6AN8

The 6AN8 contains a medium-mu triode and a sharp-cutoff pentode in a nine-pin miniature envelope. Tung-Sol and Sylvania sheets describe it chiefly for television: the pentode can amplify the intermediate frequency or video signal and serve as a reactance tube; the triode suits low-frequency oscillators, sync separators or clippers, and phase splitters. The sections have separate cathodes, as the RCA pinout shows, allowing a designer to give them different bias conditions within one envelope.

The 6AN8 heater requires 6.3 V and 450 mA. In RCA's class A characteristics, the triode section has a 150 V plate supply, 15 mA current, an amplification factor of 21, about 4.7 kΩ plate resistance and 4,500 µS transconductance. For the pentode, the same sheet gives 125 V plate and screen-grid supplies, −3 V on the control grid, 12 mA plate current, 3.8 mA screen current and 7,800 µS transconductance. These are separate characteristic points for the two sections, neither maximum limits nor a universal circuit for every television set.

The sheets also differ in the rating system they use. RCA gives design-maximum values of 330 V on the plate of either section and 330 V for the pentode's screen-grid supply; a Sylvania sheet uses design-center ratings and gives 300 V for the plates instead. The screen supply voltage does not automatically equal the voltage actually present on the electrode, for which the documentation refers to specific conditions. Sylvania groups the 6AN8 with the 6AN8A and 5AN8 in its tables, but heater and other limits must be checked for the tube actually installed: appearing together in a document does not itself establish interchangeability.