🔍 Key Concepts

• Cathode bias in vacuum tube RF amplifiers • Purpose of a bypass capacitor across a resistor • Relationship between AC gain and keeping the RF signal off the bias resistor

💭 Think About

• When RF signal current flows through a cathode-bias resistor without a bypass capacitor, what happens to the voltage across that resistor during the signal cycle? • If you place a capacitor in parallel with the cathode resistor, how does this affect AC (RF) variations versus DC bias? • How does stabilizing the DC bias while providing a low-impedance path for RF affect the amplifier’s gain?

✅ Before You Answer

• Identify which statement describes stabilizing DC bias against RF variations • Identify which statement describes increasing stage gain by avoiding signal degeneration across the cathode resistor • Check whether the bypass capacitor can realistically do both functions at the same time in an RF amplifier circuit