[Elecraft] P3 Vs. K3 Noise Level

[Alan]

The indicated noise level depends on the receive bandwidth.  For 
example, if you use a narrower bandwidth on the K3, you'll notice that 
the S meter reads lower.

The effective bandwidth of the P3 is approximately one pixel on the 
display, which is SPAN/468.  So, for example, if the span is 47 kHz, the 
effective bandwidth is about 100 Hz.  If the K3 bandwidth is 2.7 kHz, 
then the P3 should read 10 * log (2700/100) = 14 dB lower than the K3. 
14 dB is roughly 3 S-units.

When measuring a steady carrier, the K3 and P3 should read the same, 
since all of the signal is within the bandwidth.  The P3's amplitude can 
be calibrated with the "Lvl Cal" menu selection.

Alan N1AL


On 03/07/2016 03:14 AM, Brian J. Linn wrote:
> All:
>
>
>
> Even after considering the P3 manual (page 21) and with AGC off, I find the
> following difference in S unit measurement odd.
>
>
>
>
>
> Band  P3    K3
>
> 75m   S5    S9
>
> 10m   S0    S2
>
>
>
>
>
> I'm trying to ascertain an accurate noise level reading at my QTH.  Does
> anyone have any thoughts on the degree of difference in these readings?
>
>
>
> Brian KD0HII
>
>
>
>
>
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