Deep Dive: E4D08
The correct answer is C: Nonlinear circuits or devices. What causes intermodulation in an electronic circuit is nonlinear circuits or devices. Nonlinearity creates IMD products. For amateur radio operators, this is important for understanding IMD. Understanding this helps when troubleshooting interference.
Why Other Answers Are Wrong
Option A (Negative feedback): Incorrect. Negative feedback reduces nonlinearity, doesn't cause IMD - nonlinear circuits cause IMD. Negative feedback isn't the cause. Option B (Lack of neutralization): Incorrect. Lack of neutralization causes oscillation, not IMD - nonlinear circuits cause IMD. Neutralization isn't the cause. Option D (Positive feedback): Incorrect. Positive feedback causes oscillation, not IMD - nonlinear circuits cause IMD. Positive feedback isn't the cause.
Exam Tip
Intermodulation cause = nonlinear circuits or devices. Think 'I'ntermodulation = 'I'nterference from 'N'onlinearity. Nonlinearity creates IMD products. Not negative feedback, not lack of neutralization, not positive feedback - just nonlinear circuits.
Memory Aid
Intermodulation cause = nonlinear circuits or devices. Think 'I'ntermodulation = 'N'onlinearity. Nonlinearity creates IMD products. Important for understanding IMD.
Real-World Example
Intermodulation in an electronic circuit: It's caused by nonlinear circuits or devices. When a circuit is nonlinear, it can mix signals and create intermodulation products. Linear circuits don't create IMD. This is the cause - nonlinear circuits or devices.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E4D
Reference: 2024-2028 Question Pool · E4 - Amateur Practices
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E4D topic.