[Elecraft] [K3] S-meter linearity

[Al Lorona]

I ran through an RF Gain calibration with the K3 Utility-- as I seem to do every three or four years for no good reason-- and then I checked the linearity of the S-meter. I've calibrated my S-meter for 1 S-unit = 5 dB because that way each tic mark represents 5 dB both above and below S9, making it easy to interpret. I use an Agilent E4433B signal generator.


I can go from +60 dB over S9 (-13 dBm) down to S2 (-108 dBm) by stepping the amplitude of the generator in exactly 5 dB steps and over this entire 95 dB range the segments of the S-meter track perfectly.


(The last S-unit, from S2 to S1, takes about an 8 dB delta to register on the S-meter.)


I gotta say, that's pretty remarkable. Not too many years ago S-meters were approximate guesses, but they've improved quite a bit, probably because of digital IFs and lookup tables. Very nice.

Al  W6LX