This exhibit was purchased as an OR2, a valve that was not listed in the literature. The lettering in yellow is badly worn. The third character is clearly a figure 2. The second letter is an A or an R and the first character could be a D or Q or O. HL2 is visually the closest match we have.
Another valve of almost identical construction was found on Ebay and it too had lost its identification.
The yellow lettering was in paint and not etched into the glass as with HL2.
The top mica: control grid supports are extended and provide support for the filament tension spring. The filament is an oxide coated single inverted V.
The balloon envelope is 42 mm in diameter, and excluding the B4 base pins is 83 mm tall.
References: Data-sheet, 1040 & 1043 Type HL2 was first introduced in 1931. See also1931 adverts.
