Finding HF noise in your QTH

What use is an F-call? Over the past month or so I've had some limited HF capability at my QTH in the form of a wire loop that runs around the ceiling in my office. It's not pretty and it doesn't really work that well. Across most bands, most of the time, I find an S8 or S9+ noise floor which makes hearing other stations a challenge. I've been at a loss to determine what's going on. I was discussing my plight with some amateurs over lunch one day and someone hit on the idea that I might see if I could determine the source of the noise by way of elimination. So, with that in mind, I plugged my radio into my battery pack, as if I was portable, and then went to the meter box and turned off the house power. Back to the radio and at first I thought the battery had run out, but no, the radio was fine, the battery was at 12.5V and everything was working. One thing was missing, the noise. I used my now quiet radio to have a look across the bands and found all manner of activity. I settled on a CW signal, turned up the volume and then went back to the meter box. One switch at a time, I switched stuff back on. When I heard noise, I switched it off and moved to the next switch. By doing this, I located two fuse groups that had noisy stuff on them. One of them was the ducted air conditioning system, the other was a generic power circuit. By switching everything else off, and just the noisy power circuit, I could walk around the house looking for things that were still on. One at a time I would switch them off at the wall and low and behold, the biggest culprit was the little power supply for my ADSL modem, the one that had blown up twice before and by the sound of it was creating a veritable HF storm on my radio. So, now I can replace the power supply for my modem, and when I want to play on HF, I can turn off the air conditioner and actually hear the remote station. At some point I'll have to figure out if it really is the air conditioner, or just one of a few things on that circuit, but I'm a lot closer to HF bliss. All I need now is some contacts. I'm Onno VK6FLAB