LNB question

coL

We recently moved in to a house that had an old Sky satellite dish fitted.

Looking at the LNB on the dish it has two outputs, is it safe to assume that this LNB is a dual/twin given it has two outputs? (is there a difference between a dual and twin LNB other than terminology and a way to check which it is?)


Working on the assumption that it is a dual LNB I was planning to feed two separate receivers from it. I ran a cable to each receiver and when I turned on the first receiver I got all the usual channels but then when I turned on the second receiver at the same time I could only get some of the channels on it. When I powered off the first receiver I couldn't get any channels on the second receiver.

Any ideas or suggestions what the problem might be?

Am I correct in my understanding that if it's a dual LNB then I should be able to run two receivers from it separately and independently of one another or is it a case that one receiver controls the LNB and provides the power?

Alternatively could it be the LNB that's the problem?

Barnaboy

coL wrote: »

We recently moved in to a house that had an old Sky satellite dish fitted.

Looking at the LNB on the dish it has two outputs, is it safe to assume that this LNB is a dual/twin given it has two outputs? (is there a difference between a dual and twin LNB other than terminology and a way to check which it is?)


Working on the assumption that it is a dual LNB I was planning to feed two separate receivers from it. I ran a cable to each receiver and when I turned on the first receiver I got all the usual channels but then when I turned on the second receiver at the same time I could only get some of the channels on it. When I powered off the first receiver I couldn't get any channels on the second receiver.

Any ideas or suggestions what the problem might be?

Am I correct in my understanding that if it's a dual LNB then I should be able to run two receivers from it separately and independently of one another or is it a case that one receiver controls the LNB and provides the power?

Alternatively could it be the LNB that's the problem?

Could very well be the LNB. Very cheap to replace and easy to install.

The Cush

coL wrote: »

Looking at the LNB on the dish it has two outputs, is it safe to assume that this LNB is a dual/twin given it has two outputs? (is there a difference between a dual and twin LNB other than terminology and a way to check which it is?)

Back in the day, early 90s, a twin output LNB had 2 independent outputs and a dual LNB had separate H & V outputs, dual LNBs disappeared once sat broadcasting expanded into the Hi-band and were replaced by quattro LNBs. Nowadays the terms twin/dual are used interchangeably for any twin output LNB.

I too would think the LNB is at fault, quad (4) output LNBs are now probably the most common and cheap and will give you spare outputs for possible use for other rooms or if an other output develops a fault.

The Cush

coL wrote: »

We recently moved in to a house that had an old Sky satellite dish fitted.

If the dish is a pre 2009 Mk.4 Sky dish the LNB mount is different and might be an idea to replace the dish, otherwise a legacy adapter will have to be used to fit the newer LNB on the old dish

http://www.satcure.co.uk/tech/LNBpics.htm

https://www.freetv.ie/sky-mk4-to-mk3-lnb-legacy-adaptor/
https://www.freetv.ie/satellite/dishes/lnbs/

Wheety

As far as I know the LNB needs to receive power from the receiver. This is probably the first box in your scenario. 2nd box only receiving some channels would indicate a problem.

If you want recording ability might as well get a quad LNB and run 2 cables to each box.

coL

Thanks for the replies.

I suspect that the LNB is the problem but wanted to be a bit more certain before I change it. Is there any way to test if an LNB is working properly on both outputs?

Was hoping to make do for a while with what is in place rather than starting to install new stuff, is there any way to know by looking at it whether or not it is a pre Mk4 dish? I can put up a picture if needed.

It does seem like there is a problem with the power to the LNB alright. Am I correct in thinking that the LNB should be getter power from both receivers so that it can work when one is turned off or is it a constant feed from one of the receivers?

This might be a silly question but does it matter which input on the receiver I plug the cable into? I have connected the cable to the nr 1 input on both receivers, should I connect the cable on one receiver to the nr 2 input? Would it make any different if I did?

Going for a quad LNB would be the ideal solution, but we live in a dormer bungalow in which the dormer section was done a good few years after the downstairs. As a result there is only a single cable that runs to the main tv point in the living room from the upstairs crawl space. It is not a straight run and I am not sure how easy it would be to pull a second cable as it definitely goes around a few bends and seems very tight. Currently the tv and a single satellite feed are joined to a splitter to run through this cable. Its an adequate solution but makes things work but means I cant record and watch different programmes (not a massive issue). I assume there is no way to combine two satellite feeds into the single existing cable?

Wheety

Not cheap but

https://www.freetv.ie/global-stacker-destacker/

coL

Wheety wrote: »

Not cheap but

https://www.freetv.ie/global-stacker-destacker/

Thanks for that. At least I know something is available as a solution if it comes to it. Can get two cables to the other receiver easily enough so it might not be necessary.

Gerry Wicklow

It's possible it might be a bad connection on the second cable either at the box or LNB meaning the LNB isn't getting (sufficient) power.
Another option, if it is too difficult to run a 2nd cable to the main location but is feasible at the other would be to use the 2nd box for recording and access the recordings over your network. With enigma based boxes, it is fairly simple to configure them to access each others HDDs or a central NAS.

The Cush

coL wrote: »

I suspect that the LNB is the problem but wanted to be a bit more certain before I change it. Is there any way to test if an LNB is working properly on both outputs?

Connect a known good receiver on each output would be the simplest.

Of course the problem could also be with the connections at each end and/or a damaged cable, water ingress etc. Physically check the connections at both ends of the cable, ensure they are intact and secure. Regarding the cable it may not show any external physical damage.

coL wrote: »

Was hoping to make do for a while with what is in place rather than starting to install new stuff, is there any way to know by looking at it whether or not it is a pre Mk4 dish? I can put up a picture if needed.

Have a look at the LNB mount of the dish, the Mk.4 has a spirit level just under the LNB feedhorn, the earlier dishes don't. The Mk.4 sits on the dish arm, the earlier ones slide into the dish arm. I suspect it's an earlier dish as it has a twin output LNB, the newer dishes came with a quad LNB I believe.

Mk. 4 dish

Mk.1-3 dish

coL wrote: »

It does seem like there is a problem with the power to the LNB alright. Am I correct in thinking that the LNB should be getter power from both receivers so that it can work when one is turned off or is it a constant feed from one of the receivers?

Power comes from all connected receivers.

coL wrote: »

This might be a silly question but does it matter which input on the receiver I plug the cable into? I have connected the cable to the nr 1 input on both receivers, should I connect the cable on one receiver to the nr 2 input? Would it make any different if I did?

Makes no difference.

coL wrote: »

I assume there is no way to combine two satellite feeds into the single existing cable?

Regarding the stacker/destacker, it works by shifting one satellite downlink frequency higher up the band, the problem here is the cable quality. Can the cable handle the higher frequency required by the stacker?

http://www.satcure.co.uk/accs/stacker2.htm

NewClareman

coL wrote: »

Going for a quad LNB would be the ideal solution, but we live in a dormer bungalow in which the dormer section was done a good few years after the downstairs. As a result there is only a single cable that runs to the main tv point in the living room from the upstairs crawl space. It is not a straight run and I am not sure how easy it would be to pull a second cable as it definitely goes around a few bends and seems very tight. Currently the tv and a single satellite feed are joined to a splitter to run through this cable. Its an adequate solution but makes things work but means I cant record and watch different programmes (not a massive issue). I assume there is no way to combine two satellite feeds into the single existing cable?

You have a number of options to feed two satellite signals down a single coax. The stacker/destacker has the advantage that it should work with any combination of receiver and set top box. However, it is very fussy with regard to the quality of the coax, and the length of cable run.

The modern means of supporting multiple signals is to use a Unicable LNB, this is supported by Samsung TV’s since the D Series in 2011. Many other Tv’s, but not all, support it also. Most modern satellite and combo receivers, other than Sky, also support it. (Sky use their own proprietary version that is not compatible with the Unicable Standard.)

My preference would be to use a Unicable 2 LNB, which can be configured for Unicable 1 to support older equipment and your existing terrestrial feed. If some of your older equipment is not Unicable compatible you can get a Unicable 1 LNB, with additional legacy outputs for older equipment.

If you have Sky equipment, or might be getting it the future, a better option is to use a quad or Quatro LNB feeding into a Multiswitch. This would give you legacy outputs for older equipment and Unicable for others. Some also support Sky versions of SCR/Unicable, giving a very flexible, futureproof option.

coL

Thanks everyone for all the helpful advice and suggestions.

It's possible it might be a bad connection on the second cable either at the box or LNB meaning the LNB isn't getting (sufficient) power.
Another option, if it is too difficult to run a 2nd cable to the main location but is feasible at the other would be to use the 2nd box for recording and access the recordings over your network. With enigma based boxes, it is fairly simple to configure them to access each others HDDs or a central NAS.

I think at this point I have established it is a problem with the LNB. Last night I switched over the feeds (and also redid the connector on the feed that was giving the problem just to be sure) and now the second receiver is working perfectly while the first receiver doesn't tune in any of the channels.

Connect a known good receiver on each output would be the simplest.

Of course the problem could also be with the connections at each end and/or a damaged cable, water ingress etc. Physically check the connections at both ends of the cable, ensure they are intact and secure. Regarding the cable it may not show any external physical damage.

I haven't checked the connections at the LNB itself yet. I presume swapping the two connections on the LNB itself and see what effect that has on the receiver will tell me whether or not its the LNB or the cable from the LNB to the point where I swapped the feeds over?

Power comes from all connected receivers.

Very helpful to know and one of the main things I was uncertain of.

Regarding the stacker/destacker, it works by shifting one satellite downlink frequency higher up the band, the problem here is the cable quality. Can the cable handle the higher frequency required by the stacker?

The cable running down to the main tv point is fairly thick if I remember correctly but I will definitely double check if I do decide to go with the stacker option.

The modern means of supporting multiple signals is to use a Unicable LNB, this is supported by Samsung TV’s since the D Series in 2011. Many other Tv’s, but not all, support it also. Most modern satellite and combo receivers, other than Sky, also support it. (Sky use their own proprietary version that is not compatible with the Unicable Standard.)

My preference would be to use a Unicable 2 LNB, which can be configured for Unicable 1 to support older equipment and your existing terrestrial feed. If some of your older equipment is not Unicable compatible you can get a Unicable 1 LNB, with additional legacy outputs for older equipment.

If you have Sky equipment, or might be getting it the future, a better option is to use a quad or Quatro LNB feeding into a Multiswitch. This would give you legacy outputs for older equipment and Unicable for others. Some also support Sky versions of SCR/Unicable, giving a very flexible, futureproof option.

My current set up is a Sony Bravia smart TV (1.5 years old) in the living room and an old Sky+ box I inherited in the kitchen. I don't have an active Sky package but get the FTA satellite channels on the one in the kitchen so its handy as a second tv. Not going to change the living room tv arrangement anytime soon but might upgrade the kitchen arrangement in the near future. Not sure if the Sony TV is unicable compatible but will look into it. Getting a Unicable LNB with a legacy port does seem like a very smart option. Can Unicable run in a standard RG6 (or RG59 at a push) cable or does it need something different?

Just out of curiosity how do multi-switches actually work?

The Cush

coL wrote: »

Just out of curiosity how do multi-switches actually work?

They work like an LNB except with more outputs and the option to combine a terrestrial aerial feed down each sat cable. They require 4 feeds from a quad or quattro LNB on the dish.

coL wrote: »

The cable running down to the main tv point is fairly thick if I remember correctly but I will definitely double check if I do decide to go with the stacker option.

Thicker cable could be CT125 or similar, I've used it in the past, check for markings on the cable.
The only way to know for sure will be to test it with a stacker.

coL wrote: »

Can Unicable run in a standard RG6 (or RG59 at a push) cable or does it need something different?

It uses the same intermediate frequency (I.F.) range as any LNB so no problem.

coL

So over the weekend I got the ladder out and went up to the dish to look at the connection on the LNB itself.

The first thing I noticed is that it is actually a Mk4 dish that has a quad LNB (the weather cover was pulled down and there were only two outputs connected which is why I thought it was only a dual).

I tried a few combinations of connecting one or both cables to the different outputs without much luck. I did manage to confirm that at least two of the outputs are working but I didn't have enough time to see if they all were. When I tried the connection that was previously not working in the good output I couldn't get a signal. I put a new connector at the end of this cable but it didn't make any difference so now I am a bit puzzled as to what the problem might be, could it still be the LNB?

All I did was switch the connections but the reception on the receiver that was previously good has now deteriorated. The dish and LNB are secure and didn't move, I assume a little bit of movement like loosening and tightening a connection shouldn't make the reception go bad like that should it?

Is it still likely that its the LNB and that the movement just made it worse? Is there any chance that the old sky box might be stopping me from tuning in two receivers?

The Cush

coL wrote: »

I tried a few combinations of connecting one or both cables to the different outputs without much luck. I did manage to confirm that at least two of the outputs are working but I didn't have enough time to see if they all were. When I tried the connection that was previously not working in the good output I couldn't get a signal. I put a new connector at the end of this cable but it didn't make any difference so now I am a bit puzzled as to what the problem might be, could it still be the LNB?

Could be the cable.

Test the "good cable" on all 4 outputs with a working box. Do they work?
Test the "bad cable" on all 4 outputs with a working box. Do they work?

coL

I didn't get a chance yet to test the good cable on all outputs yet but what I did do is disconnect the feed to the second box (the old Sky+ one) and the reception on the other built in tuner went back to being perfect again.


Is there any reason why just connecting the second box would have an effect on the signal quality of the other? Can I take this as confirmation of a bad LNB?


Also is there any chance that the fact it is an old sky+ box with a subscription is having an effect?


The way I understood it is that with a quad LNB all four receivers operate separately and have no interaction with one another so it doesn't matter what is connected to each. Is this right?