I noticed a LOT of noise from two different switching supplies that went away after going back to a linear. Don't think I'm too close to my antenna, either.
What linear did you choose?
I have a Astron SS30 and it works fine with no noise. My plasma TV generates all the noise. My tower is 50ft+ away with the hex up 35ft. My BigIR is 30ft away and both don't pick up noise from the switcher.