E7H08: NP0 capacitors: Of the following components can be used

Q: Which of the following components can be used to reduce thermal drift in crystal oscillators?

The correct answer is A: NP0 capacitors. The correct answer is A: NP0 capacitors. NP0 capacitors (also called C0G capacitors) can be used to reduce thermal drift in crystal oscillators. NP0 capacitors have a very low temperature coefficient (essentially zero temperature coefficient), making them stable over temperature changes. Crystal oscillators use capacitors in their circuits (for loading, coupling, or tuning). If these capacitors change value with temperature, the oscillator frequency will drift. NP0 (Negative-Positive-Zero) capacitors have a temperature coefficient near zero, so their capacitance doesn't change significantly with temperature. This helps maintain stable oscillator frequency over temperature variations. NP0 capacitors are more expensive than standard capacitors but are essential for temperature-stable oscillators.

Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E7H

E7H08E7H

Which of the following components can be used to reduce thermal drift in crystal oscillators?

Previous Next

Deep Dive: E7H08

The correct answer is A: NP0 capacitors. NP0 capacitors (also called C0G capacitors) can be used to reduce thermal drift in crystal oscillators. NP0 capacitors have a very low temperature coefficient (essentially zero temperature coefficient), making them stable over temperature changes. Crystal oscillators use capacitors in their circuits (for loading, coupling, or tuning). If these capacitors change value with temperature, the oscillator frequency will drift. NP0 (Negative-Positive-Zero) capacitors have a temperature coefficient near zero, so their capacitance doesn't change significantly with temperature. This helps maintain stable oscillator frequency over temperature variations. NP0 capacitors are more expensive than standard capacitors but are essential for temperature-stable oscillators.

Why Other Answers Are Wrong

Option B: Incorrect. Toroidal inductors are used for their magnetic properties and low radiation, but they don't specifically reduce thermal drift in crystal oscillators. Option C: Incorrect. Wirewound resistors are stable resistors, but they don't reduce thermal drift in crystal oscillators. The drift comes from capacitors, not resistors. Option D: Incorrect. Non-inductive resistors are used to avoid inductance, but they don't reduce thermal drift in crystal oscillators.

Exam Tip

Reduce thermal drift = NP0 capacitors. Remember: NP0 (C0G) capacitors have near-zero temperature coefficient and are used to reduce thermal drift in crystal oscillators.

Memory Aid

**R**educe **T**hermal **D**rift = **N**P0 **C**apacitors (think 'RTD = NPC' = NP0 Capacitors)

Real-World Example

You're building a crystal oscillator that needs to stay stable over a wide temperature range. You use NP0 capacitors in the oscillator circuit instead of standard ceramic capacitors. The NP0 capacitors don't change value with temperature, so your oscillator frequency remains stable as the temperature changes, preventing thermal drift.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E7H

Reference: FCC Part 97.3

Key Concepts

NP0 capacitors Thermal drift Crystal oscillators Temperature stability

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E7H topic.