B&K Dyna-Quik 650, Tube TesterCondition:* Used, Unable To Test. Sold As-Is. As Pictured. Additional Notes:* The Model 650 was a rather high-end portable tube tester that was capable of analyzing hundreds of tube types. * Many dials and switches are used to set up heater filament voltage, plate and grid voltages* There are two active components in the circuitry – an RCA 83 mercury vapor rectifier tube and a 6AV6 double-diode triode tube. B&K Dyna-Quik 650