The 13201A voltage stabiliser from Mullard has a voltage regulation of only two Volts from the minimum current of 15 mA to the maximum of 200 mA. Thus it was designed to supply the controlled circuit directly as not as a voltage reference for a regulated power supply.The striking voltage given by Thrower is 135 Volts.
The large anode closed cylinder and central rod cathode. The heavy anode is supported by a collar clamped around the pinch stem.
The open end of the anode has a ceramic plug. The central cathode is augmented by a striker electrode placed near the anode to initiate the discharge.
The wide glass tube envelope is 47 mm in diameter and, excluding the B4 base pins, is 145 mm tall.