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Interference

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Interference

Post by Sparks » Fri Jan 01, 2016 5:08 pm

I have noticed of late that my experimental and other MF receivers have developed a crackle along the full tuning range. Today, I wondered if it might be because the aerial insulator was shackled to a short chain going to the mast. I removed the chain, and connected the insulator by a short length of rope. Still get the crackle. My wife commented that her small portable is getting this as well between channels, but it goes if the set is tuned in. I tuned the portable between stations and hunted for the source. I quickly traced it to the main fusebox. I turned off the master switch for a few seconds and the crackle disappeared. I suppose this indicates a slightly bad contact. I switched it on and off a few times to try and clear it, and it does seem a lot better. I would obviously not be allowed to change the switch myself, but wonder if it is an expensive job? Maybe it will settled down of its own accord now I have worked it a few times.
Perhaps it even explains why my PC has been "freezing" from time to time? Anyone else come across this?
Bob

 
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Re: Interference

Post by Niall » Fri Jan 01, 2016 5:52 pm

Because the main switch turns off everything, that doesn't prove it is at fault. Did you try pulling fuses / opening breakers to see if the fault could be isolated to any particular circuit? It could be a bad connection on any circuit or an appliance connected to it.

 
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Re: Interference

Post by Hartley118 » Fri Jan 01, 2016 5:54 pm

I've noticed the new rhythmic crackle too, particularly around the 200m end of the MW band, and I'm blaming flickering Christmas lights. I've checked that it's not mine!

All I can suggest is that we wait till 12th night and see whether it stops.

Martin

 
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Re: Interference

Post by Sparks » Fri Jan 01, 2016 6:59 pm

I did flick them off one by one, but it seemed to be the main switch that cured it. Anyway, it seems to have gone now, so it may just have been contacts in one of them getting a bit dirty through lack of use. I will see how it is tomorrow.
Bob

 
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Location: Lancashire

Re: Interference

Post by Sparks » Sat Jan 02, 2016 10:25 pm

I think I am getting closer to a solution. Thinking about it, I feel sure it started when I altered the run of my aerial, taking it past the main power box situated behing a wooden door on the outside of the house. My wife's small transistor set is standing on the window ledge only about three feet from the power switchboard. I will try re-routing my aerial the other way when the weather gets a bit better!
Bob

 
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Location: Lancashire

Re: Interference

Post by Sparks » Tue Jan 05, 2016 6:03 pm

Whatever I did, I could not find the problem. The nearest I got was that it stopped when I turned the power sockets breaker off! In the end, I gave up, just hoping it would go away. Eventually, the continuous torrential rain stopped, and so did the intereference! Maybe it was something to do with the high voltage pilons about half a mile away getting wet. Don't really know, but it will be interesting to see if it comes back when the rain starts again.
Bob

 
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Re: Interference

Post by Niall » Tue Jan 05, 2016 6:27 pm

Might be worth checking all the plugs in use on that ring for heat, loose terminal screws, slack fuseholders and signs of arcing on the pins.

Last time I had something like this it was in a bedroom, faint buzzing could be heard in the dead of night. Turned out to be a plug on an extension lead - the screw on the live terminal had worked loose.

 
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Re: Interference

Post by Sparks » Sat Jan 09, 2016 6:42 pm

The crackling continued intermittently until the 12th night. Then, they all turned their Christmas tree, and house decoration lights off, and it stopped as Martin suggested it might. I would never have thought of that! I think it must have been coming along the mains into the house, although the battery sets were picking it up when near any wiring.
Bob

 
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Re: Interference

Post by Hartley118 » Sat Jan 09, 2016 11:38 pm

Frustrating isn't it - especially to those of us who've in the past spent blood, sweat & tears getting products to meet tight European EMC specs in order to be able to affix that all-important CE mark.

It does seem that there's one rule for responsible European companies and another much easier set of criteria for our competing Far Eastern manufacturers that actually make most of the products we buy. :cch

Martin


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