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

Why should you normally avoid transmitting on 14.100, 18.110, 21.150, 24.930 and 28.200 MHz?

Propagation beacons operate there.

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  1. Those frequencies are set aside for emergencies
  2. Those frequencies carry FCC bulletins
  3. A system of propagation beacon stations operates there ✔

Why: These are the homes of a worldwide network of propagation beacons. Hams listen to them to see which bands are open, so keeping the frequencies clear helps everyone.

Huh, didn't know that: FCC rules let beacons run under automatic control in the 28.20 to 28.30 MHz segment.

The dad joke
Why are beacons such patient teachers? They repeat the lesson until somebody hears it.
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References

Answer: A system of propagation beacon stations operates there. These are the homes of a worldwide network of propagation beacons. Hams listen to them to see which bands are open, so keeping the frequencies clear helps everyone.

  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
    A system of propagation beacon stations operates on those frequencies
    Checked 2026-10-10.
  2. 47 CFR 97.203 (Cornell LII mirror of eCFR) www.law.cornell.edu/cfr/text/47/97.203
    A beacon may be automatically controlled while it is transmitting on the 28.20-28.30 MHz
    Checked 2026-10-10.

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That's stuff everyone should know.