The 3DT6 pentode was designed for use as a TV sound FM demodulator and a circuit is given in the attached data-sheet. The suppressor grid is close wound so as to be used as a second control grid.
See also17BF11 Compactron that has one pentode that is electrically similar to the 6DT6 the 6.3 Volt version of this valve.
The Tung-Sol name and Made in USA.
The anode has small notches through which the close wound g3 can be seen.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 47 mm tall.
Reference: Data-sheet. Type 3DT6 was first introduced in 1957. See also1957 adverts.
