The 6A7 is an American Pentagrid converter or heptode mixer. The 6A8 is the same valve electrically but on an IO base. We also have the 6A7E in the museum.
The Champion makers name on the base cap.
The top mica: grid four connects to the top cap and is the point where the input signal is entered. Grid one is the oscillator control grid and grid two is a pair of vertical rods that act as the oscillator anode. Note that the two screen grids, g3 and g5, are bridged as can be seen on the left.
The classic envelope is 38 mm in diameter and, excluding the UX7 base pins, is 101 mm tall.
References: Datasheet, 1040 & 1043. Type 6A7 was first introduced in 1933.