19DA5, UM81
CV number CV5055
Swedish Mil.nr.