Anyone ever used a stacker-destacker?

**Chris** · 13-11-2008, 15:20

I'm planning to buy a Humax Freesat+ box (after Christmas, when they're cheaper!). However I'm reluctant to have any additional drilling done to get a second cable down from our dish. Drilling through the external walls of a wooden house can give rise to all sorts of problems so it's best avoided where possible.

I have come across this stacker-destacker system:

http://www.cyberselect.co.uk/range/1293

I understand the technology is regularly used to pipe Sky around flats, but this is a domestic version simply intended to eliminate the need for a dual cable when a dish is used with a PVR, especially when an existing single-cable system is being upgraded, as is the case with me.

I'm wondering whether anyone has ever used a system like this? The specs are very demanding in terms of min/max cable length, cable quality, lack of sharp kinks in the cable and so on. I don't want to spend a load of dosh on this sort of kit and then find out it won't work with my existing cabling.

danielf · 13-11-2008, 15:49

Why do you need a second cable? Can't you use the existing one?

**Chris** · 13-11-2008, 16:06

The Freesat+ box is a PVR (watch one, record one; or record/pause/rewind one, record one; or record two), much like Sky+ or V+. It requires a dual LNB at the dish and two cables from the dual LNB to the box, to feed its two tuners.

danielf · 13-11-2008, 16:10

Quote:

Originally Posted by Chris

The Freesat+ box is a PVR (watch one, record one; or watch/record/pause/rewind one, record one; or record two), much like Sky+ or V+. It requires a dual LNB at the dish and two cables from the dual LNB to the box, to feed its two tuners.

Ah, why does it require two separate inputs? My Humax Freeview PVR box only requires one input which comes off a simple splitter to make use of the tuner built in the TV as well as the two in the PVR.

**Kymmy** · 13-11-2008, 16:13

Freesat means that you;re using an LNB which freeview does NOT need... As a single LNB can be only either horizontal or vertical polarized at any one time means that a twin LNB is needed for twin tuners (that way one tuner can be H whilst the other can be V polarized

**Chris** · 13-11-2008, 16:20

Quote:

Originally Posted by danielf

Ah, why does it require two separate inputs? My Humax Freeview PVR box only requires one input which comes off a simple splitter to make use of the tuner built in the TV as well as the two in the PVR.

With terrestrial TV, there is only a one-way signal flow from the aerial to the tuner, so with a splitter, and perhaps an amp, you can run as many tuners as you like off a single aerial.

With satellite TV, there is a two-way signal flow: from the LNB to the tuner carrying the broadcast signal, and from the tuner to the LNB telling it how to polarize itself to receive the channel the tuner requires.

Thus, with a satellite installation, you have to have one LNB, and one cable, for every tuner you want to run.

Except that you can buy 'dual' or 'quad' or even 'octo' LNBs that pack multiple LNBs into a single unit, with two, four or eight cable outputs as appropriate; and you can optionally add a stacker-destacker unit, which allows two tuners to control two LNBs via a single cable, by shifting the frequency used by one of the LNBs down as it leaves the LNB, and back up again as it arrives at the tuner (effectively, stacking two signals into one cable at the rooftop, and destacking them behind the TV).

Having read up on this on a couple of sites, I'm familiar with the operating principles, but also the limitations (they appear to be quite choosy about the quality of installation they will work with) - hence this thread, to solicit opinion from people who have tried them out.

altis · 13-11-2008, 16:26

Kymmy, you forgot high and low band too!

H/V polarization is switched by changing the voltage on the cable.
H/L band is switched by the presence or absence of a tone on the cable.

This is why you can't normally share LNBs on one cable.

However, what you can do is shift the output of one of the LNBs up the spectrum so that the receiver can see both outputs simultaneously. Trouble is that doubles the bandwidth you need down the cable - hence all the restrictions that Chris mentioned.

You'd have a better chance of this working if you have a descent drop cable - but I suspect it isn't! I've no experience of these but know they're rare - probably for a reason. You might find someone more knowledgeable over here. They're a helpful lot too!

http://www.satellites.co.uk/

-----

Alternatively, try squeezing the other cable in through a door or window with one of these:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180305080397

danielf · 13-11-2008, 16:26

Quote:

Originally Posted by Chris

With terrestrial TV, there is only a one-way signal flow from the aerial to the tuner, so with a splitter, and perhaps an amp, you can run as many tuners as you like off a single aerial.

With satellite TV, there is a two-way signal flow: from the LNB to the tuner carrying the broadcast signal, and from the tuner to the LNB telling it how to polarize itself to receive the channel the tuner requires.

Thus, with a satellite installation, you have to have one LNB, and one cable, for every tuner you want to run.

Except that you can buy 'dual' or 'quad' or even 'octo' LNBs that pack multiple LNBs into a single unit, with two, four or eight cable outputs as appropriate; and you can optionally add a stacker-destacker unit, which allows two tuners to control two LNBs via a single cable, by shifting the frequency used by one of the LNBs down as it leaves the LNB, and back up again as it arrives at the tuner (effectively, stacking two signals into one cable at the rooftop, and destacking them behind the TV).

Having read up on this on a couple of sites, I'm familiar with the operating principles, but also the limitations (they appear to be quite choosy about the quality of installation they will work with) - hence this thread, to solicit opinion from people who have tried them out.

Cheers, that explains it.

I will be watching this thread then. If I ever go freesat, I might want to consider this option, if only for esthetic reasons.

**Chris** · 13-11-2008, 16:32

Quote:

Originally Posted by altis

You'd have a better chance of this working if you have a descent drop cable - but I suspect it isn't! I've no experience of these but know they're rare - probably for a reason. You might find someone more knowledgable over here. They're a helpful lot too!

http://www.satellites.co.uk/

Hmmm ... mixed reviews over there to say the least.

Matth · 13-11-2008, 17:37

http://www.satcure.com/reviews/review91.htm - Satcure used to sell a stacker/destacker, but as their review says, they discontinued it because it didn't work very well.

You are asking the cable to handle double the frequency, and it's losses will be more than double per unit length, so add up enormously unless the run is short.

Another alternative to the flat window cable, might be threading a short length of ultra-thin co-ax through a vent, but finding suitable connectors to make a water-resistant link from standard sat cable to bootlace cable would be difficult.

With higher losses per unit length, it would be impractical to make an entire run in thinner cable.

altis · 13-11-2008, 17:57

If you're desperate to go the stacker route then you could just put them either side of the bit that goes through the wall. That way you'd get the minimum loss on the length that matters. It sounds like you may be able to pick up one cheap

...or drill a window frame.

iain_herts · 13-11-2008, 17:58

if your tv A/E cable runs near the dish then you can get what we call a UHF/SAT combiner it will use the A/E cable to send both signals then all u need is a outlet socket

or

cut the cable that come through the window pull it out and put a small lenth of the sky shot gun cable though it and join on that way.