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Bad Freeview reception when it rains


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Old 21-08-2008, 15:18
ptm1
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Is it a know problem that when it rains that it interferes with digital broadcasts?If so is there anything that can be done about it?
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Old 21-08-2008, 16:14
radioredcat
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Hi, I sounds like your reception could be borderline,But there is a lot of work going on around the country so your transmitter might be on reduced power have a look here.

http://www.ukfree.tv/txlist.php#

Also trees can cause this kind of problem,loft aerials also when the roof gets wet signals can be defracted differently as to when it's dry,but under these circumstances it does point to a marginal signal.


andy
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Old 21-08-2008, 16:46
chrisjr
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It might also be your aerial. If it is outside and getting on a bit then the waterproofing of the terminal block could be compromised.

That could let water seep in which will change the characteristics of the aerial to a degree and lead to corrosion of the terminals. Both of which can and probably will degrade the signal. Also if you use old air spaced coax cable the water can get into the air spaces further degrading the signal.

The solution is to get up there and have a good look. If the aerial terminals are blackend and covered in gunge then that is the problem. The solution is more than likely a replacement aerial and if you are using old coax get that upgraded to more modern satellite grade cable at the same time.

But your aerial doesn't have to be waterlogged to suffer in the rain. If your reception is borderline at the best of times then rain can tip it over the edge. Trouble with digital is that it doesn't degrade like analogue.

With analogue as the signal worsens so does the picture. With digital the pictures can stay perfect as the signal degrades. You then reach a point where the error correction can't paper over the cracks anymore and you get break-up. Then it just goes altogether. And the difference between break-up and it vanishing can be quite small.

So you may still need to check your aerial. Make sure it is suitable for receiving digital (which is NOT the same as having a digital aerial). ie it covers the channels used properly and has sufficient gain to receive a decent signal, bearing in mind digital is transmitted at lower power than analogue.

And make sure it's still pointing in the right direction! And the screws in the cable connectors are nice and tight still. Look out for stray strands of the outer screen braid that may have worked loose and be touching the inner conductor or terminal. All that can affect signal strength.
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Old 21-08-2008, 17:35
albertd
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It might also be your aerial. If it is outside and getting on a bit then the waterproofing of the terminal block could be compromised.
Or if it was like mine, the cover could have vanished completely. (Thanks pigeons - probably )
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Old 21-08-2008, 18:14
Sam Radford.
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Use elbow grease: http://satcure.net/tech/silicone.htm#dish
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Old 09-09-2008, 10:44
mbanbrook
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I lose channels in the upper channel multiplex numbers when it rains (60, 63, etc), and there's usually a bit of delay of up to 15-30 mins in losing them from when the heavens open. Other multiplexes are OK.

Any ideas on what this might be? Thanks in advance.
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Old 09-09-2008, 12:35
Ray Cathode
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Poor reception when it rains, as has been said already, indicates MARGINAL reception. The cure is to increase the aerial gain, either with a better aerial or an amplifier. Water if it gets in the cable and aerial will stay there and permanently degrade the signal.
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Old 09-09-2008, 17:36
Sam Radford.
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Often caused by wet leaves in the signal path. It takes some time for the rain to penetrate a tree so you'll see reception get steadily worse over a period of half an hour or more. And recovery will take some time, too.
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Old 09-09-2008, 23:01
mbanbrook
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Often caused by wet leaves in the signal path. It takes some time for the rain to penetrate a tree so you'll see reception get steadily worse over a period of half an hour or more. And recovery will take some time, too.
That makes sense - there's a few trees en route to the transmitter, and my new crap-o-rama Top Up TV box can't be tuned manually to stronger multiplexes for a few channels. Thanks for all your advice!
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Old 09-09-2008, 23:38
radioredcat
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Often caused by wet leaves in the signal path. It takes some time for the rain to penetrate a tree so you'll see reception get steadily worse over a period of half an hour or more. And recovery will take some time, too.
I concur with what sam has said i don't think there's anything worse than trees for uhf reception and even quite a distance away they affect the way the signal is propagated at least buildings are still but trees are moving all the time.


andy
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Old 10-09-2008, 08:29
N.Dean
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I concur with what sam has said i don't think there's anything worse than trees for uhf reception and even quite a distance away they affect the way the signal is propagated at least buildings are still but trees are moving all the time.


andy

I remember a similar problem from my childhood. We lived on a hill in Oxfordshire. The old VHF TV aerials pointed east ( to crystal palace ) and north ( to Lichfield ) and worked fine.
When a UHF aerial was installed, for the Oxford transmitter, the elm trees to the north east blocked the UHF signal. This happened when the leaves were wet or when the sap was rising. The solution was to move the UHF aerial from the roof to the front garden ( on a 6ft pole ), thus receiving the signal under ther trees.
The trees were later felled due to dutch elm.
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Old 16-09-2008, 21:12
Mosie
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I had the same problem, the fault was with the ariel, water was getting into the terminal box on the ariel.

I had to replace all of the coaxial cable and seal the lid of the terminal box with silicone, it works fine now.

cheers Mosie
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Old 18-09-2008, 15:21
Pop Roberts
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I had the same problem, the fault was with the ariel, water was getting into the terminal box on the ariel.

I had to replace all of the coaxial cable and seal the lid of the terminal box with silicone, it works fine now.
Likewise, but with me the problem was a split in the terminal box cover (on a Blake DMX10). Found today as I was doing some refurbishment work on the aerial system, and the aerial wasn't very old, only about 2 years. I've just reported the problem to Blake so it will be interesting to see what they say. Meantime, that aerial is down and replaced with a Log Periodic with new feeder, which is ok but the signal a bit lower than the Blake (even with the wet coax!).

Pop
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Old 18-09-2008, 18:30
StoppingService
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my new crap-o-rama Top Up TV box can't be tuned manually to stronger multiplexes for a few channels. Thanks for all your advice!
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Old 18-09-2008, 20:09
Sam Radford.
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Likewise, but with me the problem was a split in the terminal box cover (on a Blake DMX10). Found today as I was doing some refurbishment work on the aerial system, and the aerial wasn't very old, only about 2 years. I've just reported the problem to Blake so it will be interesting to see what they say.
They'll probably say that you should have wrapped it with self-amalg tape as described here:
http://www.satcure.co.uk/tech/silicone.htm#dish


Unfortunately, modern aerials no longer use Bakelite covers. They use cheap thermoplastic which has poor UV resistance.
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