Introduction The Mercury Model 1000 introduces a new concept in Dynamic Mutual Conductance tube testing. A combination of lever-switch versatility and multiple socket speed brings a true Mutual Conductance (Gm) tube tester into the popular price range for the first time. The Model 1000 tests for shorts between any tube elements. The 2Color GAS scale on the meter shows grid leakage and gas content with a sensitivity of over 150 megohms. Tubes such as rectifiers, power amplifiers, etc. are checked for Dynamic Cathode Emission (Em), with tube quality shown on the 3-color meter scale. The Model 1000 circuit is designed for maximum speed and accuracy in 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". Levers 1 through 10 represent corresponding tube elemets. 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 SELECTOR knob provides 12 heater voltage setting, which Cover all tubes in use today. The LOAD control adjusts meter sensitivity. The FUNCTION switch sets up the tests in proper sequence and also Serves as the POWER switch. 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.