The U301 is an efficiency diode for television line scan. In use it returns energy from the circuit inductances back to the HT rail and hence to the reservoir capacitor.
The peak inverse voltage is 4,500 Volts, the peak anode current is 600 mA with a maximum rectified current of 120 mA. The heater needs very good insulation in these rectifiers and for the U301 the maximum heater - cathode voltage is 4500 Volts.
The U301 has a 200 mA heater and the U191 has the same ratings but has a 300 mA heater.
The remains of the Ediswan border can just be seen in the main image together with the Type designation U301.
The anode cross section takes the form of a T.
Face view of the anode with the central flange facing the camera.
The cathode can be seen connected to the top cap and within the cathode tube is a ceramic tube that the heater has been threaded through. This gives extra heater/cathode insulation. This is required as the heater will be part of the standard heater chain but the insulation has to withstand up to 900 Volts.
Another view showing how the folded anode has been stitched together.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 89 mm tall.
References: Data-sheet, 3002 & 1040. Type U301 was first introduced in 1953. See also1953 adverts.
