[Elecraft] P3 as a phase noise measurement tool

[Jim Brown]

On 6/7/2022 8:04 AM, Dave (NK7Z) wrote:
> Thanks in advance for any help in this...

I use a P3/SVGA to measure signal bandwidth (and before I had the SVGA 
board, used the P3). It's dynamic range is 100 dB, but the screen can 
display only 80 dB. A rig with decent phase noise performance is well 
below that.

See http://k9yc.com/TXNoise.pdf  which compiles measurements done in 
ARRL Labs. The plotted data are ARRL measurements in electronic form for 
a dozen or so rigs, re-plotted on the same graph. I did this work in 
2014; it was motivated in part by complaints by WRTC participants, and 
the rigs chosen were those they used, and other mainstream rigs popular 
at the time.

Phase noise from a CW signal is heard as a "whooshing" sound away from 
the signal, and is what makes cheap rigs unwelcome on Field Day. It 
extends hundreds of kHz away from the transmitter frequency. It's also 
present, of course, on SSB and digital modes, and is also present in 
receive.

This was a LOT of work that required a lot of cooperation with ARRL 
Labs, and I have no interest in re-doing it for today's rigs.

73, Jim K9YC