Didn't want to hijack the Code Wheel  thread...However:  Interesting RFI paper Steve - Thanks...

Just for fun I just tuned my HF receiver from 7.0 to 8.0 mc.  Located in Suburbia, low halfwave dipole, noise floor at quiet freqs about S2 at 1315 Local.

I counted 24 hashy, fairly broad noise sources in that band that showed above S4, there were many other weaker ones.  You can even see their presence on some remotely located SDR sites that were picked as to be "quiet".  You can watch them drift around in the waterfall tuning ranges...Probably local to the antenna.

Since I work 40 CW fairly often I find these things drift around and invariably land on that weak CW op I am trying to work. They then drift away after a minute or so.

Since our ((not)great) power utility power company fails pretty often around here I get a chance to scan the bands while the neighborhood is "out" using battery powered receivers - very quiet.  I did find a bad wall wart in my own house that way - it powered a USB gizmo.  Replaced, S9 noise gone from that one; gave it a new attitude with a ball peen hammer...

Anyway my $ 0.02

Thanks, Tim

N6CC