>In my view the K3 S meter is simply far too sensitive at the lower end.
Barry, comparing the K3 S-meter to another rig's S-meter will lead you in
circles. Different S-meter standards can be used and calibration between of
the various rigs could be quite different. From my measuring many receivers,
different rigs often agree pretty well at S-9 levels and then they agree at
no place else on the meter. The low end is usually the widest variance in my
experience.
A calibrated signal into the antenna port is needed if you wish to really
know if your S-meter is too sensitive. The K3 then has all the configuration
settings you need to make it right if it isn't. In my case I run S-5 to S-7
background most of the time on 40M with my inverted V (still summer noise up
here). I wondered the same thing about the sensitivity of the K3 S-meter. I
have gone through the effort to calibrate the K3 S-meter using the
configuration settings when I assembled the rig as well as equalized each
installed filter gain to give the identical S-meter readings independent of
bandwidth selected on the K3 front panel.
So I just hooked up my Elecraft XG2 signal generator to I see if anything
has changed from all the different firmware downloads, I read the following:
Off = zero bars
50 uV = S9
1 uV = S3
These reading are about right, band noise right now S-6 with antenna
connected.
If you accept that each S-unit change is 6 dB (you may prefer a different
standard) and S-9 is 50 uV, then 1 uV is 34 dB below 50 uV or 5.66 S-units
below S-9 or S-3.33, S-3 at the resolution of the K3 S-meter.
The Elecraft XG2 is an easy kit to build with maybe 20 through-hole parts if
you want to do this yourself and stop chasing your tail. You will probably
find as I did that the K3 out of the box is pretty much right on with small
variations due to your specific crystal filters you have. It is quite
probable that you now own the most accurate S-meter that you have ever seen
and should start investigating that MP1000.
Mike Scott - AE6WA
Tarzana, CA (DM04 / near LA)
K3-100 #508/ KX1 #1311
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