866A

{{Infobox vacuum tube

|image = 866 mercury rectifier 1.jpeg

|caption = Westinghouse 866A mercury vapor half-wave rectifier tube.

|classification = Diode

|cathode_type = Directly heated

|heater_voltage = 2.5

|heater_current = 5 A

|max_current = 250 mA

|max_voltage = 5000

|reference = RCA Transmitting Tube Manual TT-3, 1940

}}

The 866 is a mercury vapor half-wave rectifier intended for high-voltage applications. The voltage drop is approximately 15 volts up to 150 Hz. To avoid unwanted shorts the tube must be operated in a vertical position and the filament preheated for at least 30 seconds before applying the plate voltage.{{cite web|url=http://www.uli.de/tubes/866a.htm|title=866|website=www.uli.de}}

Construction

Structurally, it consists of a linear electrode arrangement; a cup shaped anode with top cap and a cylindrical cathode. The socket is a medium 4 pin bayonet UX-4 and the glass envelope is ST-19. The 2.5 volt/ 5 Amp filament is connected to pins 1 and 4.

Operation

Under normal operating conditions the tube glows blue and mercury droplets are visible.

Pictures in working conditions

{{Gallery

|File:866_mercury_rectifier_glow_5mA.jpeg|Westinghouse 866A mercury vapor half-wave rectifier tube. Glowing with 5mA

|File:866_mercury_rectifier_glow_5mA_dark_environ.jpeg|Westinghouse 866A mercury vapor half-wave rectifier tube. Glowing with 5mA in the dark (long exposure)

|File:866 mercury rectifier glow 180mA dark environ.jpeg|Westinghouse 866A mercury vapor half-wave rectifier tube. Glowing with 180mA in the dark.

}}

References

External links

[https://www.r-type.org/exhib/aab0018.htm 866 @ The National Valve Museum]
[http://www.radiomuseum.org/tubes/tube_866a.html 866A at Radiomuseum.org]

Category:Vacuum tubes

Category:Electric power conversion