• The Vintage B&K Dyna-Quik Model 550 Tube Tester is a classic American-made tester used for measuring the performance of vacuum tubes in various electronics equipment. Known for its reliability and durability, this specific model was manufactured by B&K, a reputable brand in the industry. With its distinctive design and functionality, this tube tester is a valuable tool for ensuring the proper functioning of electronic devices that rely on vacuum tubes for operation.