S-Units Table NA5N

• An S-METER is calibrated by connecting a signal generator to the 50 ohm antenna terminal and setting the output power to 50uV, or -73dBm, and adjusting the S-meter calibration pot for a reading of S-9. 

• Many commercial receivers indicate non-standard readings. The calibration point may be correct, but the power level change between s-units are not in 6 dB steps.

• Notice that as the power level increases by 6dB, the voltage level doubles for each S-Unit from S1 through S9+6dB. 

  • One S-unit corresponds to a difference of 6 decibels (dB), equivalent to a voltage ratio of two, or power ratio of four

S-Units Table by NA5N

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S-Unit calibration measurements of several radios

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