El-Tronics Inc. Beta Gama Survey Meter Model SGM-18A

This device was manufactured in the late 40's for the Atomic Energy Commission. A very historical instrument. Made to use two 45 volt "B" cells, one 1.5 volt radio "A" cell, and three 300 volt cells. I decided to try and make it work with a low voltage GM tube and make a corresponding power source. For what I came up with it works reasonably well.