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SESK: Stuff Everyone Should Know · sesk.info/hamg-rtty-shift

What is the most common frequency shift for RTTY on the amateur HF bands?

170 Hz.

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  1. 170 Hz ✔
  2. 85 Hz
  3. 850 Hz

Why: RTTY sends two tones, called mark and space, a fixed distance apart. On amateur HF the usual spacing is 170 Hz.

Huh, didn't know that: If an RTTY signal won't decode, the mark and space tones may be reversed, the baud rate wrong, or the sideband wrong.

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References

Answer: 170 Hz. RTTY sends two tones, called mark and space, a fixed distance apart. On amateur HF the usual spacing is 170 Hz.

  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
    170 Hz
    Checked 2026-10-10.

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