The 6BJ6 is a variable μ RF pentode designed for broadcast radio receiver applications. A key feature is the modest heater power making it attractive for mobile applications.
The Bentley Acoustic Corporation was a UK reseller that advertised in hobby magazines.
The anode covers almost all of the inner structure.
|Looking into the gap at the base of the anode, the screen grid can be seen. It passes flat across the control grid and cathode. The control grid and suppressor grids are not visible in this image.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 46 mm tall.
References: Data-sheet, 1040 & 3002. Type 6BJ6 was first introduced in 1947. See also1947 adverts.