I've mentioned before the RF noise that plagues my location - weird 'nodes' of noise/hash & re-radiated IM all around my suburb that pretty much wipe out the LW/AM/lower SW bands on normal receivers, with one particularly bad 'node' centred around the main switchboard & pay TV distribution boxes for my block that are right underneath one corner of my unit.
And now it's gone.
Well, at least the one downstairs has.
The local power company had our power off for a little while the other day - doing meter testing, according to the guy I spoke to - so I took the opportunity to do what LW DXing I could (not much with a pocket radio inside a brick-&-concrete unit, but there you go…). Picked up the half-dozen or so NDBs & VORs in the region, & the local AMSA DGPS station, and it wasn't until a couple of hours later that I realised the power was back on - but the noise wasn't.
At the same time, the other noise nodes around the suburb have … shifted. A leisurely walk around the suburb with the Tecsun to my ear - I'm sure I looked like someone who spent the 80's with a boom-box on their shoulder, and in middle-age now wanders the streets looking like a racist xenophobic talkback addict - shows that one bad node a couple of corners away is now quiet (but a new one has turned up 50m up the road), and a street that was noisy-but-bearable along its whole length is now clear at one end but gradually increases to terrible as you walk towards the other end. Go figure…
My guess is that the noise has been due poor mains earthing at various locations (here in MEN land, in addition to the distribution earths scattered around the network, every main switchboard / meter box has its own earth connection), aggravated by the power network picking up & conducting / re-radiating the local AM broadcasters (there's several 5-50kW transmitters within 10k or so), and the guy from the power company took the opportunity to fix it when he found it. Fix a poor earth at one place and it solves the local problem - and the change in network earth impedance/path affects other nearby nodes too…
Not to say that everything's perfect - there's still a hum on several AM broadcast stations, which I suspect is due to straight pickup/re-radiation by the mains distribution - but LW & the SW bands from 90M up are clear, and even the 120M SW band is only marginally affected. The most annoying thing is that, just a couple of months after I built a nice tuned loop antenna that successfully 'nulled out' the worst of the noise on our daily-driver AWA 565MA kitchen radio, it's now less effective - because the majority of noise now comes from various other directions… 😖
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