Suggested wiring layout is given, below. We recommend that you copy this as closely as possible.
Before you begin, please make a sketch of your own proposed layout on A4 size paper. This will make it easier to see if you make a mistake. It will also allow you to send a GIF image of your sketch to our Technical department if you require help. Please note that our technical help will necessarily be limited and will be based totally on your ability to describe your layout and your problem. We do recommend that you read our eBook very carefully and, again, to employ a professional if you run into difficulties that we can not solve for you by email.
What use is a Loft Box?
A loft box is able to combine the SAT LNB, TV AERIAL and RADIO AERIAL signals and send them down a single coaxial cable to your main room. (You will also need a Return Feed back to the loft box). This reduces the cable requirement to two instead of four. It can also handle signals from a Remote Control Extender (e.g.. tvLINK) in the reverse direction.
It is important to understand the limitations of a Loft Box:
It handles modulated RF signals, not raw video. Modulated RF signals will give "average" picture quality which will usually be fine on a 14" portable TV and acceptable on a 21" TV. Analogue transmissions using NICAM will give stereo audio on a suitable TV set. Other signals (e.g.. Sky Digibox RF Out) will give mono audio. (The only way to get stereo is via Scart or Phono connections and a Loft Box can't handle those).
The more signals you try to feed in to the Loft Box, the worse the picture quality is likely to be. This is due to the limited number of UHF channels available (21 - 69) and the very real risk of cross-modulation between channels (as explained in "Piping TV Around the House".)
You *can* use your existing TV aerial cable as the return feed and simply add the new down feed using double-shielded cable. However, for best results (maximum signal with minimum interference) we recommend you use double-shielded cable for ALL connections.
The satellite TV picture quality through a Loft Box should not be significantly worse than it is when it comes direct from the Digibox RF Output, provided that you've followed the eBook advice. Obviously it can never be as good as Scart or S-V ideo quality.
To ensure best possible picture and audio, use Scart or S-V ideo (if you have a SKY-Plus model) for the larger screens. But also bear in mind that digital satellite pictures are a compromise between quality and bandwidth so they'll never be a patch on DVD quality!
The diagram shows a typical Loft Box wiring layout where the Loft Box is expected to be in the roof space or some dry upstairs location. There are optional inputs for an FM aerial, DAB aerial, security camera (or pond camera etc.) A 230 volt AC power supply is required.
The wall plate is in the main viewing room. You can choose from a selection of wall plates, below. Please use the plates and wire them as indicated in the sketch, below. The RETURN feed will allow you to distribute the Sky Digibox programme AND normal TV aerial signal to other rooms, as shown. (So it's not optional - it's essential!) A tvLINK system can be used in each room. The return feed can also carry other signals from the main viewing room (VCR, DVD etc.) These must all be tuned to separate UHF channels 21 - 69 as described in our eBook "Piping TV Around the House", which is supplied for free download with this system.
It's important that you wire up the loft box FULLY as shown in our web page wiring diagram. If you omit vital connections (such as the return feed) the unit can not work. This is obvious from the internal diagram on page 26 of our "Piping TV.." eBook.
Without the Return Feed the signals go ONLY to the living room. They can not go to TV OUT ports because there is no internal connection.
Please DO connect the Return Feed. It need only be a short link cable for the purpose of testing. Please also be sure to connect the decombiner wall plate for each output in use, otherwise you could cause damage.
To ensure correct operation of the Loft Box, please use the wiring diagram that we provide below.
The wall plates listed below the diagram are suitable for use with the Loft Box.
Use the 304115 in the main room and the PSW132, GLO27 or GLO28 in each bedroom.
We do not recommend alternative wall plates.
Frequently Asked Questions
Q. Can I use a Loft Box with a non-Sky receiver?
A. Yes but, if you want the remote extender function to work ("magic eye"), you will need to order a Global tvLINK Plus with power supply.
Q. Can you supply a single wall plate with all the features of the Triax 304115 Triplexed wall plate but without the phone connection?.
A. No, sorry. The DDU112 is designed to be used with the 304115 plate.
Q. Can I use the Triax 304114 wall plate or some other modular equivalent?
A. No, please use the 304115 as in the diagram, below. (It may be possible to use a triplexer and a diplexer module but we have not tested this.)
Q. Does the Loft Box aerial input provide power for a masthead amplifier or an MRD?
A. No. You would need to fit a suitable power supply between the Loft Box and the amplifier. Note that an aerial amplifier will overload the Loft Box input unless there is a suitable length of cable (or attenuator) fitted. The Loft Box incorporates an amplifier so, if possible, mount it as close to the aerial as possible and eliminate the masthead amplifier altogether.
Q. What is the maximum input signal?
A. Well, the maximum UHF Output level (2 Ch) = 93 dBµV
The UHF Gain from UHF Input to Downlink = 8 dB
Therefore Max UHF Input level = 93 - 8 = 85 dBµV, (2 Channels)
De-rate for number of UHF channels being received on UHF Input, (for 5 Analogue and 6 Dig Mux's we normally de-rate by 7 dB). Therefore max. UHF Input level = 85 - 7 = 78 dBµV
When analogue is switched off you can de-rate by just 4 dB so max. UHF Input level = 81 dBµV
So, dependent on what the aerial signal is (you'd have to measure it) and the gain of the masthead amplifier (if any) minus the attenuation in the aerial cable, you might have to add an attenuator at the UHF input of the Loft Box to get the signal below 78 dBµV.
The minimum signal input depends on the Freeview receivers in use. Typically they will have an input sensitivity of 26 dBµV. If you have, say, a total of 30m of cable between aerial and Freeview receiver, it will lose typically 0.15 x 30 = 4.5 dB of signal. The wall plate might lose another 2 dB making -6.5 dB lost. The Loft Box gain is 8 dB. So from the aerial (or masthead amp if used) the absolute *minimum* signal must be 26 -6.5 + 8 = 27 dBµV.
So it looks as if the system will accommodate any signal from 27 to 78dBµV. That's a heck of a wide range (bearing in mind it's a logarithmic scale) so the chances of success look quite good. However, this doesn't take into account the noise factor. The lower the signal level, the greater the effect of interference collected by, and generated within, the cable and amplifiers. Therefore it's advisable to keep the signal near to, or above, the maximum and attenuate it at the receiver if necessary.
As you can see, there's a lot of "Ifs" which depend on several variables! This is why we recommend you stick to our wiring diagram and keep the Loft Box close to the aerial. IF that gives satisfactory results, then you can test the effect of a longer feed cable. IF it's still OK, you can try moving the Loft Box (on its longer cable) away from the aerial, positioning the cable well away from any sources of interference - especially mains cables.
Q. What's the difference between the Loft Box versions?
A. The Global version has a number of accessories available for purchase. (See 2nd diagram on Global page). The Philex version is more basic.
The Triax DDU version has the added ability to accept up to FOUR LNB inputs. Two are fed down to the main room and two are fed, one to each of two bedrooms. This is a true "Multiroom" system which incorporates the features of the Global accessories in one unit (but also lets you install a Sky Digibox in two bedrooms).
Q. What do I do if I don't want to use the "Return Link"?
A. Without a Return Link there will be no outputs from the Loft Box so you must connect the "Downlink" output to the "Uplink" input on the Loft Box. You should do this anyway as an initial test to ensure the Loft Box is working.
Q. Would you recommend a masthead amplifier to be used with and powered by a Loft box?
A. No. A Loft Box normally takes the place of a masthead amplifier and is located as close to the aerial as possible. If a masthead amplifier is used, it's likely to overload the input of the Loft Box built-in amplifier unless you have a very long connecting cable or fit a suitable value attenuator to the input.
Q. Can I get best quality pictures and sound for my Flat Panel display though a Loft Box?
A. No. A Loft Box has no discernible effect on picture quality if connected correctly. However, a Loft Box passes Modulated carrier analogue RF signals such as those from the RF output of a Digibox. What you put in will be what you get out. A Loft Box won't improve it. To get the best possible quality you should use a CAT5 distribution system instead. CAT5 systems will not carry LNB signals.
All Digiboxes produce the same "RF Output" quality picture. It has nothing whatsoever to do with the choice of Loft Box (but it can obviously be affected by the choice and length of coaxial cables and the choice of UHF channels in use if they conflict with each other or with terrestrial channels. See our eBook "Piping TV Around the House").
Q. Why must I solder the TV plugs?
A. If the plugs are carrying power to a "magic eye" or to a masthead amplifier, the wire should be soldered to the centre pin. If you don't do this, it may not make a reliable connection. Even if it does, to begin with, you risk losing the connection as the copper oxidises over months or years. See instructions HERE. If you can't solder then you could fit twist-on "F" connectors and use a "090-4333 TV-F adapter". Note, however, that this arrangement produces a rather long and heavy plug, which might damage the socket in some circumstances.
Q. Why can't I use female TV plugs?
A. Female TV plugs can not be soldered so there's always a risk of a bad connection. It's better to solder a male plug to the cable then use a "COLCM - male-female adapter" to convert it. Apply silicone grease to all plug connections; this will keep moisture out and also make it easier to pull out the plug when necessary.
Q. How many plugs should I order?
A. It depends on exactly how you intend to wire up your system. As you will be making your own wiring sketch, you can mark it according to which plug you need for each connection then count the total of each type.
Q. I want to connect two or three Sky Digiboxes to a Loft Box and I want magic eyes to be able to control all of them. Please tell me how to connect everything.
A. I would stress that the Loft Boxes we sell are designed to be connected as shown in the example wiring diagrams. While small variations may be possible, it is unlikely that I can help you to design a major variation because I have no personal experience of connecting them differently and I have no knowledge of the internal workings, apart from that which is already on these web pages.
Q. I get interference on Freeview pictures but only when the LNB is connected. What's causing this?
A. We don't know the precise cause but the interference seems to come from the LNB and the simplest cure is to fit a high-pass LNB filter to each affected LNB input on the Loft Box.
Q. Is DiSEqC switching supported?
A. No, this Loft Box does not support it.
It is most important that you draw your own wiring sketch on a LARGE piece of paper before ordering! Time spent determining what you need, now, will save much hassle later!
You can order the kit at the bottom of this page.