In an RF amplifier with fixed bias, as the...

Question 1 / 2707094OGQwxNT2EzBXuUxQAv

Question 1 of 2707094OGQwxNT2EzBXuUxQAv

In an RF amplifier with fixed bias, as the plate circuit is varied from below resonance to above resonance, what will the grid current do?

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Question 1 of 27070

In an RF amplifier with fixed bias, as the plate circuit is varied from below resonance to above resonance, what will the grid current do?

🔍 Key Concepts

• Resonance in tuned plate circuits and how current/voltage change at resonance • How grid current in a vacuum tube depends on RF drive level and grid voltage swing • Effect of changing plate circuit loading (off resonance vs at resonance vs above resonance) on grid excitation

💭 Think About

• When the plate circuit is exactly at resonance, what happens to the RF voltage gain of the amplifier compared to below or above resonance? • If the RF voltage at the plate increases or decreases, how does that affect the RF voltage on the grid (through coupling) and therefore the grid current? • Think about whether grid current is usually highest, lowest, or unchanged when the tube is most efficiently tuned (best resonance) in a fixed-bias RF stage.

✅ Before You Answer

• Confirm that in a tuned RF stage, resonance gives maximum RF voltage across the tuned circuit for a given drive • Remember that grid current flows mainly when the grid goes positive on RF peaks in a fixed-bias class C or B RF amplifier • Check whether more RF swing on the grid (due to better tuning) will cause more or less time with the grid positive, and thus more or less grid current, compared to off-resonance.

Question 1 of 27070

In an RF amplifier with fixed bias, as the plate circuit is varied from below resonance to above resonance, what will the grid current do?

The grid current will rise slightly at resonance

The grid current will dip slightly at resonance

The grid current will not vary

None of the above

Question 1 / 2707094OGQwxNT2EzBXuUxQAv

Question 1 of 2707094OGQwxNT2EzBXuUxQAv

In an RF amplifier with fixed bias, as the plate circuit is varied from below resonance to above resonance, what will the grid current do?

Back

Question 1 of 27070

In an RF amplifier with fixed bias, as the plate circuit is varied from below resonance to above resonance, what will the grid current do?