No standards. There is no international body in charge of the definition of an S-unit.
Just history. Somewhere I have a .jpg file from an ebay posting of a lovely pristine 30's receiver with an S meter that showed S units on top side of scale, and dB's on the bottom side. 6 db per unit. The very simple origin of that was that moving up an S unit was doubling the signal voltage. Given circuits back then, the bottom of the scale was the point at which AGC intercept occurred. The "about" portion of the S3 in the K3 doc comes from not having strictly calibrated RF gain until just a few beta firmware releases ago. After the calibration, my K3's S3 light kicks on at input of -109 dBm, and S4 kicks on at -103. 1 uv exceeds -109 but falls short of -103, thus only showing up to the S3 light. If one is thinking that S3 *IS* -109, then 106 or 105 or so is "about" S3. If one is thinking that S3 is a range, when the S3 lamp is on then it's S3 (exceeds -109 but not -103 dBm), then by definition S3 is fuzzy. Use of the word "about" is a lot more straightforward for doc than what I just said. Another example of when less is more. 73, Guy. On Tue, Nov 17, 2009 at 1:45 PM, Mike Scott <[email protected]> wrote: > Geoff said>For practical purposes S3 is probably close enough rather than > "about S2 or 3" as shown in the manual. Or is it more complicated than > that? > > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
