The HA1 is a low capacity acorn triode designed to operate at UHF.
The pin connections are listed in the attached data-sheet.
The base is at the top of this image and the heater connections are the prominent feature. The anode is seen face on and the grid can be seen to be wound on copper supports. The notches show the grid winding pitch.
The gauze above the up arrow and the Z is the getter holder.
The faint getter deposit can be seen top left in this picture. The pins are sealed into a hard glass ring.
The thin glass tube envelope is 14 mm in diameter, and including the base pins is 32 mm tall.
Reference: Data-sheet. Type HA1 was first introduced in 1936. See also1936 adverts.
