The Hivac XD1.5V is a miniature battery triode on the peanut base. Thrower gives the base as Sm4 and so does Radiomuseum. Clearly both base versions existed.
The Peanut valve base in the UK was mainly associated with the Wecovalve in the early 1920s.
The anode is two bright trays either side of the grid. The helical filament tension spring can be seen above the top mica. The construction
The Hivac name.
The H on one of the anode plates was a way to make the thin nickel sheet more dimensionally stable - and good marketing.
Here the grid winding can be seen as can the thin filament wire.
The thin glass tube envelope is 15 mm in diameter and, excluding the Peanut base pins, is 55 mm tall.
