[Elecraft] K3 S-Meter and Noise

[Jan Erik Holm]

I have noticed this on my K3 also. Compared to my FT-1000D
it´s much noisier. As far as I understand the MDS of the
K3 is around 134 dBm, I have measured my FT-1000D to about
141 dBm I think it was. My feeling is that something isn´t
right with the K3 but I simply haven´t had time to persue
it.

/ Jim SM2EKM
----------------
Dave G4AON wrote:
> I have a feeling something may have changed in later K3 firmware,
> possibly as a result of calibrating the receiver gain via the K3
> Utility. Previously I have been able to calibrate the S-Meter from
> around S6 to S9 +60 and have it almost perfect, now it doesn't seem to
> be possible to get it that good.
> 
> Anyway, these are actual measured results from my K3, which is using the
> latest pre-release beta firmware (v3.41). These measurements seem OK to
> me and the K3 doesn't seem any noisier than other radios on my 80m
> dipole. The S-Meter has been calibrated without the pre-amp in use. It
> is quite hard to set it correctly all the way from S1 to S9 +60... AGC
> set to default values. SMTR OFF = 027, SMTR SC = 010, SMTR PK = OFF and
> SMTR MD = ABS (the latter makes no difference to the S-Meter readings
> below).
> 
> S1 is solid at -115 dBm, S2 is solid at -109 dBm and S3 is solid at -105
> dBm. These are using CW with the pre-amp off on 80m, 2800 Hz filter.
> There is about 1 S-point drop using either the 400 Hz or 250 Hz filter.
> 
> MDS (3 dB SINAD) is -135 dBm in a 400 Hz bandwidth with the 2800 Hz
> filter, pre-amp off. An input of -126 dBm gives 10 dB SINAD for the same
> settings. SINAD is signal to noise and distortion.
> 
> The K3 is sensitive enough on the lower bands to not need the pre-amp,
> which of course would give rise to higher noise levels.
> 
> 73 Dave, G4AON
> K3/100 #80
>