The 6B8G double diode plus voltage amplifier pentode was designed for detector and first audio stages in radio receivers. The diodes would be for signal and AGC detection and the high impedance audio pentode would provide good small signal gain for feeding into an output pentode or beam tetrode such as the 6V6G.
The valve was made in America as the Amerty on the envelope indicates.
The Mullard name and Amerty brand.
The screened pentode is at the top with the shielded diodes below.
The classic envelope is 38 mm in diameter and, excluding the IO base pins, is 100 mm tall.
References: Data-sheet & 1040. Type 6B8G was first introduced in 1937. See also1937 adverts.
