Mike, G6HOU lives with half a mile of my QTH and is also a keen 6m operator. He recently moved to his current location as was instantly faced with severe s9 hash when he put up his antenna. The noise was not on all the time, but it was on for a considerable amount of the day and evening. It never entirely disappeared.
Although, I could not hear the has from my QTH, I would have no doubt that this would contribute to general increase in background noise in my area. It was clear we should have a go at sorting this out!
Mike has identified that the source of the hash was coming from 240 degrees so we plotted the direction on a Google Earth map and identified the road and the possible house quite quickly. So the other evening we took my trusty FT-847 and a hand held HB9CV antenna and walked toward the house we had previously identified...
As soon as we got to the house's garden gate we heard an s4 buzz and a quick twiddle of the antenna showed that the source was the definitely the identified house.
Next day, Mike knocked on the door and explained about the problem, what could cause it and the possible fire hazard an arcing plug or such like could be. He got a receptive response and it was agreed that Mike and I would go back when the noise was on with the 847 but using a small loop antenna this time to specifically identify the cause of the hash inside the house.
The next evening the noise came back. Mike rang the occupant who agreed we could visit and off we went in the rain. We were welcomed in and we could easily hear the buzz on the radio. We tramped from room to another turning off lights, computers, TVs and central heating controllers as we went. The buzz was s9++ at the back of the house but we could not identify any appliance that could be causing it! Oh dear!
We knew that there was an adjoining house (behind the wall) so we suspected that the problem could lay there. The owner knew her neighbours so she offered to take Mike and me around to the house and introduce us - and them to the problem.
They invited us in and we found the noise to be even louder here. We switched off lights and TVs etc but the buzz continued. Eventually, the son of the house mentioned a computer in his bedroom upstairs so up the stairs we all traipsed. As soon as we got to the computer the 847's s-meter went off scale - we had found the source! The owner's son switched the computer off through the keyboard and the noise went away to a great extend. But, when we switched the PC off completely with the power switch on the back of the PC, the has immediately disappeared.
The problem was a cheap Maplin PC switching power supply that was obviously arcing somewhere inside the box. Anyway, the owner and his son were happy as they could see and hear the problem and they agreed to change the PSU as they had built the PC in the fits place anyway.
The owner of the PC eventually changed the PSU and the cause of the problem was obvious. None of the filter components were fitted! All there was in their place were wire links - no wonder it was radiating dire interference!
What was the outcome? Mike said the 6m was absolutely quiet. Success.
Now for the other buzzes coming from other directions! A 6m operator never gets any peace.