SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ham-3db-double-power

Going from 5 watts to 10 watts is closest to how many decibels?

3 dB, the decibel value for doubling power.

  1. 3 dB ✔
  2. 2 dB
  3. 10 dB

Why: Every doubling of power is about 3 dB, and every halving is about minus 3 dB. Going from 5 to 10 watts doubles the power.

Huh, didn't know that: Two halvings in a row, like 12 watts down to 3 watts, is about minus 6 dB.

The dad joke
Why did the decibel break up with the watt? It said the relationship was too logarithmic.
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Sources

  1. NCVEC 2026-2030 Technician Question Pool (Feb 19, 2026 release) https://www.ncvec.org/downloads/2026-2030%20Technician%20Pool%20and%20Syllabus%20Public%20Release%20Feb%2019%202026.pdf

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