Deep Dive: E6B04
The correct answer is A: Varactor diode. What type of semiconductor device is designed for use as a voltage-controlled capacitor is a varactor diode. Varactor diodes change capacitance with voltage. For amateur radio operators, this is important for component knowledge. Understanding this helps when using voltage-controlled capacitors.
Why Other Answers Are Wrong
Option B (Tunnel diode): Incorrect. Tunnel diode isn't a voltage-controlled capacitor - varactor diode is. Tunnel diode isn't the device. Option C (Silicon-controlled rectifier): Incorrect. SCR isn't a voltage-controlled capacitor - varactor diode is. SCR isn't the device. Option D (Zener diode): Incorrect. Zener diode isn't a voltage-controlled capacitor - varactor diode is. Zener diode isn't the device.
Exam Tip
Voltage-controlled capacitor = varactor diode. Think 'V'aractor = 'V'ariable 'C'apacitor (voltage-controlled). Varactor diodes change capacitance with voltage. Not tunnel diode, not SCR, not Zener - just varactor diode.
Memory Aid
Voltage-controlled capacitor = varactor diode. Think 'V'aractor = 'V'ariable capacitance. Varactor diodes change capacitance with voltage. Important for component knowledge.
Real-World Example
A voltage-controlled capacitor: It's a varactor diode. Varactor diodes change their capacitance based on the applied reverse voltage, making them useful for tuning circuits. This is the device - varactor diode.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E6B
Reference: 2024-2028 Question Pool · E6 - Circuit Components
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E6B topic.