[R-390] Ballast Tube Thread

[JamesMiller]

History of Amperite company began with Ballast Tubes

1922---Amperite Business Incorporated in New York City, NY by Samuel
Ruttenberg-produced cartridge-type Automatic Adjusting Resistors( ballast
current-regulators) for tube-operated AC/DC radio sets

1930(circa)---Amperite Began making hermetically-sealed ballast regulators
in vacuum tube form with helium and hydrogen gas...



http://www.amperite.com/DesktopDefault.aspx?tabid=10