According to VK3UM EMEcalc I should be able to measure 3.2dB cold sky to sun noise at the present solar flux intensity, using my terrestrial 0.7dB PGA144MHz masthead preamplifier into my Anglian 2m transverter. The measurements were made using Spectravue in Continuum mode on my SDR-IQ at 28MHz.
I am measuring just on 3dB sun/CS with this system. I think this is pretty good for a single yagi and shows that the claimed gain of the 9 element YU7EF (13.97dBi) is probably pretty close. Of course I cannot be sure of the actual 'cold sky' temperature at this location and this can affect the measured value quite quite strongly. In the non-cold directions sky noise is about 0.5dB higher. It is gratifying that the numbers seem to work out!