Jackson 648A Tube Tester

Here is our rebuilt and calibrated Jackson 648A dynamic conductance tube tester,  All meter shunt and plate load resistors changed to 0.1% tolerance metal film Vishay 1 W.  1S5 tube eliminated for solid state and wiring adjusted to match a 648R or S model.  Secondary voltages. plate currents and heater voltages verified to make this a very reliable and accurate unit.  Awesome build quality with big iron inside.