The 6A7E frequency changer is on a UX7 base, its sister valve the 6A8 is identical electrically but is on an International Octal base. We also have a 6A7 in the museum that is given as identical. The 6A7S appears to denote an external metalisation version.
The gettering is only on one side, thus allowing a clear view of the construction.
The screening grids are strapped together above the top mica. g4 can be seen connecting to the top cap.
The pinch and lower electrodes. The two rods (g2) are connected together below the mica and act as the oscillator anode.
The classic envelope is 38 mm in diameter and, excluding the UX7 base pins, is 100 mm tall.
References: Data-sheet, 3002 & 3002. Type 6A7E was first introduced in 1937.