Loss of picture with distribution amp

Marky Harvey

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hi

I hope someone can help with this.

I have a labgear ldu608g distribution amp installed in my loft. It takes feeds from 2 sky lnb inputs and from an amplified terrestrial input. I have a sky+ HD box with an io link connected to the din socket and a magic eye in a remote room. Rather than combine the terrestrial signal using the TV outlet at this point, the installer used a combiner connected just before the uplink is connected into the distribution amp.

All worked fine until last week when I lost the satellite picture, not the sound, from the remote room. The terrestrial signal was still fine. I disconnected the combiner from the uplink cable in the loft and put the uplink cable directly into the uplink socket. This restored the satellite picture in the remote room. I then tried to combine the terrestrial signal by connecting the TV out on the master wall plate into the rf in on the io link on the satellite receiver as shown in the installation diagram. As soon as I do this, I lose the sky signal from the remote room, just like the initial problem.

I can't work out whether I have a hardware failure of the distribution amp or io link or some other problem.

Any ideas please?

Thanks
 
How do I do that, and why would I suddenly need to change?

Thanks

And is there a particular channel to change it to?

Thanks

Hi

I managed to change the rf output channel but still the same problem.

Thanks

Mark
 
Last edited by a moderator:
What rf channels have you tried, if it's on the top end you could have new 4G on there now but which channels are best depends on the area & it's local bands & any local interference etc..

also, that rf amp has a cctv input which is basically a second rf so you could put your aerial in the CCTV input & the sky rf modulated output in the main rf / aerial in (marked UHF IN 12v) without a combiner & properly maintain magic eye functionality.

also 2#, the LNB1 IN / OUT are just connected together inside - only LNB2 has diplex sat/ uhf combining to reduce a coax run to the lounge - is 'that' used? it can be switched off to reduce noise.

similar info here
 
Hi

Please can you explain the rf channel thing? Is each of the digital channels eg bbc one on a different rf channel? Does the sky rf out have to be a few channels away from anything else

Thanks
 
Last edited:
Hi

Please can you explain the rf channel thing? Is each of the digital channels eg bbc one on a different rf channel? Does the sky rf out have to be a few channels away from anything else

Thanks

One UHF carrier channel in digital TV carries multiple TV and Radio channels using a process known as multiplexing. Analogue TV requires one UHF carrier per TV channel. Depending on your local TV transmitter you will have a number of these multiplexes (shortened to MUX). The modulator in the Sky box creates a analogue channel using the UHF channel you specify. This must not interfere with the digital mux added to your sky box via the rf in socket. The confusion arises with channel numbers also being used to specify say BBC1-HD on channel 108. More correctly these should be called Logical Channel Numbers (LCN). These are specified by the epg and are not part of the broadcast stream. In this way the same broadcast can have a different channel number on a Sky Box and a Freesat box (Different epgs).

To find what channels your transmitter uses, Google Freeview on xxxxxx (your local transmitter).
 
Hi

Further to my previous post, I tried several more rf output channels and eventually got 61 to work. This was the best picture I could get on any of the channels I tried.

1 question though - why have I had to change rf channel? Everything worked fine on rf out 34 until last Monday morning.

I don't know which transmitter we use, how do I find out?

Thanks
 
Hi

Further to my previous post, I tried several more rf output channels and eventually got 61 to work. This was the best picture I could get on any of the channels I tried.

1 question though - why have I had to change rf channel? Everything worked fine on rf out 34 until last Monday morning.

I don't know which transmitter we use, how do I find out?

Thanks

Enter your details here, at the follow up dialogue tick the detailed reception option. The result will tell you the transmitter and the UHF channels it uses.

http://www.dtg.org.uk/work/coverage.html

There is a possibility that your transmitter may have increased it's output power. If so a simple variable attenuator on the input to the Sky box may work by simply reducing the signal level.

Eg

http://www.ebay.co.uk/itm/VARIABLE-...392?pt=LH_DefaultDomain_3&hash=item5646a27908

Simple test, pull out the aerial connection to rf1 in, now look at the Sky channel on the remote TV. If it's now clear the above is a definite possibility.
 
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1 question though - why have I had to change rf channel? Everything worked fine on rf out 34 until last Monday morning.

It could be your main transmitter or a more distant one that is getting through better for some reason.
It could be some new, very local noise issue, it could be an electrical fault somewhere on your gear causing a noise issue, power wise it could be tiny but enough to produce noise on part of the UHF band.
 
Hi

The signal I'm getting on the remote TV isn't great using channel 61. The transmitter is Hannington. Can anyone recommend whic might be the best channel to use?
 
Hi

The signal I'm getting on the remote TV isn't great using channel 61. The transmitter is Hannington. Can anyone recommend whic might be the best channel to use?

Start at 21 & test each one until you find a clear one- you can't predict 100% which will be clear or the best, there's too many variables - other distant transmitters, second harmonics/ echoes reflections, local rf/em issues etc..

THIS is your transmitter and the channels it uses but you should search that site to see other transmitters that either also cover/ fill in or that might bleed over your area on certain channels
 

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