SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ham-hardline-lowest-loss

Which type of feed line has the lowest loss?

Air-insulated hardline.

  1. 50-ohm flexible coax
  2. Air-insulated hardline ✔
  3. 75-ohm flexible coax

Why: Hardline has a solid outer conductor and mostly air inside, so it loses far less power than flexible coax, especially at high frequencies.

Huh, didn't know that: Foam-dielectric coax also has less loss per foot than solid-dielectric coax.

The dad joke
Why is hardline so tough? It never bends the rules.
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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

Test yourself in the game

Ham RadioWhat happens to coaxial cable loss as signal frequency is increased?Ham RadioWhat happens to power lost in a feed line?Ham RadioWhich of the following causes failure of coaxial cables?

That's stuff everyone should know.