I have just been rewiring our house and have put a long length of CT100 cable (the stuff from B&Q) down from the loft to under the stairs, plus further bits from under the stairs to where ever we might want the TV (and the same for phone and network cabling) and was planning to join the sections with coax plugs as required.
I was talking to a satellite system installer last week and he said you could not have any joins in cable from a satellite dish. I really don't want to hack off the new plaster to put in a single cable all the way down. Is he right, or can it be joined?
In an ideal world there'd be no joints as joints lead to signal loss.
However in practice you can join the cable. Personally, I'd recommend fitting 'F-Plugs' to the ends of the cable to be joined. Generally these just 'screw' onto the end of a prepared cable. However, crimp versions are available which need a special tool.
Then use a female-to-female threaded "F" barrel to joint the two together.
If there is an chance whatsoever of the juction getting damp wrap it in 'Self-amalgamating' tape (Not insulation tape!)
It's quite possible all the bits are availble from B&Q or screwfix. The bits to look out for are shown here:
- If you are thinking of adding lengths of cable on, this can be done as long as you use proper 'F' connectors and barrels to do so and make a decent job. Although introducing a connector, causes some effect on the signal, if this is for the Astra constellation (carries Sky) in the UK, then it should be fine as long as only one or two connectors are used.
- If you are thinking that you can do something like a TV distribution arrangement with a signal booster, no you can't do that in the same way as you would for a TV. This is because the receiving element at the dish - known as the Low Noise Block (LNB) is an active device with electronics. The satellite transponders deliver signals in horizontal and vertical polarisations and in two bands - 4 combinations in all. Depending on which channel you are watching and hence which transponder, the LNB has to be switched by the receiver to select it. This means a one-to-one relationship between receiver and a conventional LNB having a single cable.
There are three ways around this.
1) Keep the one to one LNB to receiver relationship and have one receiver. Distribute the signal out at UHF from that receiver, along with terrestrial TV to other points in the house. This means one receiver and one satellite program watched at a time. You could site the receiver under the stairs because there are solutions to handle the issue of using the remote - basically a sensor near the TV which picks up the infra red and passes the electrical signal back along the UHF coax.
2) You can fit a quad LNB to the dish. This is basically 4 separate LNBs in one case and has up to 4 cables coming from the dish
- each to a separate receiver. Each then runs independently.
3) You can fit a quattro LNB to the dish and run four cables to a multiswitch (a special kind of head end) fitted (e.g.) under the stairs. A quattro LNB provides all four signal combinations to the multiswitch. The receivers, and you could have a lot of outlets if you want, signal to the multiswitch as though it is a single LNB and the multiswitch then provides the appropriate signal. This technique is also used in multi-occupancy dwellings to avoid needing to have lots of dishes on the roof.
He is wrong. I wonder how he thinks that people manage to have wallplates with a satellite outlet, or even how the lead is connected to the digibox if you're not allowed connectors! If the signal was so weak that one more connector would kill it, there would loads of people unable to receive anything.
Does the dish have to be outdoors, or can it go in the loft (it's an old loft, no foil insulation here!) - perhaps with a larger dish? If outdoors, can I hide it down the garden on a long lead or is there too much signal loss with (say) 50m cable from dish to receiver?
Yes, it can be. BUT there will always be a little loss and a little reflection. Basicall older teh niners tofether, and wrap it with isnutailin, then pull teh outher sheaths back over and connect them by careful sodering.
Or get a connector and fit that, tape it and bury it.
Satellite frequencies are severley attentuated by almost everything. Maybe you could get away with fibreglass or persex radome in front of it, but nothing that absorbs/contains water like tiles or slates or timber and nothing metallic either.
Remote dishes in general need power run to them for a mast head amplifeir of some sort to boost the signals before the long cables reduce them all over again.
When the original SKY installer came to do mine he couldn't even be bothered to measure the complete run of cable (straight run) and instead joined 2 cables with f-types. That's how much they are concerned about it.
For Sky there will no noticeable difference. If you want to pick up weak satellite stations then it may make a difference.
What you need to consider more is the length of the cable run and to make sure that any joins are water sealed with self amalgamating tape or similar.
On Mon, 26 Apr 2004 10:27:39 +0100, in uk.d-i-y "Roger Moss" strung together this:
If you use a Global Loftbox it takes care of all the joining of cables as the sat feed is run through the distribution amp first and also redistributes the sat feed to other tv's throughout the house. I've fitted a few and had good reports and also use one at home. Or you could just join it as others have said
It's the cable directly from the dish. This can't go through a distribuition amp, without being decoded by the box first, as the signals from the satellite are not normal TV ones.
On Mon, 26 Apr 2004 20:43:41 GMT, in uk.d-i-y Ian Stirling strung together this:
Try reading up on the product I mentioned in the post. I won't point out the several incorrect comments in your post just yet, nah f*ck it, I will. I know it's the cable directly from the dish, no need to point that out again. The satellite signal can go through a distribution amp, just not a normal uhf\vhf amp. It's a signal in a frequency range, it can be amplified by a suitably matched amp. It doesn't need decoding before being amplified. I know satellite signals are different from normal tv ones, If I got it wrong how do you suppose it all worked when it was installed and tested? Bearing in mind I have fitted these units, you obviously haven't.
I've got a question on the Loftbox Lurch, I've one installed and working fine with 'normal' TV and Sky at my sister's and another sat here on the floor next to me waiting to be fitted here. Just what the heck are Gold Mine points and what can I do with 10 of them???
I've looked at this one, Lurch, and from the diagram it appears to work as follows:
- TV, VHF and satellite dish cables are brought together at the Loftbox and combined though a filter. THere may or may not be amplification. VHF signals are those below 300MHz, then UHF terrestrial TV goes from approx 400 to approx 850MHz. The satellite IF signal between the LNB and the receiver ranges from about
950 to 1950 MHz. The main point here is that it is a cabling convenience of everything from the box to the prime TV position on one cable.
- A single cable goes from the Loftbox to a filter box (typically in the living room) which then splits the signals back out again into TV, VHF and satellite.
- The TV and satellite signals go to the (typically Sky) satellite receiver.
- One UHF output from the satellite box goes to the living room TV, the other optionally back to the Loftbox on a separate cable.
- VHF and UHF distribution amplification in the Loftbox then provides for outlets to go to a number of TV sets (4?) in other parts of the house.
- If all of this is connected up, it should be possible to watch terrestrial TV and the satellite channel selected on the satellite box. With TVLink sensors, the satellite box could also be controlled from the other rooms with TV.
However........
What I am pretty sure that it won't do is to deliver a satellite signal to more than one receiver in one place.
This requires either a quad LNB or a quattro LNB with multiswitch. Both of those require four cables (actually up to 4 with a quad) from the LNB. .andy
On Mon, 26 Apr 2004 23:31:54 +0100, in uk.d-i-y Andy Hall strung together this:
Sounds about right.
Or two, if you use the return feed as well.
Yep, you can get 8 way as well, and they also do a cascadable amp to add more if required.
Yep.
No more than a single LNB would under any 'normal' circumstances.
Yep, but then you'd need to bypass the loftbox therefore rendering it as just a UHF distribution amp. Unless you combine the four signals from the quad before the loftbox and back out again somewhere, although by the time you've finished you might want to just design a system from scratch without the loft box but use your own splitters\filters etc.
Right. The point that I was trying to get to so that people would not be confused is that a simple distribution amp can't take a single LNB signal and deliver it to N positions for simultaneous use of receivers. The Loftbox picture almost gives that impression, but obviously it's not technically possible.
This is basically what I did.
I wanted to have a fairly large number of outlets around the house for TVs and VHF radio simply so that rooms can be rearranged without long trailing leads. The shape of the house lends itself much more to having a tree shaped cabling arrangement, so I created a headend for UHF and VHF distribution in the loft. Cabling is run from there to passive splitters at various locations and then sockets are cabled to these. This head end has signal equalising filters etc. to give equal results on all channels from two transmitters. There will be between 20 and 30 outlets when it's finished.
I then wanted satellite distribution to a smaller number of outlets where satellite receivers may be located. These have to be home run cabled to a multiswitch in the loft.
For this, I have used a Spaun cascadeable multiswitch to provide for inputs from two quattro satellite LNBs (one Astra, one Hotbird) and up to 10 outlets.
formatting link
DVB satellite receiver is able to select the LNB as well as the polarisation/band through signals up the cable.
This switch can also take an input from the UHF/VHF headend, so I can use a triplexing filter at the outlet, rather like the Loftbox does and avoid a separate cable from the trunked system.
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