The Supreme Model 504-A is a complete tube, battery and set tester for checking the static condition of radio receivers and parts as well as many other types of electronic apparatus. The tube testing circuit of the Model 504A is designed to classify receiving type tubes by the emission principle. This type of tester has long been recognized to be the most accurate of any simple test on vacuum tubes. By checking the cathode or filament, as the case may be, for its ability to emit electrons or current to the other elements of the tube, the quality of the tube may be accurately classified. In setting the limits on the tubes as shown on the roll chart, Supreme engineers worked closely with tube manufacturers. Recommended loads and voltages are used throughout the tester. The battery testing function provides a load upon the battery or cell under test which represents the average current drain on that particular type of battery. The discard points used in this section of the Model 504-A are those recommended by the manufacturers of portable radio batteries. The multimeter section of the Model 504-A incorporates seven choice functions built around a meter with a sensitivity of 500 microamperes. This section includes a total of twenty-nine Carefully selected ranges and also provisions for electrolytic and electrostatic capacitor checks. Twenty-seven multimeter functions are operated from only one pair of pin jacks by means of two sets of push button switches which make it a completely automatic unit.