The 6F30 exhibit is a purpose designed high gain VHF pentode. The mutual conductance is 15.6.
The valve was designed for use as a television IF amplifier. We have no details as to its noise performance.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins, is 52 mm long.
References: Datasheet, 3002 & 1040. Type 6F30 was first introduced in 1960.