The picture at left shows a 6Y6GA rebranded as "8417" by International Components Corporation to the left of a real 8417. The second picture shows the same fake 8417 next to a correctly branded 6Y6GA. Note that the plate structure of the real 8417 almost touches the glass, while there is a lot of space between the plate and the glass on a 6Y6GA
This fake is scary, because a 6Y6GA tests "good" as a 8417 on most tube testers, including my Hickok 539C.
While both the 6Y6GA and 8417 are beam power output tubes, the similarity ends there. The 8417 has nearly 300 percent of the ratings of the 6Y6GA in every catagory. Three important parameters are:
Max Plate Watts: 8417 = 35W; 6Y6GA = 12.5W
Max Plate Volts: 8417 = 660V; 6Y6GA = 200V
Max Screen Volts/Watts: 8417 = 500V/5.0W; 6Y6GA = 200V/1.75W