Satellite LNB - can it be split

Simon

Simon

Simon

Caporegime
Joined
21 Oct 2002
Posts
27,737
Location
Here
Where I live the TV signal is crap.

I have Virgin for the main TV and have been using my old sky plus box in my room with a single cable from the 1xLNB sky dish for watching TV in my bedroom.

A mate has moved in for a few months and the ideal would be to put an old sky box in his room, also from the Sky dish. Can I split the signal to go to each box?

I assume not and I need a twin LNB reciever but any idea would be great

Thanks
 
Also, virgin (not sure if they still do this) send analogue TV signals down the cable as well, so you could just split the cable and plug into the analogue tuner of the TV to get 1-5.
 
You can split the signal from the LNB, but the LNB can only be tuned into a single group of channels at the same time. I think the terminology might be a transponder? Either way, channels are grouped together so you basically each can't watch different channels on different transponders at the same time.
 
daz said:
You can split the signal from the LNB, but the LNB can only be tuned into a single group of channels at the same time. I think the terminology might be a transponder? Either way, channels are grouped together so you basically each can't watch different channels on different transponders at the same time.
Click to expand...

No, the signal from the LNB is polarised, it can only deliver a horizontal or a vertical polarised signal.

A Dual LNB doesn't just split the signal into two signals the same, it outputs the different polarisations on their own output.

This means that once you have this you can split the sat signal further than 2 using sat splitters, as you have all the signals required and not just one or the other


Or potentially I see what you might be saying, you could watch channels if you split the cable and they have the same polarisation. I don't think that would be safe, in terms of the voltages and possible feedback into the STBs?
 
Last edited:
whitecrook said:
No, the signal from the LNB is polarised, it can only deliver a horizontal or a vertical polarised signal.

A Dual LNB doesn't just split the signal into two signals the same, it outputs the different polarisations on their own output.

This means that once you have this you can split the sat signal further than 2 using sat splitters, as you have all the signals required and not just one or the other


Or potentially I see what you might be saying, you could watch channels if you split the cable and they have the same polarisation. I don't think that would be safe, in terms of the voltages and possible feedback into the STBs?
Click to expand...

Polarisation is an attribute of the transponder your tuning to. An LNB can 'see' 4 quadrants which it can tune from, but only locks to one at a time. Dual LNB allows you to lock to 2 quadrants separately.


daz said:
You can split the signal from the LNB, but the LNB can only be tuned into a single group of channels at the same time. I think the terminology might be a transponder? Either way, channels are grouped together so you basically each can't watch different channels on different transponders at the same time.
Click to expand...

Correct. You will need both boxes to be tuned to the same transponder. Its not worth trying.
 
whitecrook said:
Or potentially I see what you might be saying, you could watch channels if you split the cable and they have the same polarisation. I don't think that would be safe, in terms of the voltages and possible feedback into the STBs?
Click to expand...

Even if both the sky boxes were on the same channel it still would not work due to the voltages.

In an LNB that has more than 1 output you don’t have 1 LNB. It is actually multiple LNB's housed in 1 unit.

Every time you change channel the sky box tells the LNB what polarisation and what frequency to search for.

So if you have 2 sky boxes connected to 1 output, and both the sky boxes are on different channels then the LNB will not be able to work out which signal to look for. Even more of an issue will be the fact that with twice the voltage the LNB will simply turn itself off.
 
You need to get yourself a dual or quad LNB to put on the dish if you want to run two Sky boxes independently, they are not that expensive to buy. A Sky+ box usually has 2 feeds from the LNB to allow you to watch and record at the same time but it will work with 1 in a more limited operation.
 
RobH said:
You need to get yourself a dual or quad LNB to put on the dish if you want to run two Sky boxes independently, they are not that expensive to buy. A Sky+ box usually has 2 feeds from the LNB to allow you to watch and record at the same time but it will work with 1 in a more limited operation.
Click to expand...

This is the plan, however I understand you need a different viewing card to record programs ?

It seems that way as when I try to bring up the planner, it won't let me?
 
So if I wanted to use 2 boxes (not +, just one cable) I should use a dual lnb. That is fine that is what I have done before.

If I wanted to use more than 2 boxes I could either feed both into a splitter (switch) and then a feed out to each box OR use a QuadLNB (if the number of boxes was less than 4)

Or to use more than 2 boxes does one need a quadlnb in order to supply 'each quadrant' of the signal independantly?


And so for 2 (freesat+, sky+)boxes, it's essentialy just the same as having 4 boxes.?

cheers
 
I'd be tempted to over spec and put up a Quad or Octo LNB tbh.

I used a Octo when installing Satellite at home. There's only four of the LNB ports currently wired to wallplates (and only one of those has a tuner plugged into it) but with all the faff of getting it correctly aligned (to the right satellite :rolleyes:) with 10 Quality and 10 Strength I didn't like the idea of ever having to do it again when replacing the LNB!
 
Will I need to adjust the satelitte direction? I assume I would just swap the the single to a dual LNB.
 
whitecrook said:
So if I wanted to use 2 boxes (not +, just one cable) I should use a dual lnb. That is fine that is what I have done before.

If I wanted to use more than 2 boxes I could either feed both into a splitter (switch) and then a feed out to each box OR use a QuadLNB (if the number of boxes was less than 4)

Or to use more than 2 boxes does one need a quadlnb in order to supply 'each quadrant' of the signal independantly?


And so for 2 (freesat+, sky+)boxes, it's essentialy just the same as having 4 boxes.?

cheers
Click to expand...

Depends how you want them to work.

If you want sky+ (recording) then you will need two seperate cables from the dish to the box. So two sky+ boxes need four seperate cables.

You cant split the cable, it wont work. The only way is with an MDU system where you have 4 cables from the dish (a different type of LNB is used to take VH, VL, HH and HL down seperaye cables) that are mixed together in the MDU system to provide multiple outputs. This is also quite expensive and not that easy to do.
 
Simon said:
Will I need to adjust the satelitte direction? I assume I would just swap the the single to a dual LNB.
Click to expand...

As long as you are careful when replacing to LNB then it should be ok.

You will need to make sure that the LNB that you get is compatible with your model of dish as sky have changed their dishes a few times in recent years and you may find that it wont fit on the end. Any chance of a pic of the dish and LNB and I will be able to tell you which 1 you will need. :)
 
I thought I could use somethign like a multiswitch http://www.satelliteinstaller.com/satellite_multiswitch.htm


The situation that will arise in the coming months is I need to take the current system of dual LNB and 2 sat receivers (living room and bedroom) and extend this to potentially 6 receivers in total, maybe another couple if a freesat+ box gets installed.

I thought I could get a multiswitch and do this without having to get an OCTO lnb. No?
 
whitecrook said:
I thought I could use somethign like a multiswitch http://www.satelliteinstaller.com/satellite_multiswitch.htm


The situation that will arise in the coming months is I need to take the current system of dual LNB and 2 sat receivers (living room and bedroom) and extend this to potentially 6 receivers in total, maybe another couple if a freesat+ box gets installed.

I thought I could get a multiswitch and do this without having to get an OCTO lnb. No?
Click to expand...

What you have linked to is an MDU (multi dwelling unit) system. The only ones that will work with sky are the ones with 4 inputs, but they will require a different LNB to make it work.

The LNB you have at the moment will be capable of taking any signal down any cable. The one you need wont do that. Let me try and explain a bit better.

If you have a quadLNB it can take VH, VL, HH and HL (vertical high, vertical low, horizontal high and horizontal low) down any of the outputs.

The LNB that you would need would still have 4 outputs but each output is designated a polarity. So for example, output 1 will only ever output HH, output 2 will only ever output HL and so on.

You will also have the issue of whether or not it will fit on to your dish as like I said there are a few types now.

Your best bet might be to get an octoLNB and if that is not enough the have another dish put up. It is by far the best way to do it. If you go down the MDU route and something goes wrong then a sky engineer will not be allowed to touch the system and you will be paying a lot to get it fixed.

If you have 2 dishes and something goes wrong the sky can fix your system. :D

Hope that has helped, I know im not the best at explaining things. :)
 
dandos23 said:
What you have linked to is an MDU (multi dwelling unit) system. The only ones that will work with sky are the ones with 4 inputs, but they will require a different LNB to make it work.

The LNB you have at the moment will be capable of taking any signal down any cable. The one you need wont do that. Let me try and explain a bit better.

If you have a quadLNB it can take VH, VL, HH and HL (vertical high, vertical low, horizontal high and horizontal low) down any of the outputs.

The LNB that you would need would still have 4 outputs but each output is designated a polarity. So for example, output 1 will only ever output HH, output 2 will only ever output HL and so on.

You will also have the issue of whether or not it will fit on to your dish as like I said there are a few types now.

Your best bet might be to get an octoLNB and if that is not enough the have another dish put up. It is by far the best way to do it. If you go down the MDU route and something goes wrong then a sky engineer will not be allowed to touch the system and you will be paying a lot to get it fixed.

If you have 2 dishes and something goes wrong the sky can fix your system. :D

Hope that has helped, I know im not the best at explaining things. :)
Click to expand...


OK i'll look into that.

But it's not Sky. It's just a basic FTA sattellite system using an 80cm 'tall oval' dish. There's a pic of the same dish in my orions belt picture in photography, in front of next doors sky dish. I understand that the LNB for the 'vertically squashed i.e wider than tall' sky dishes are different to the type my dish uses. Are you saying that you get different types of quad lnb (and I mean different output types,) not just different because it's a different shaped sky dish etc IYSWIM
 
Last edited:
You can use a multiswitch and a quattro lnb but it will be a lot more expensive then a octo. Although it will be tidy install, plus you can the mix in tv and fm signals down a single cable from. The multiswitch and install triplexer face plates giving you sat tv and fm from 1 cable.
 
You must log in or register to reply here.
Back
Top Bottom