The CV1144 (commercially the BT19) is a hot cathode mercury vapour thyratron. The old Navy service code is NGT5.
The KB/EN identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the EN identifies the maker as Thorn-AEI, Sunderland.
The reverse carries the original Type designation of BT19 and the pre merger company of BTH Rugby. Clearly older stock overprinted for sale to the UK Government.
The filament connections pass into the space inside the outer cylinder which leaves the cylinder as the grid or trigger electrode.
The anode connected to the top cap.
The classic envelope is 54 mm in diameter, and excluding the B4 base pins is 132 mm tall.
