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I believe I basically understand that checking the box to select the "IARU Region 1 S-Meter Std" basically says S9 is a 50 microvolt signal into 50 ohms. I may be missing some details. The question is, if the box is not checked how is the calibration then defined? What's the distinction between the two options?


Ray Mikula
WA9ZVF

From https://en.wikipedia.org/wiki/S_meter#I ... dation_R.1

"IARU Region 1 Technical Recommendation R.1 defines S9 for the HF bands to be a receiver input power of -73 dBm. This is a level of 50 microvolts at the receiver's antenna input assuming the input impedance of the receiver is 50 ohms.

For VHF bands the recommendation defines S9 to be a receiver input power of -93 dBm. This is the equivalent of 5 microvolts in 50 ohms."

Hello Ray,
As Roger pointed out, IARU region one specification changes the definition of s9 from -73 dBm to -93 dBm for VHF frequencies and greater. if you un-check this box, s9 will remain at -73 dBm for all frequencies.

Sincerely

Tech_Support