SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/hamg-g8b11

What combination of a mixer's local oscillator and RF input frequencies is found in the output?

The sum and difference.

Start playing free

  1. The sum and difference ✔
  2. The ratio
  3. The average

Why: A mixer combines two signals and its output contains their sum and their difference. Mixing two RF signals is also called heterodyning.

Huh, didn't know that: The mixer input that is tuned to convert different signals to an intermediate frequency is the local oscillator.

The dad joke
A ham walks into a bar with a parrot on his shoulder. The bartender asks where he got it. 'Dayton, of course,' answers the parrot.
Like this card?
Play the game

References

Answer: The sum and difference. A mixer combines two signals and its output contains their sum and their difference. Mixing two RF signals is also called heterodyning.

  1. NCVEC 2023-2027 General Class Pool and Syllabus (6th Errata, Feb 4 2026) ncvec.org/downloads/General%20Class%20Pool%20and%20Syllabus%202023-2027%20Public%20Release%20with%206th%20Errata%20Feb%204%202026.pdf
    The sum and difference
    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 RadioWhat does the notch filter on many HF transceivers do?Ham RadioHow much signal strength change does one S unit typically represent?Ham RadioOn which HF bands do General licensees have some off-limits portions?

That's stuff everyone should know.