The 6L7 design of a VHF pentagrid converter (mixer) is aimed at ensureing maximum isolation between oscillator and signal, and to provide a mixer which is efficient at VHF where stable oscillation would otherwise require a separate VHF oscillator triode.
For applications where a self-oscillating mixer (ie. pentagrid converter) could provide adequate performance there were other Octal types specifically designed for the purpose.
The anode does not cover all of the length of the grids and the wire construction can be seen. The number of wires makes identification difficult through the glass.
Another image of the top of the anode. The oxide coated cathode can be seen.
The lower end of the electrode assembly. Note the five heater strands and copper control grid support.
The classic envelope is 39 mm in diameter and, excluding the IO base pins, is 98 mm tall.
References: Datasheet, 1043 & 3002. Type 6L7G was first introduced in 1936.