Responding to Wayne B.
Are you running the power brick from a small inverter?

No. At the moment It's hooked directly to shore power. In the past, while
underway I've used a small Radio Shack inverter and you are correct, this is
noisy enough to be a small problem with VHF. Have not tried it yet with the
SSB.

If so, that is
more likely to be the noise source in my experience. Try running the
laptop on shore power while at a dock and see if you have the same
problem. If not, consider getting a better inverter. My Xantrex
Prosine generates very little RF noise compared to the small modified
sine wave units.

I have a Xantrex 20A charger and yes, it is surprisingly quiet - can barely
detect the difference between on & off when listening to the SSB.

Scott