"From an old computer monitor"
What else has this network built in, would a PC power supply? Don't have any PC monitors sitting around to cannibilize but plenty of other junk. I definitely have noticed that line powered radios have much worse buzz than transformer operated radios. Some of my AA5s are almost
Unusable these days.
EDIT
To answer my own question, I looked at things like this
http://www.smpspowersupply.com/ATX_p..._schematic.pdf
If the junk atx supply I have has such an input filter there's a Crosley which will be receiving some surgery tonight.