[Elecraft] K3S IMD Questions

[Jim Brown]

On Mon,8/31/2015 10:04 AM, Yngvi (TF3Y) wrote:
> Even though I'm personally most interested in CW I wonder if there is 
> any recent two tone SSB tests that's been published?

I've published some SSB bandwidth measurements using pink noise as 
excitation. Because pink noise contains all frequencies, the spectra 
resembles music and speech, and is dynamic, it excites IMD in a manner 
comparable to speech.

http://k9yc.com/P3_Spectrum_Measurements.pdf

http://k9yc.com/FTDX5000_Report.pdf

So far, I've measured only a few rigs using pink noise, but of those 
I've measured, I've seen very little difference between them.

On the air is a very different story -- it's VERY common to see 
distortion on SSB signals in the form of both upper and lower sidebands 
on audio peaks. Because it is present in both sidebands, I strongly 
suspect it's caused by power amps that are over-driven, or poorly tuned, 
or improperly biased. We hear it as splatter (sometimes as wide as 10-20 
kHz), and see it on the P3 and horizontal lines corresponding to audio 
peaks.

73, Jim K9YC