[. . . ] Introduction The Mercury Model 1000 introduces a new concept in Dynamic Mutual Conductance tube testing. [. . . ] During normal test procedure no damage to tubes or to the tester can occur. There is automatic compensation built in, thus avoiding need for a line-adjust control, and the entire instrument is isolated for safety and long life. THE PANEL AND CONTROLS There are thirteen 3-position levers which are normally left in the lower position, marked "K". The beater circuits are independent, thus removing the need for an "open" position usually found in lever switch circuits. Levers 11 through 13 control the Grid, Heater Return and Plate circuits, respectively. Need for a separate bias control is elimated since this is automatically accomplished by the seting of the Grid circuit lever. The Plate circuit lever automatically selects the proper plate and screen voltage, enabling the Model 1000 to test all tubes including gas tubes, battery types, high voltage types, etc. [. . . ] The POWER jewwl shows when the instrument is turned on, and the Shorts jewel is used to detect inter-element shorts up to 1 megohm. [. . . ]