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SESK: Stuff Everyone Should Know · sesk.info/ham-causes-of-rf-interference

Can fundamental overload, harmonics and spurious emissions all cause radio frequency interference?

Yes, all three can cause RF interference.

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  1. No, only harmonics can
  2. Yes, all three can ✔
  3. No, only spurious emissions can

Why: Overload swamps a nearby receiver, harmonics land on multiples of your frequency, and spurious emissions are stray signals. Any one of them can cause interference.

Huh, didn't know that: The second harmonic of a 146 MHz signal falls at 292 MHz, twice the frequency.

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Harmonics, overload and spurious emissions walk into a TV. The picture gets very confused.
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References

Answer: Yes, all three can. Overload swamps a nearby receiver, harmonics land on multiples of your frequency, and spurious emissions are stray signals. Any one of them can cause interference.

  1. NCVEC 2026-2030 Technician Question Pool (February 19, 2026 errata) ncvec.org/downloads/2026-2030%20Technician%20Pool%20and%20Syllabus%20Public%20Release%20Feb%2019%202026.pdf
    Which of the following can cause radio frequency interference? A. Fundamental overload B. Harmonics C. Spurious emissions D. All these choices are correct
    Checked 2026-10-09.

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Ham RadioWhich of these is prohibited for amateur radio operators?Ham RadioWhat must U.S. amateurs do in a secondary band segment?Ham RadioTwo stations on the same frequency interfere with each other. What should happen?

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