[Elecraft] P3 as a phase noise measurement tool

[Wes]

I can't answer the first two and Al has given the answer to the third.

But, you're not going to be measuring phase noise in the strictest sense, but 
what ARRL calls composite-noise.  Interesting they *do* actually measure phase 
noise with an HP11848 Phase noise test set and then they assume that phase noise 
dominates AM noise and call it composite.  Go figure.

Today, everyone calls single-sided noise "phase noise" for the same reason, but 
it needs to be remembered this noise is due to phase fluctuations in the device 
under test (DUT).  But...what you measure are the results of phase fluctuations 
in the DUT *plus* the phase fluctuations in the measurement system's oscillators 
and/or sampling clock jitter.  This is the K3/P3.

Wes  N7WS


References:

https://www.ab4oj.com/test/docs/rs_pn2015.pdf

http://www.ke5fx.com/phase_noise.pdf  (I used to work with Terry Decker, one of 
the authors of this)


On 6/7/2022 8:04 AM, Dave (NK7Z) wrote:
> Hi,
>
> I am contemplating practicing some phase noise measurements using a P3. If I 
> correctly understand the measurement, (which I may not), I should express the 
> result, using db down from peak, so many Hz away from peak, using a 1 Hz width.
>
> First question; is the above correct?
>
> Second question; (amusing Q1 is correct), what is the pixel width of the P3, 
> and can I just divide that width by total frequency spread shown on the P3, 
> and assume that number I get is correct for width per pixel in Hz?
>
> Third question, (assuming Q2 is correct), once I get a number from question 2, 
> can I then just divide that result by X, where X is selected to bring the 
> width of measurement to 1 Hz?
>
> Thanks in advance for any help in this...
>