The CV1401 specification is equivalent to the Mullard CL33. It is a high sensitivity output pentode for use in DC/AC mains operated equipment. The CL4 is electrically identical but is fitted onto a Ct8 base.
This audio power pentode works into an anode load of 4,300 Ohms and was designed to have its heater fed as part of a chain from the mains. Such valves were used in universal radio receivers and television sets. The anode voltage of 200 Volts is a clear indication of a design for use on European mains voltages.
The other side of the envelope is the standard Mullard CL33 identification thus showing that the valve just had the CV designation overprinted at some point.
The cathode is oval and the wire grids curve round it. The anode is cylindrical.
The classic envelope is 44 mm in diameter and, excluding the IO base pins, is 107 mm tall.
