The 5670 is a rugged special quality double triode developed from the 2C51. Applications include: mixers, oscillators and amplifiers operating to VHF. Also for use in multivibrators, synchronising amplifiers and industrial control. For airborne use it was certified up to 80,000 feet. It additionally had low microphany.
The orange paint of the RCA name. also the central screen sheet is clearly seen.
The two sections are spaced apart in the envelope. Through the hole in the anode wall can be seen the grid winding.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 35 mm tall.
Reference: Datasheet. Type 5670 was first introduced in 1952.