[Not] Living with 6m/50MHz interference!

Two halogen down lights (August 2009-September 2010)

August 2009: For weeks I found I had a s8 to 9 hash across the whole of 6m when beaming 130 degrees. It seemed to mainly come on in the evenings so I suspected lighting of some sort, television or computer.

I left it for a bit hoping that it would go away but unfortunately it didn't.

I called Mike, G6HOU, for help and grabbed my FT-847 set to AM mode and my trusty HB9CV. Because of where the noise was coming from was quite definable, a quick use of Google Earth and a compass pointed to one or two houses where the noise could originate.

Walking down the road, turning the antenna as we went, we quickly found that indeed the noise originated in one of the two houses identified. It was dark so I decided to wait until the following day to knock on the door.

The offending 'electronic' transformer

The next afternoon I returned and banged the front door knocker which was promptly opened by the owner. I explained once again about why I was visiting - strong interference - tracking to your house - arcing somewhere - potential fire hazard etc etc. I asked whether I could come back when the noise was on with my radio and my small detection antenna and go round the house and he said that would be fine.

The same night the noise came on and down I trotted. As soon as I got to the front door I noticed a strong buzz on the 847. Going round the ground floor the buzz seemed to emanate from all the power sockets and was strongest next to a door on the ground floor. For some reason the owner was reluctant to let me into a particular room or go upstairs. I think he still didn't quite believe what I was saying. A new strategy was required!

I suggested I go home and call him on the telephone. He would then go to his mains fuse box and turn off each switch in turn while he listened to the noise on the phone. Bingo!

Turning one particular switch off removed the noise and turning it back on again brought it back - even he could hear it! It was the upstairs lighting circuit.

Returning to the house and going upstairs, I found the only light that was on was a halogen down lighter above a bed and this was the cause of the noise. He said that he would call an electrician friend to get the bulb and electronic transformer changed and I went away as a happy 6m operator never hearing it again.

September 2010: Now can you believe it? The very next day after I had got my neighbour's television that was causing me s6 hash sorted out, I turned my antennas to 150 degrees toward Africa. Within 5 minutes, up came an s7 hash that seemed to centre on 130 degrees. I just couldn't believe it. My first thought was to hell with amateur radio as this was just too much!

However, once this thought had passed and sense prevailed once again, I went out with my trusty FT-847 and and HB9CV. Walking down the road it soon became clear that the noise originated from the same house as last year. I returned 10 minutes later, knocked on the door and introduced myself. He looked sheepish and said he would turn the light off. He said that he did have the electrician in but forgot to ask him to change that halogen bulb and transformer. I there and then offered to do it for him which he was fine with.

Upon returning home the noise had disappeared...

The electronic transformers are YT70 dimmable electronic transformers made by Doyle and Tratt Products Ltd.

I just now need to buy a new down lighter and knock, yet again, on the front door. I will buy a 240volt GU10 halogen unit that does not have an 'electronic' transformer!

This is what I did and replaced two bulbs and electronic transformers with two 240 volt halogen bulbs.

Bingo! The noise has disappeared at long last!

I connected the transformer up in my shack and got s9+40 buzz from both transformers on my 847 but I could see anything visibly that would indicate they were faulty though both has CE stamped on them.

I have written a letter to Doyle & Tratt (Varilight UK) as follows as I am interested in finding why these have failed.

"I am a radio amateur and have been having very bad interference on 50MHz. I tracked these down to two YT70 electronic transformers that had been installed in house a long way down my road a few years ago.

I replaced these two transformers with 240 volt halogen units and cured the problem.

I tried these two transformers in my house and they radiate an intolerable amount of 50Hz hash although I cannot see any obvious fault. Clearly these are breaking CE EMC limits.

I am quite keen to find out (as I hope you are) what the problem is with these two units and wondering whether you have the facilities to look at them.

I'd be happy to talk about this and return the units to you if necessary.


Back to home