The VR150/30 is a cold cathode voltage regulator it exhibits a near constant voltage drop for currents within the range 5 mA to 40 mA. The voltage is 150 plus or minus 5.5 Volts.
The RCA logo on the base cap. The octagonal border on the glass is typical RCA.
The Type designation and the large hole in the envelope.
The wide glass tube envelope is 38 mm in diameter and, excluding the IO base pins, is 86 mm tall.
References: Data-sheet, 1040 & 3002. Type VR150/30 was first introduced in 1939. See also1939 adverts.
