This exhibit is an American made glass 6H6 double diode. The construction uses a small pinch and whilst being a small valve is much larger than the earlier all metal, and original, metal 6H6.
The diodes are low voltage low current signal rectifiers and not suitable for power supply service. The low current is reflected in the low heater power.
The longer leads associated with pinch construction adds extra lead inductance compared with the original metal version with the pressed glass foot.
The lower mica with the small diode sections above. The dome is opaque due to the gettering.
The wide glass tube envelope is 29 mm in diameter and excluding the IO base pins the valve is 56 mm long.
References: Data-sheet & 1040. Type VT-90A was first introduced in 1940. See also1940 adverts.
