UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - MW hum - higher frequencies only

agardiner · 25th Jun 2021, 4:28 pm

Thanks for the ideas. It certainly isn't a switch mode in my house, but cannot rule out the neighbour of course. However - I live on a rural estate with very few properties and only one immediate neighbour.

What it could be therefore, is the estate has a working farm, and their repair/maintenance workshops are on the same power lines and only a few hundred metres away. They also have 3 phase supply to them and plenty of air conditioning units, motors etc. I think this is probably the most likely cause of the interference, and then it is being brought in on the 'balanced' power lines and radiated from the ring main!

Fortunate that it is only on the top of the MW band. Lower down is nice and clear, and being rural, no problem at all with SW.

25th Jun 2021, 4:28 pm	#18
agardiner Octode Join Date: Sep 2020 Location: Thetford, Norfolk, UK. Posts: 1,743	Re: MW hum - higher frequencies only - 200Hz Thanks for the ideas. It certainly isn't a switch mode in my house, but cannot rule out the neighbour of course. However - I live on a rural estate with very few properties and only one immediate neighbour. What it could be therefore, is the estate has a working farm, and their repair/maintenance workshops are on the same power lines and only a few hundred metres away. They also have 3 phase supply to them and plenty of air conditioning units, motors etc. I think this is probably the most likely cause of the interference, and then it is being brought in on the 'balanced' power lines and radiated from the ring main! Fortunate that it is only on the top of the MW band. Lower down is nice and clear, and being rural, no problem at all with SW.