🔍 Key Concepts

• Vacuum tube types: triode, tetrode, pentode and how many grids/electrodes each has • Neutralization in RF amplifiers: why it is needed to prevent oscillation or instability • How adding extra grids (screen, suppressor) affects inter-electrode capacitance and feedback in a tube

💭 Think About

• Which tube has the fewest elements and therefore the highest input-to-output capacitance, making neutralization more important? • How does the presence of a screen grid in a tetrode change the coupling between plate and control grid compared with the simpler tube? • Between triode, tetrode, and pentode, which one usually needs neutralization at lower frequencies, not just ultra high frequencies?

✅ Before You Answer

• Verify how many active electrodes each device has: cathode, anode (plate), and number of grids • Check which tube’s design leads to the greatest plate-to-grid capacitance, requiring neutralization over a wider frequency range • Confirm that in the correct comparison, the tetrode needs neutralization only at ultra high frequency, while the other choice needs it at lower RF frequencies as well