The AC/TP triode pentode frequency changer is of pinch construction but all internal structures are obscured by the external metalisation. The oscillator triode was designed to produce the 3 volts peak to peak injection required by the pentode section.
The balloon envelope is 43 mm in diameter and, excluding the B9 base pins, is 106 mm tall.
References: Datasheet, 1040 & 1043. Type AC/TP was first introduced in 1934.