🔍 Key Concepts

• Class B amplifier tube operation and where the tube conducts on the input signal cycle • Relationship between amplification factor (μ), plate voltage, and grid bias to set the operating point • How mutual conductance (gm) affects the grid‑voltage/plate‑current relationship

💭 Think About

• For a Class B amplifier, think about how much of the input signal cycle the tube should conduct and what that implies for the grid being at or near cutoff with no signal. • Ask yourself: how does the amplification factor (μ = 25) relate the change in plate voltage to the required change in grid voltage to reach near‑cutoff from 1000 V plate supply? • Consider whether the required negative grid bias is typically a small fraction, large fraction, or roughly μ‑scaled fraction of the plate supply for Class B operation.

✅ Before You Answer

• Confirm how Class B bias differs from Class A (where is the quiescent operating point on the characteristic curve?). • Check that your chosen bias voltage would place the tube close to cutoff at no-signal conditions given μ = 25 and plate voltage = 1000 V. • Verify that the chosen answer is reasonable compared with typical grid‑bias magnitudes for large‑signal Class B operation (not unrealistically small or almost as large as plate voltage).