The VU133 is a high voltage rectifier that was renamed the CV1133 when the CV register was introduced by the UK government in 1941.
See VU133 for another form of construction. The valve was designed to produce the EHT for the magnetron in a radar transmitter. The pulse power would be 0.5 to 1.0 MW but the average energy was quite low as the short pulses were produced at relatively long intervals.
The maximum working PIV is 6,500 Volts while the maximum of load PIV is 7,000 V. Peak anode current is 400 mA, reservoir capacitor is 1 μF max and the valve must have a minimum of 850 Ω series resistance.
The anode has a cylindrical central space and four equi-spaced side flanges for extar heat radiating area. The insulators are ceramic and the central cathode tube is of small diameter.
The top mica discs. The anode insulators are ceramic. The outer support rods are the cathode connection and the connecting wire from the cathode tube to the cross bar between the supports can be seen.
The lower mica discs. The anode insulators are again ceramic. The insulated heater is folded and passes four times through the cathode tube.
The classic envelope is 50 mm in diameter and, excluding the B4 base pins, is 124 mm tall.