1. A tetrode's plate and screen grid voltage is modulated via an audio transformer. 2. In an ECO, The screen grid acts as a plate for the triode oscillator. 3. Limits to screen grid dissipation, in addition to plate dissipation, are listed for power devices. 4. The screen grid may also generate considerable heat. 5. The negative resistance of the screen grid cancels the positive resistance of the tuned circuit, causing oscillations. 6. However, because the screen grid is not designed to handle high power, the oscillator's output power is limited. 7. When a tetrode or pentode is used, the screen grid voltage is usually about one-half the plate voltage. 8. An important part of the neutralization of a tetrode or pentode is the design of the screen grid circuit. 9. Some of the electrons pass through the screen grid to the plate, causing a current to flow in the load. 10. This means the screen grid has negative differential resistance with respect to the cathode, and can be used to create oscillations.
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