The VT-69 is the American purchase specification for the commercial 6D6. The valve is a variable μ pentode for AGC controlled amplifiers at RF and IF in superhet radio receivers.
Electrically the 6D6 (UX6 base) is identical to the Type 58 (UX6 base) and the 6U7G.
The Tung-Sol name on the base cap.
The screening continues at the top with a slot for the electrodes to emerge. The cathode tube is round and the control grid is wound on copper supports. The copper wire connecting the grid to the top cap is clearly seen. The other grid supports are rods indicating a true pentode.
The classic envelope is 38 mm in diameter, and excluding the UX6 base pins is 106 mm tall.
References: Data-sheet, 1040 & 1043. Type VT-69 was first introduced in 1936. See also1936 adverts.