The 6AS6 is a physically small amplifier pentode. It is designed for dual control and therefore the suppressor has a short grid base or control range.
The end wall of the anode has notches so the suppressor grid support can be seen. As this is a dual control valve the suppressor grid has a much smaller pitch than a single control pentode.
The Russian Type designation is 6Ж1П.
The pentagon logo.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 38 mm tall.
References: Data-sheet & 1040. Type 6AS6 was first introduced in 1949. See also1949 adverts.