Class A2
Class A2 amplifiers can overcome a high Rp by driving the grid positive with respect to the cathode. Because this makes the grid a secondary anode, it too will draw current from the cathode while accelerating the remaining electrons towards the plate. Grid currents can place extreme demands on the driving circuitry, sometimes requiring as much as 8 watts input for larger tubes such as the 211.
Read more about this topic: Single-ended Triode
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