After having a successful setup of the radio shack over the weekend, I took the HF rig to the local radio club, but when I returned, and plugged everything back in, BUZZZZZZZZZ. S20 over 9 noise. not good.

Troubleshooting kicked in. Whats changed? Earlier in the afternoon I had put up the 6m dipole antenna and finished working on installing an earthing stake and earth wires back to the rig. By process of elimination, I removed each. Noise still there.
It was late in the night by this point so I made an assumption that the noise was in fact being caused by nearby power lines having damp insulators, so went to bed with the though of investigating the issue if it existed the following day. Yes, it did exist the following day.

Given that it sounded like 50Hz buzz from AC power, I set about doing some radio direction finding using my handheld radio, and was somewhat appalled to find that the signal extended a significant distance in every direction.  At this point I decided it was time to see if the source was local to my house or indeed offsite. If it was offsite, it would probably be time to lodge a complaint with the ACMA.
Shut down most electrical things in the house. Still had noise. Flipped the main circuit breaker, the buzzing abruptly stopped on my handheld. Hmmmm. Started powering circuits back up and when I powered on the “Lounge and Kitchen” the buzzing took off where it stopped. Well, at least I had that narrowed down to 1) being local to my home and 2) on a particular circuit.
It is worth pointing out this is one of 2 “old” power circuits in the house, and saying it is “Lounge and Kitchen” is a bit of a misnomer – it is the power circuit for everything that does not have a specific, known circuit. This includes the room my radio shack is in.
I unplugged everything in the room. No noise. One by one I started added power back to devices until finally I plugged in the LCD monitor for the shack computer and suddenly the noise was back. I had found the culprit.
Whilst still working fine as a monitor, this 11 year old monitor had somehow developed a fault which was generating a lot of RFI. Whilst I think it’s something that a good blow out with an air duster could fix, this monitor is difficult to disassemble and is just not worth the amount of effort to attempt repairing.
I guess this means I will be repurposing a laptop sooner than expected for my radio shack.