The NU7 is an interesting rectifier as the mercury can be clearly seen on the inside of the envelope. The heater is a thick coil of ribbon and the anode is a curved plate.

The civilian prototype of the NU7 is the MOV Type GU1, introduced in the mid 1930s. The GU1 was very popular as a rectifier for cinema amplifiers (etc) but it had a short life and was discontinued in favour of the GU50. The Navy, as ever, wanted a continuing supply of spare valves long after everyone else had converted to the superior type.

Our exhibit was probably supplied by Ediswan Mazda, probably in the late 1940s.

See also GU1 for operating details.

The balloon envelope is 42 mm in diameter and excluding, the B4 base pins, is 94 mm tall.

This exhibit was last updated on 07 August 2006