The NU34 is a half wave low current EHT rectifier as specified by the Royal Navy.
This low current half wave rectifier was designed for provision of EHT in such applications as Radar and Oscilloscopes where Cathode Ray Tube indicators were used.
Mullard and M-OV produced this specification using the vertical cylindrical anode. Cossor used their original design of reliable saddle anode as can be seen in VU120.
The other side of the glass has the RAF designation of VU134 and the old stores code of 10E/100.
The unused base pins, pinch and lower end of the anode.
Here the coated cathode tube is plain at the lower end with a strap to the middle vertical support. The coiled heater in ceramic insulation can be seen. One side of the heater support is connected to the cathode support.
The top of the cathode tube is of reduced diameter and it and the two supports are held by a mica plate.
This box contains a NU34 and the paper label from 1943 gives the new Type designation of CV1134. This two part pasteboard carton cradles the glass in horse hair. The box is 74 mm square and 138 mm tall.
This box is 57 mm square and 158 mm tall. The same wording as the box above is seen on this box.
The end of the box and the date of 1955 is when it was last tested.
The classic envelope is 45 mm in diameter, and excluding the B4 base pins, is 109 mm tall.