[K6BW] White noise question

[Steve Johnson]

Hi 
I have a white noise question. I am running a 20 meter flat top dipole next
to the side of my building at 12 feet. The last 3 days I have only been
hearing S-7 white noise on 20 meters. When I switch down to 30, 40 and 80,
the white noise drops to a normal level between S-1 and S-3. When I switch
up to 17 the white noise drops to S-3 to S-5. When I switch up to 15 it
stays at S-3 and when I switch up to 12 it stays at S-3 and when I switch up
to 10/10 it stays at S-3. The reception of signal on 30, 40 and 75/80 has
been fine. I am open for any comments or suggestions.

Thank you,
Steve