KC9CDT:
ORION with no NR on = very loud and annoying background
noise...
This is the Digital AGC bringing up the background noise.
Try increasing AGC Threshold and it should decrease. I sometimes
set Threshold to maximum (191.48 uV) under heavy QRN conditions
on 160 meters. AGC is the trickiest thing to learn to use on
Orion IMHO.
73, Bill W4ZV