The QS108/45 is a voltage stabiliser with a separate priming anode. The tube strikes at 120 Volts and regulates to 108 Volts for currents of 5 to 45 mA. Over this current range the voltage will vary by 5 Volts, the 108 Volts occurs at a current of 25 mA.
The cathode cylinder with mica discs top and bottom. The anode is a central rod.
The valve is also marked as a CV422. The locating pip is needed as the pins are all equally spaced around the pin circle. The depression at the base of the spigot allows a spring to lock the valve in place in the valve holder.
The cathode seam shows how thin the metal sheet is.
The wide glass tube envelope is 28 mm in diameter, and excluding the B8B base pins is 64 mm tall.
References: Data-sheet. Type QS108/45 was first introduced in 1954. See also1954 adverts.
