The DH from M-OV is an indirectly heated triode for use as a detector or audio voltage amplifier and dates from 1931. The Osram label is stuck to the envelope.
The anode is made of mesh and is welded to the support rods. The grid is just visible inside the mesh anode.
The shaping of the mesh anode is revealed. The grid can be seen between the top of the anode and the top mica. Above the mica can be seen the twin insulated strands of the filament held by the rod. The etched markings are visible but the type designation is not visible.
In this enhanced image the faint etched marking of the DH can be seen. With the eye the identification of this valve is difficult.
The triangular top mica, and in this close-up the grid wire is clearer.
The balloon envelope is 50 mm in diameter, and excluding the B5 base pins is 108 mm tall.
Reference: 1043. Type DH was first introduced in 1931.