The Vintage B&K Dyna-Jet Dynascan 747 Mutual Conductance Tube Tester Checker #1 is a high-quality, reliable tool for testing the performance of vacuum tubes. Manufactured by B&K in the United States, this Dyna-Jet model offers accurate and efficient testing capabilities. With its mutual conductance technology, this tube tester provides valuable insights into the functionality of the tested tubes, ensuring optimal performance in various electronic devices. Perfect for professionals in the electronics industry, this vintage tester is a valuable addition to any testing and measurement toolkit. Item powers on but not sure if it works correctly no tubes to test with.