The XH1.5V or XH1.5 miniature triode dates from 1935. The base is the Hivac small four pin, and the design use was for hearing aids but they were useful for miniature radios and radio controlled models.
Filament operation and anode supplies were both to be taken from dry calls.
The 1.5V etched into the glass. The top mica carries the filament tension spring. This is helical with the top fashioned into a vertical drop with a hook at the end.
The box anode in the centre with a support rod on the right and getter holder fixed to the left side of the top mica.
The anode plates have been spot welded to their support rods. The grid supports can be seen at the top with the notch spacing indicating the winding pitch.
Turned slightly for a clearer view of the layout.
The thin glass tube envelope is 14 mm in diameter and, excluding the base pins, is 53 mm tall.
References: Data & 1020. Type XH1.5 was first introduced in 1935. See also1935 adverts.
