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The 572B is a replacement valve for the 811 transmitting tube. The valve is a hi μ power triode, used in many RF linear amplifiers. Examples are the KW1000 and Yaesu FL2100.

Typical operating conditions in amateur service are a Va of 2,400 V and an output power from a pair of 400 W. These devices are we believe still available from Svetlana.

The type number is presented as UEW 572-B. The 'UEW' seems to relate to United Electronics Waters. We assume that Waters was a component company of United Electronics.

Visually it conforms to the pattern of a medium power high voltage transmitting triode. The anode is connected to the top cap, the insulation is ceramic and the grid supporting rods are visible.

The 572B has a bonded thoria filament. This is a type of filament, typically made of tungsten, coated with thorium oxide (thoria) and bonded to a substrate like iridium. This design offers advantages in thermionic emission and durability compared to a thoriated tungsten filament alone. In high-power applications, thoriated tungsten filaments can fail catastrophically, while bonded thoria filaments are more resistant to such failure.

The base carries the maker's name Waters Manufacturing Inc of Wayland Mass. The other side carries the United Electronics name.

The carbon anode, ceramic insulator, filament tension springs and control grid.

The close wound control grid.

The pinch and lower components including the open ended cylinder - function unknown but possible has a gettering function.

The lower components.

The wide glass tube envelope is 50 mm in diameter and, excluding the UX4 base pins, is 154 mm tall.

Reference: Data-sheet. Type 572B was first introduced in 1961. See also 1961 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.