The VT-198A US Government procurement code and the commercial 6G6G both appear on this valve. It is an audio output pentode designed for radio receiver use where only a small output power is required. Thus the design emphasis was on minimising the overall power consumption both in HT and heater power.
The RCA logo.
The construction is as a pentode with three wire grids.
The classic envelope is 38 mm in diameter and, excluding the IO base pins the valve is 84 mm tall.