The 6AV6 was designed for signal detection, AGC detection (rectification) and first audio voltage amplifier in superhet radio sets. The valve came in three heater versions The 3AV6 at 3.15 V, the 4AV6 at 4.2 V, the 6AV6 at 6.3 V and the 12AV6 at 12.6 V. Like the similar 6AT6 this design specification was interpreted by several manufacturers.
The construction has a central triode with the two diodes formed above the top mica by the bright shaped anodes.
The triode is slightly larger than in the 6AT6 and the active cathode area for the diodes is almost twice that in the 6AT6. The getter support seen on the left is connected to the cathode.
The etched 6AV6 can be seen at the top of the image. The printed Marconi inscription suggests that the Canadian factory that made this valve added the brand as required to the common 6AV6 valve.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 47 mm tall.
References: Data-sheet & 1040. Type 6AV6 was first introduced in 1948.