This exhibit from Mazda is marked as 6F30/EF184 showing complete equivalence. The valve 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.
The EF184 Type designation. The actual pentode section is 12 mm high.
The layout of the internal structure. The anode is two small plates joined by a strap. The suppressor grid is an open pitch helix and the inner grids pass flat across the cathode.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins, is 53 mm long.
References: Data-sheet, 3002 & 1040. Type 6F30 was first introduced in 1960. See also1960 adverts.