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 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 also1961 adverts.
