Three LNBs, one aerial question

[SC]

In our gites we have three TV's supplied from a single aerial and a mains powered signal amplifier in the attic that has separate connections and gain controls for each TV. We want to add a 3-LNB dish and three receivers to the setup, and if possible would like to use the existing cables from attic amplifier to each TV.

We have done this in our house with one TV/aerial/dish using a y-connector in the attic that I assume separates the voltage/signal to and fom the aerial and dish.

My question is, can I connect the cables from each LNB to the three existing cables that run from the attic amplifier to each TV, using the correct y-connectors?

Or will the possibility that all three existing cables from TVs to amplifier are connected at the amplifier cause this to rip, tear, and blow up?[:)]

Thanks in anticipation,

Steve

[Nick Trollope]

In a word, no.

The signal type from the LNB and the aerial are different, so the TV aerial amp will not work (and for a variety of other reasons). The chances are, if the coax is of decent quality, it will work.

Your best solution is to use a dual-output (H+V) universal LNB and an LNB switch in place of the aerial amp. You can still plug the TV aerial into the switch and the TV signals will be distributed, along with the satellite IF (that wot comes from the LNB). Use a 2-way (satellite/TV) outlet plate at each TV and connect the TV outlet to the aerial input on the TV and the sat output to the LNB input on your satellite receiver.

Just to make things clear, you shouldn't "T" or "Y" anything into a satellite feed, except using pukka gear. And you can't do it 3 times, as the 3 receivers will conflict with each other.

Let me know if you want a drawing!

[Gyn_Paul]

Assuming the mast head amp received its volts directly and not fed up the coax then surely Nick, if its signals from 3 separate LNB's we are talking about, and they are each added to the individual RF signal downstream of the amp/splitter outputs using proper SAT+RF spliter/combiners, the DC would be filtered and not conflict ?

Having said that, if it were me and I had access to the cable runs I would have separate coax cables for RF and Sat feeds. Better quality and no attenuation, for comparatively little cost.

p

[SC]

Nick,

"Use a 2-way (satellite/TV) outlet plate at each TV and connect the TV outlet to the aerial input on the TV and the sat output to the LNB input on your satellite receiver."

I did put these in place when I renovated, but the type I bought (Legrand) are made to have only have one coax feeding them. With reference to the rest of your comment, would all receivers be independantly controllable at once?

Paul,

"Having said that, if it were me and I had access to the cable runs I would have separate coax cables for RF and Sat feeds. Better quality and no attenuation, for comparatively little cost."

Yes, I think I would, although the single cable from the attic works well in our house. Trouble is it'll have to be surface wiring and it goes against the grain if it's not absolutely necessary......

Thanks chaps, any other comments would be welcome.

Steve

[Nick Trollope]

[quote user="Sc"]

Nick,

"Use a 2-way (satellite/TV) outlet plate at each TV and connect the TV outlet to the aerial input on the TV and the sat output to the LNB input on your satellite receiver."

I did put these in place when I renovated, but the type I bought (Legrand) are made to have only have one coax feeding them. With reference to the rest of your comment, would all receivers be independantly controllable at once?

[/quote]

Yes these are "diplexer" plates (or more likely, triplexer plates with an output for FM radio, too). They are fed with a single feed (which comes from the sat switch) and filter the signal to the appropriate outlet (which are all on different frequencies - 88-108Mhz for radio, 470-860Mhz for TV & 1.2Ghz for satellite).

At any particular output frequency (a channel, perhaps), an LNB can produce a "horizontal" or "vertical" output. This refers to the polarity (H or V) in which the radio signals travel from the satellite. This effectively gives to outputs (or channels) for a single frequency. The satellite receiver selects the H or V signal by sending a DC voltage back up the coax to the LNB. This is why you cannot connect 2 receivers directly to an LNB - they are bound to conflict at some time, causing damage to the LNB & the receivers, quite possibly. A satellite switch (using a dual output LNB) has both the H & V signals "in" it, and takes over the selection from the LNB.

I have a Philips 16-way switch (superb, but then I know the designer), which accepts inputs from an LNB, TV aerial, FM aerial DAB aerial & an "auxilliary" input. I feed this into (approx!) 7 sky boxes (I also feed the second output of one of the Sky boxes back into the aux input to allow distribution of 1 subscription channel to all the other TV's).

If your existing cable is of good quality, you do not need to replace, or double it.

Yes, I guess Paul is right, you could combine "downstream" of the TV amp, but you would need 3 LNB's, see above. I can't see the point really, when a good dual out LNB & switch can be obtained for less then 250€ (probably).

[Eslier]

OK, just to complicate matters even more than they already seem to have become, I'm going to suggest another option.

First however, I'm not sure why there is all this talk of three LNBs. For what you want to do, all you need is a single "quad lnb" which is a single unit, requiring only one dish but with four outputs. You will then need three seperate cables from the LNB into your attic.

Then comes the clever bit . . .

Why not put the three Sky digiboxes in the attic.  Into each box, take one of the new cables from the  LNB. Also into each box, take one of the feeds from the aerial signal  amplifier into the "RF  In" connection.  Then  connect the existing RF cables that go down into each gite  to one of the RF out  conenctors in each digibox. It needs to be the one that has an optional switchable voltage which off the top of my hear is RF2. You then need to tune one of the RF channels on each TV to the output signal from the digibox.

Then, or better still before you start this, buy yourself three "TV Link" little thingies (pretty cheap, around £7.50 each I think) and plug this into the back of the TV aerial socket in each gite. You should then find that your Sky remote will control the remote digibox from the gite without any problem and you'll still get normal TV. You get what you want and have the added bonus that the guests can't fiddle with the digibox other than by the remote, and you don't have to install any new cables to the gites.   The only thing is that you'll need to replace any of those fancy three way aerial sockets with a standard single socket as the filters in the three way ones don't allow the control voltage through needed for the TV Link jobbie.

[SC]

"First however, I'm not sure why there is all this talk of three LNBs. For what you want to do, all you need is a single "quad lnb" which is a single unit, requiring only one dish but with four outputs."

Thank you for that, shows how much I know about what's available!

It's just that I read this thing in LF where this gite owner listed UK television as a must have for good quality lettings [:D] so I thought we'd add FTA.

Steve 

[Eslier]

I see from your website, Steve, that you are in Brittany so don't be talked into believing you need one of those ugly great 80cm dishes sold in France. A standard 40cm minidish as used in the UK will do the job fine and look much better on your attravtive old buildings.  You can buy a dish, quad LNB, spare remote and the TV Link jobbies from www.satcure.co.uk  I've had a few things from them and they are great to deal with and don't mind posting to France. For Sky digiboxes then ebay uk is probably your best bet but make sure you only buy ones with a remote and that are confirmed as in working order. I have a personal preference for Panasonic digiboxes (I've got five systems) but, because of their excellent reputation, often go for a little bit more than some other makes on ebay.   Satcure will also be able to sell you a sat finder meter with switchable hi/lo band readings which I recomend you get as it will make setting up the dish acurately much easier. Using a meter is also the only way to optimise the fine adjustment which can make the difference between getting a good signal in bad weather or not.

Yes, I agree that providing English TV in gites aimed at the more lucretive UK market is imortant. It does seem to be one of those must have luxuries and with the football world cup this summer I suppose it is even more essential.