SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/hame-class-d-amplifier

What is a Class D amplifier?

A switching amplifier built for high efficiency.

Start playing free

  1. An amplifier using switching for high efficiency ✔
  2. An amplifier biased to be free from distortion
  3. A low power differential amplifier

Why: Class D output devices are either fully on or fully off. They waste very little power as heat, so they run cool and efficient.

Huh, didn't know that: An RF switching amplifier needs an output filter to remove harmonic content (E7B03).

The dad joke
What does an engineer say when an amplifier works but has some harmonic distortion? Fundamentally, it's not really a problem.
Like this card?
Play the game

References

Answer: An amplifier using switching for high efficiency. Class D output devices are either fully on or fully off. They waste very little power as heat, so they run cool and efficient.

  1. NCVEC 2024-2028 Amateur Extra Question Pool, E7B02 (4th errata, Feb. 4, 2026) www.ncvec.org/downloads/2024-2028%20Extra%20Class%20Question%20Pool%20and%20Syllabus%20Public%20Release%20with%204th%20Errata%20Feb%204%202026.pdf
    A. An amplifier that uses switching technology to achieve high efficiency
    Checked 2026-10-11.
  2. NCVEC 2024-2028 Amateur Extra Question Pool, E7B03 (4th errata, Feb. 4, 2026) www.ncvec.org/downloads/2024-2028%20Extra%20Class%20Question%20Pool%20and%20Syllabus%20Public%20Release%20with%204th%20Errata%20Feb%204%202026.pdf
    A. A filter to remove harmonic content
    Checked 2026-10-11.

Think this answer is wrong? Tap "Challenge this answer" on the card in the game and tell us why.

Test yourself in the game

Ham RadioWhy are switching amplifiers more efficient than linear amplifiers?Ham RadioOutside parts of Alaska, what is the maximum radiated power allowed on the 630 m amateur band?Ham RadioHow tall may an antenna used on the 2200 m and 630 m bands be above ground?

That's stuff everyone should know.