sky tv

[jobloggs]

Probably not the right forum but----

is it possible to split the cable from one sky dish to feed 2 sky boxes?

 

[plugwash]

A LNB (the bit that sits at the focus of the dish) can be in one of four modes which are set by the receiver. This means that you cannot simply split the signal.

For up to eight sattalite tuners (a regular sky box is one tuner, a sky plus or sky HD box is two tuners) a LNB with multiple outputs can be used. (duals and quads are command, eights are less common but can be purchased if you know where to look)

For more tuners a quattro LNB (which give out the signals for all four modes on seperate cables) would be used with one or more multiswitches. Usually a larger dish is used too though i'm not sure if this is really nessacery.

Be aware that there are two common mounting schemes for LNBs. Sky dishes use a system where the LNB slots onto the arm. Most other dishes use a 40mm collar mount system. There are mounting clips to let you use a collar mount LNB on a sky dish but not vice-versa.

 

[Lectrician]

For more tuners a quattro LNB (which give out the signals for all four modes on seperate cables) would be used with one or more multiswitches. Usually a larger dish is used too though i'm not sure if this is really nessacery.

With a quattro LNB and multiswitch you should always use a larger dish for two reasons.

1. The multiswitch is not a booster, and it has inherent losses which cannot be avoided in manufacture.

2. If you have a house or site that is large enough to warrent a multiswitch installation you are likely to have longer cable runs than a standard install (a standard zone 1 sky dish has a guide of 20-30m). Longer runs will incur larger losses.

A larger dish will provide a higher signal to start with, overcoming any losses.

You cannot effectively 'boost' a satalitte signal although such 'boosters' do exist.

In the south of the country a 60cm dish is commonly used with a multiswitch, and in the north an 80cm is recommended.

Setting up a multiswitch, especially if you also distribute the UHF and possibly FM/DAB, is not a DIY task. The four inputs need balancing after first correctly aligning the dish to provide an equal signal on all four outputs (when alligning, allowing 1 or 2 outputs to reduce their signal to allow the other outputs to 'pull up').

You also need to take account of the UHF slope.

Many of the cheaper (well maybe not cheaper but poorer quality) mutliswitches do not have a great enough dB seperation between inputs to be greatly reliable. The labgear from screwfix has a very poor spec in terms of this and yet is more expensive than a decent Triax or Televes model. The same goes for the quattro LNB - If you compare a cheap one to a decent make you will see the signal strength when tested will be far lower, and the cross talk noticeable.

With larger installs you are best to use WH100 type coax for all the cable runs as opposed to the RG6 stuff often used. RG6 is fine for shorted low loss runs. Sky often use RG6 'shotgun' for sky+ installs as it is easier to fit, but they still use WF100 on single installs.