The CV3797 is a caesium photocell with a common anode rod and twin semi-circular photo cathodes. The bottom cathode is k(1) and the top k(2). The commercial equivalent is the V944A and this is quoted in the specification.
The Type designation is clearer here.
The twin photo-cathodes.
The semi-circular shape of the cathodes and the rod anode in front.
The original box showing the maker as Gilbert Photo Electronics Ltd.
The wide glass tube envelope is 32 mm in diameter and, excluding the IO base pins, is 83 mm tall.
Reference: Data-sheet. Type CV3797 was first introduced in 1951. See also1951 adverts.
