I looked into one of these but was given the advice that if there was a chance you could run a second cable then that was your best course of action. I was told some people had joy and others not. Not wishing to take a chance I went with the second cable. Was a real pain in the you know where but well worth it. Anyway good luck...
This thread gave me the confidence to spend the money on a Stacker/Destacker, and I just wanted to report my postive experience here in case it helps anyone else.
Just over a year ago I fitted a pair of dishes (one fixed, one moving) for my first satellite experience. I thought that a pair of feeds would be enough (I bought a twin-tuner PVR), but I was far-sighted enough to run a third cable as a spare. These cables were run very neatly by taking apart my plasterboard-on-studding walls, a job I certainly did not want to repeat !
However, a year later and I'm a lot wiser. My first PVR (near the top of the Topfield range) was returned as somewhere between "disappointing" and "useless". I now realise there is no single PVR that does everything I want to do, so I now have two, therefore four feeds would be best, but of course I ran only one spare co-ax.
Happily, as I ran the cables myself I know that it's (equivalent to) CT100. Also the length that has to be "shared" is only about 6 metres. So I guessed the stacker/destacker would do the trick for me.
And it works just fine, it looks just like two cables to me. I'd like to tell you about whatever signal loss there is, but the signal strength meters on the IPBOX9000 are not really very convincing, I think the readings are faked ! But all channels seem to come in just fine (and I took the trouble to check the extremes of the frequency ranges).
On one retail website I found a warning that the Johannsen stacker must never be used with less than 7 metres of cable, but I have bought the "Global Communications" unit and it doesn't seem to mind. However, many websites warn that the Global stacker must not have a wallplate in the common cable run. The instructions with the unit are a bit less rigid, they say you must use a "stacker compatible" wall plate (but no further explanation about what a "stacker-compatible" wallplate is). I am using a wall plate of home-made construction (a double-ended F joining connector and a right-angled adaptor behind) with no problems.
The power supply draws about 9W (a bit more than I expected) so you might want to consider switching it off when not in use. In my case I also use a "Homeplug" network adapter which is responsible for 4W of load, and your average V-Box positioner has a crude power supply that drains about 7W whether you are using it or not, so all the more reason to turn them off when not in use. For timed recordings the "Standby Saver" (Google this to see what I mean) in its USB form could be suitable to turn all this stuff on and off automatically.
I've fitted about 25 of the Global stackers on a site with original cable only being aerial grade (about 10 years old single shielded,been told it wont work) and all have been perfect. But won't work with a wallplate or any joins in the cable. Brilliant bit of kit!
I guess I got away with a wallplate as it was made from an F to F joiner, thus a fairly "constant impedance" sort of join.
If you use the type of wallplate where you strip the cable and clamp the braid to a plate, and the centre goes to a screw terminal, then this is nothing like constant impedance, will look a bit like like a speed bump to the signal.
It's time to update my experiences with the stacker/destacker, because I suffered a failure. Well, it was probably always faulty, but it took the warm weather to show up the fault.
Global Invacom were very helpful indeed, sent me a replacement unit and I returned the dodgy one, and they duly sent me a copy of their engineer's report of the fault (poor solder joint).
But the main reason for posting again is that I learned a something more in my correspondence with them that probably should be in the instructions.
Without the included power supply, the Destacker will attempt to power everything (itself, stacker and however many LNBs you connected at the stacker - 2 in my case) from the receiver's LNB connections. This can be too much for some receivers. Especially as you might use the stacker/destacker to serve two receivers, but turn on only one of them.
My IPBOX is rated at 400mA per tuner, and I have reason to believe that (with the first stacker/destacker that I had, and the power saving scheme I had implemented whereby the AC power was switched on only when the receiver is on) then the LNB supply at one tuner input was actually collapsed with the overcurrent requirement during the fraction of a second that it took before the AC power supply took over, and then did not automatically re-establish itself. Of course if you just leave the stacker/destacker on AC power whether or not the receiver is on, then this can't happen, but at 9W drain this is a bit of an expensive option.
Happily it just doesn't happen with the replacement unit, could be it's just got a fractionally lower power requirement, or maybe I imagined it all, can't be sure at this stage. I'm just happy that it's all working well again.
I had SKY+HD box installed today but the engineer refused to go up on the roof where the dish is located (health & safety reasons!!) so he couldn't run two cables from the LNB. He said to get a de-stacker and feed the exiting one cable through the de-stacker and then connect two cables from the de-stacker to the Sky+HD box. Will this work or do I need a stacker attched to the dish. If I do need a stacker attached to the dish end then it slightly defeates the object because if you do this you may as well run the two cables.
If he'd been sent by 'Sly' to install then he was obliged to fit a Quad Lnb and run a second cable, in fact rmove the single cable and run a 'Double' down, I would be inclined to call sky and complain that it was not installed correctly.