The Mullard EF50 was the ubiquitous red valve of WWII and as so many were needed by Governments several manufacturers made the Type. The RAF specification was called the VR91 for Valve Receiving 91.The circle with a Star looked familiar even though the writing was illegible, looking through the museum the logo was found to be that of Tungsram. The EF50 exhibit has a clearer example of the image.
The reverse of the can carries the EF50 Type designation that can be read and the maker's identification that we have not been able to read.The wide glass tube envelope is 34 mm in diameter and, excluding the B9G base pins, is 60 mm tall.References: Data-sheet & 1040. Type VR91 was first introduced in 1938. See also 1938 adverts. |
