[Elecraft] P3 Phase noise/HighSignal Response?

[Jim Brown]

Hi Dave,

The P3 is quite good for measurements, and the SVGA card is even 
better.  Here's a collection of work I've done with whatever rigs and 
amps I could get my hands on to measure.

http://k9yc.com/P3_Spectrum_Measurements.pdf

In my experience, if you keep the K3 within its linear region, you'll 
get good data from the P3 if you understand the measurements you're 
making.  Limitations -- the dynamic range is 100 dB, but you can only 
display 80 dB on screen. For all of the operation I do, I use the P3 
with a lot of averaging and a slow waterfall, fairly large waterfall.  
For measurements, I use the P3 in Peak reading mode and let it 
accumulate peaks for a while. I make the amplitude display pretty large, 
set it for 80 dB, and adjust levels to fill the amplitude screen.

When I'm checking CW bandwidth, I send a series of dits in the range of 
35 WPM for at least 20 seconds I reset the peak a second or so after 
I've started sending dits so I don't see any initial transient that 
might be present. Notice that I set the span for a fairly narrow bandwidth.

The annotations you see for bandwidth are obtained by moving the cursor 
to each data point and writing down the readings, and they are the 
DIFFERENCE between the high and low points.

If you want to show data more than 80 dB below the peak of the signal, 
you can repeat the measurement with the reference level reduced by 20 
dB.  More than that and the P3 will overload.

73, Jim K9YC

On Mon,3/13/2017 6:03 PM, K5MWR via Elecraft wrote:
> I am trying to use my P3 to evaluate signals from other hams here in 
> my community.  While I know the K3s is excellent, I am not sure what 
> to expect out of the P3 in terms of phase noise or response under high 
> signal conditions.  I can always pad to lower the signal but that will 
> not help with any P3 internal phase.