This VR53 was made in Canada to the UK specification and the envelope also carries the old RAF stores code of 10E/11399. The VR53 Type designation dates this valve to before 1941 when it was renamed the CV1053 when the Common Valve register was introduced for all UK government departments to purchase to a standard specification.
The valve is a screened variable μ pentode designed for radio receiver use. The frequency range of operation would be up to 30 MHz and it was probably used as an IF amplifier. Type EF39 is essentially the same valve.
There is green paint under the black metal screening paint. The connecting wire can be seen on the left at the top of the base cap.
The additional symbols. The up arrow is for the RAF.
The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 82 mm tall.
References: Data-sheet & 1040. Type VR53 was first introduced in 1940. See also1940 adverts.
