The CV404 is a high voltage half wave rectifier based on the VX9038 prototype. A rugged or 'reliable' version was made and given the designation CV4071.
The construction uses ceramic insulators because of the voltages involved. The peak forward current is 300 mA and the rectifier is also specified for pulse service, where the peak pulse current is 3 Amps. The series resistance must be at least 7,500 Ohms to protect the cathode. The maximum reservoir capacitor specified is 0.25μF.
The central oxide coated cathode has a significant space between it and the anode cylinder. The cooling required for the anode is provided by the fins. Close inspection shows that the U shaped channels that form the anode are formed from thin sheet and blackened to act as more efficient radiators.
The top of the anode, top ceramic insulator and connection from the anode to the top cap.
The wide glass tube envelope is 28 mm in diameter, and excluding the IO base pins is 98 mm tall.