From TekWiki
Jump to navigation Jump to search
parallel 12B4s (center left) as pass elements in 585 power supply

The 12B4 is a power triode tube with a B9A (Noval) miniature 9-pin base. It has 5.5 W maximum plate dissipation, 1000 V peak plate voltage, and and 105 mA peak cathode current.

The 12B4 is used in the 126, 551, and 555, and as a pass tube in the power supply of the 513, 581 and 585.