[Elecraft] P3 as a phase noise measurement tool

[Dave (NK7Z)]

Al,
THANK YOU!!!!  Also, thanks for the formula!  :)

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 6/7/22 08:18, Al Lorona wrote:
> According to Al, N1AL, "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."
> 
> To "convert" or "correct" to a 1 Hz bandwidth, use the formula:
> 
> BW_correction_factor = 10 * log(P3_effective_BW)
> 
> For instance, to "convert" a 100 Hz effective P3 bandwidth to 1 Hz, the factor would be 20 dB. So, if you measured a noise level of -80 dBm on the P3 whose effective bandwidth were 100 Hz, that would really be -100 dBm in a 1 Hz bandwidth.
> 
> Al  W6LX/4
> 
> 
> 
> 
> On Tuesday, June 7, 2022, 11:06:05 AM EDT, Dave (NK7Z) <dave at nk7z.net> 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...
>