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The CV5256 is a dedicated television EHT rectifier for picture tube supplies the commercial version is the U25. The valve is rated at 19 kV peak inverse volts, and this suggests an output voltage suitable for a 12 inch tube of say 16 kV.

The valve is also rated for sine wave use, and in this case an input voltage of 9,500 volts would be the maximum. The reservoir capacitor would need a value of 0.001 µF or less. In practice the capacitor would be formed between the internal and external graphite coatings on the picture tube itself.

The valve construction follows conventional practice in that the anode is bell shaped and there is a considerable separation between the cathode and the anode. The valve has flying leads so that it can be fitted directly across the line output transformer, where it would also derive its filament supply.

The two supports entering the anode. The lower holds the base of the insulated heater and the other connects to the cathode as well as the top of the heater.

The thin glass tube envelope is 18 mm in diameter and excluding the base wires is 58 mm tall.

References: Data-sheet & ¹⁰⁴⁰.

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.