The VT-80 is the American Government Type code for the Type 80 standard directly heated HT rectifier. The VT-80 or plain Type 80 was a very successful design and probably the first to use oxide coated ribbon filaments. The later 80S replaced the ribbon filament with an indirectly heated coated cathode.
The maximum reservoir capacitor is 32 µF and the minimum series resistance, to limit current, is 30 Ohms.
On the glass is the Type designation 80 thus showing direct equivalence.
The National Union maker's name.
The folded anodes with the flat section providing the space to stitch the sheet together, clamp to the support and provide cooling. The coated ribbon filaments form an inverted V in each of the rectifier sections.
The classic envelope is 44 mm in diameter and, excluding the UX4 base pins, is 102 mm tall.
References: Data-sheet, 1040 & 1043. Type VT-80 was first introduced in 1936. See also1936 adverts.