Type G Pliotron with US Navy Type designation CG-890. The almost identical valve when supplied to the US Army was known as the VT-13.
The CG-890 was initially the CG-886 on a four pin bayonet base. Here the closed cylinder or inverted cup anode has been replaced by an open cylinder and this change improved the valve's performance.
From the Tyne Collection.
Thanks to Joe Gruber for sending the image.
The balloon envelope is mm in diameter and, excluding the UV base pins, is mm tall.
References: J Gruber, & 1047. Type CG-890 was first introduced in 1918.
Absolute Maximum Operating Conditions¶
Updated October 20, 2019. shape:balloon construction:pinch type:triode age:pre.1920 base:uv pins:4 pin: