The 6GH8A is a triode pentode with separate cathodes designed for television receiver use. The valve is specified for multivibrator-type line deflection oscillators and/or AGC amplifier and sync-separator functions.
The RCA logo and within the triode on the right.
The triode with stitched anode and copper grid supports.
The pentode section has the grid axis at right angles to the triode.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 48 mm tall.
Reference: Data-sheet. Type 6GH8A was first introduced in 1961.