Interference from TV

Noise and interference issues?
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Alex Lawler
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Interference from TV

Post by Alex Lawler » 12 Aug 2015 15:39

I decided to poke my Degen out of the lounge window and left it on an empty frequency whilst watching the TV last night. I heard a high pitched sound across the band that went as soon as the TV was turned off and returned immediately it was switched back on. Infact whilst the TV is on the only way to minimise the interference is to walk to the bottom of the garden. This interference has nothing to do with my previous intermittent problems but thought it was interesting enough to post. Incidentally I have a freesat box and Sky mini dish. I'm used to certain lights affecting MW but nothing on FM before.
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Julian Hardstone
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Re: Interference from TV

Post by Julian Hardstone » 12 Aug 2015 19:21

Sounds like it's a Plasma screen - these wipe out everything from VLF to UHF :(

Andrew Webster,Wigan
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Re: Interference from TV

Post by Andrew Webster,Wigan » 12 Aug 2015 20:00

What make and model is the TV as Julian said Plasma TV are the worst for QRM problems but TV's with failing capacitors can also cause QRM.

Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

Alex Lawler
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Re: Interference from TV

Post by Alex Lawler » 12 Aug 2015 20:07

My girlfriend won't let me get near the TV as it's bake-off. However I know it's Hitachi and is probably Plasma. It's not a problem as I just make sure it's off when dxing. I hadn't realised this was a common problem. Dxing is getting harder and harder these days with so much interference potentially across every band from things that I would never naturally attribute to causing interference. How does a TV manage to obliterate every band two frequency that doesn't have a local on it. :roll:
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Re: Interference from TV

Post by Julian Hardstone » 12 Aug 2015 20:28

Europe is set to permit cordless power charging on VLF, which should clear LW/MW of those pesky broadcasters

daveB
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Re: Interference from TV

Post by daveB » 12 Aug 2015 23:45

Infact whilst the TV is on the only way to minimise the interference is to walk to the bottom of the garden.
That is why a couple of years ago I decide to try putting an aerial at the bottom of the garden. It made suchandifference compared to the one at the back of the house that I upgraded it to a 5 ele yagi on a rotator. It only reaches 18.5 ft but is very effective.
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

Alex Cator
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Re: Interference from TV

Post by Alex Cator » 13 Aug 2015 22:39

I have an aerial a long way from my house too, which is a Triax FM3. Mine is on what was a washing line pole, about three metres above the ground. I used to get noise on 106.7 MHz a long time ago pointing a particular way, blocking Eins Live from Langenberg, but I luckily don't have to cope with noise anymore unless I am listening to vertical stations, which requires the indoor Philex ribbon wire antenna to receive because the FM3 is horizontal. The Philex ribbon wire antenna picks up noise from the family LG 47LA640V smart television set when my parents watch the television, which normally happens in the evenings. It isn't too bad, as it's only an LCD/LED TV, not a plasma. I hope to have a vertical FM3 too, aimed at Holland. Maybe a vertical dipole would be better, so I can hear Irish signals and the French locals too?

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Tim Bucknall
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Re: Interference from TV

Post by Tim Bucknall » 14 Aug 2015 12:56

I noticed a decrease in plasma screen qrm on 1521khz, MW is still destroyed beyond hope in urban areas
so it doesn't really help me, but they're falling out of fashion

re: Irish in East Harling, if the following freqs were free for you it might be worth trying a vertical, but I bet they're not:
89.1,91.3,93.5,98.7,100.9 - presumably blocked by Wrotham?
89.6,91.8,94.0,99.2,101.4 - presumably blocked by tacolneston?
maybe you can still try 87.8
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Andrew Webster,Wigan
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Re: Interference from TV

Post by Andrew Webster,Wigan » 14 Aug 2015 20:06

Alex Lawler wrote:How does a TV manage to obliterate every band two frequency that doesn't have a local on it.
Anything electronic can cause QRM not just TV's but Plasma as said are the worst culprits although but I did repair an old 50" LG and nothing from it my neighbour has a LG Plamsa and it filled me with dread when I saw that being delivered but nothing from that either yet.

Usually it's the cheap stuff that cause QRM PSUs were filtering is non existent are the worst and also fire starters especially the fakes also as components start to fail that can also be a cause.
So in a nutshell it's pot luck whether equipment causes QRM but there are many variables to this.

Andy
Receiving equipment: 2 Sony ST-S311, 1 Sony ST-SE520, 1 Sony ST-SE700 2 crossed FM 5s rotatable, 1 homemade FM 3 horizontal beaming S/E, 1 vertical FM 3 fixed beaming at Ireland, 2 element band 1.

Alex Cator
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Re: Interference from TV

Post by Alex Cator » 11 Sep 2015 21:54

Tim Bucknall wrote: re: Irish in East Harling, if the following freqs were free for you it might be worth trying a vertical, but I bet they're not:
89.1,91.3,93.5,98.7,100.9 - presumably blocked by Wrotham?
89.6,91.8,94.0,99.2,101.4 - presumably blocked by tacolneston?
maybe you can still try 87.8
The Mount Leinster ones are definitely blocked by Tacolneston, so you are right. Tacolneston is my strongest transmitter and it is the strongest pain in the neck I have to contend with.
Considering how easy it is to null Wrotham if I point away, I'm sure Kippure would be possible via tropo. I have yet to try 98.7 and 87.8, although I tried 98.7 before I knew Ireland was vertical and I got nothing. I have received BNR Nieuwsradio from Rotterdam via scatter on 91.3 in a particular direction, so definitely Kippure should be okay. So should 87.8 Clermont Carn! :D

Alex
Home: Sony ST-SB920 (modified), Sony XDR-S10HDiP, Onkyo T-4970, Ford 5000 RDS, horizontal Triax FM3
Mobile: Ford Fiesta (Style, 2013) and Ford Focus (2012) car radios
Portable: Tecsun PL-390, Grundig G5 (2 x 110kHz), Etón G8

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