"AndyS" wrote in news:1169524019.256493.196630
@a75g2000cwd.googlegroups.com:

working just fine...... At HF, it isn't unusual to have 30uv/m of
"noise", from cosmic or galactic or whatever... A 20 db noise
figure is just fine for a receiver in those ranges...... The biggest
challenge is man-made interference ......


Dan,

Some more information on expected ambient noise per ITU-R p.372-8 is in my
article at http://www.vk1od.net/fsm/FSAmbientNoise.htm . For 3.6MHz, it is
probably wise to expect ambient noise field strength somewhere around
6dBuV/m in 2kHz bandwidth in a residential environment. If an antenna can
develop more than about -130dBm in the receiver from that field strength,
the S/N should be ok on most modern SSB receivers which have a noise floor
somewhere around -136dBm. If you were in a quieter environment, you would
benefit from a better antenna.

Owen