Update...The noise goes away completely when I short the ground
counterpoise wire to the antenna. The noise goes down to S3 when I
detach the ground counterpoise wire and leave the antenna connected.
The noise sounds much different between the Midland 79-290 and the
Icom IC-718. On the CB, the sound is like what you would expect a
blank channel to sound - white noise. On the Icom, it sounds like a
buzz that never goes away. I am assuming that this is because the
Midland has "ESP" circuitry which is advertized to kill noise.
Flipper/683