Help, Got myself 1m dish

Genie

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My Satellite Setup
DM800 with 320GB HDD running Nabilosat 0.12
1 metre motorised dish. Intel core i7 920 PC
My Location
London
#1
Please help.

Following advice on the forum, I opted to get a 1 meter dish instead of an 80cm. I also bought a double digistar universal monoblock lnb (anyone heard of it). rating 0.7, So that I could pick up both Astra and Hotbird. This is a two lnb's in one with just one output and a built in DiSeqC switch.

Now I connected it all up and installed it. I found the Hotbird signal by connecting it up to my analogue receiver and moving the dish until I got an acceptable signal. The analogue receiver does not have Diseqc, so I dont know which LNB the signal was coming from.

I search for channels on my Hauppauge WINTV DVB-s card and it picks up most of them on HotBird, but some signals register too week and the channels are not found, like Dubai TV. Others are fine like Bloomberg UK, and Sky News. Why is this, could the Dish need fine alignment? Does the LNB have to fit in the arm fully or at the end, i.e closer to the dish or further away.

The other problem I am having is when trying the search for Astra channels I am not getting anything. How can you tell what type of diseqc the LNB has built in. I have set it to mini Diseqc in the receiver. Could it be diseq 1.0. On the lnb box it say diseqc 2.0, but that does not make any sense, cos' I've not heard of that one.

I dont know if the left or the right lnb is giving me signal with diseqc off. If I knew I could align the dish accordingly. How can you tell?

Could it be that The dish is too big and collecting too much and that the LNB will only work with 80cm because of its fixed offset?

:-(
Please Help.
 

2old4this

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#2
first off, you don't say where you are situated. For all we know you could be on the edge of the footprint of the beams you are struggling with and that would certainly explain marginal reception.

The monoblock, just like all multi-LNB arrangements, causes for at least one of the satellites the signal to be picked up away from the primary focus of the dish. After all, the dish has only one optimal focal point and you need to squeeze two out of it. So this meas that the signal received will always be a bit weaker than if you had a single-LNB arrangement. Depending on how you have aligned your dish and mounted your monoblock, either you will be focussed on Astra, or focussed on Hotbird, or focussed on a position in between.

A 1m dish and 0.7db LNB should not produce a signal that will overload your tuner.

My advice: tune to the weakest of all the signals you have, then align the dish to optimise that signal.

The LNB needs to sit at a very specific distance from the dish. If you are using an arm which came with the dish, then that should already be catered for. If you have cobnbled this together from different parts, you'll need to check the arm's length against the dish's focal length and modify the arm accordingly.

DiSEqC v2.0 is not an official protocal yet I believe. But the simple 2-LNB monoblock will presumably be compatible with all versions of DiSEqC since the later versions only added support for steerable systems and switches for large numbers of LNBs.

It doesn't really make sense to talk about the signal being picked up from one or other LNB while DiSEqC is "off". DiSEqC is simply a command protocol. When the switch receives a certain command from the receiver it switches in one or other of the LNBs accordingly.

2old
 

Genie

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My Satellite Setup
DM800 with 320GB HDD running Nabilosat 0.12
1 metre motorised dish. Intel core i7 920 PC
My Location
London
#3
Sorry,

I'm in London.

When connected to an analogue receiver with no DiSeqC control, I get hotbird signals, so I don't know which LNB is producing the signal, is it usually the left or right one (when looking at it as if I was the dish face) that is the default (Sorry for being silly, I'm new to this). I'm using the analogue reciever just for dish alignment.

Are Monoblock LNBs designed just for 80cm Dishes?, ie. due to the arms length and calculated fixed offset to each other?. From my digital Receiver software should I select mini DiSeqC (simple disiqc) or Diseqc 1.0?

The arm is the one that came complete with the dish.
 

2old4this

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#4
In London, 1m should be sufficient for all signals, even on a monoblock arrangement.

There is no "default" left or right LNB which picks up the signals.
To understand what's going on, you need to visualise where the satellites are in the sky, and what is happening to the signals as they are reflected from the dish to the LNBs.
For those of us in the northern hemisphere, the Hotbird cluster of satellites (13 degrees east) appear to the right of the Astra1 cluster (19.2east).
The dish should be aimed between the two - at 16east.
Then, the signal from Hotbird comes down from the right and is reflected by the dish to the left.
The signal from Astra comes down from the left, so is reflected by the dish off to the right. Therefore, looking upwards from the dish to your monoblock, it is the right LNB which receives Astra, and the left one which receives Hotbird.

But imagine that you (mis-)aligned the dish too far left (east) so that both Astra and Hotbird were "on the right". In that case, both signals would be bouncing in from the right and be reflected off to the left. The result could be that the Hotbird signal misses the monoblock altogether, but that the Astra signal finds the left LNB that normally would receive the Hotbird signals. So you need to be careful.

If I were you, I would use a simple-stupid method of making sure the signals you are getting are on the "correct" LNB. Simply obscure one of the feedhorns (place something over the front of one half which is opaque to microwaves - such as a damp piece of cardboard). Then you KNOW that any signal you can get is coming from the OTHER LNB, and can derive conclusions on which DiSEqC setings are doing what - as well as whether your dish is aligned (if you blocked off the right LNB and still got Astra you know your dish is too far to the left).

2old
 

rolfw

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My Satellite Setup
Technomate 5402 HD M2 Ci, DM7000s, Transparent 80cm Dish, Moteck SG2100 DiseqC motor, lots of legacy gear. Meters: Satlook Digital NIT, Promax HD Ranger+ spectrum analyser.
My Location
Berkshire
#5
Yes as 2old says, if by blocking off the right hand Lnb (looking from behind the lnb toward the dish) the hotbird signals disappear you are lined up on the right bird and will need simply to allocate a DiseqC number of 1 or 2 to the 19.2 satellite for it to activate the switch, the 19.2 channels should then be available.

If the hotbird channels do not disappear, then you will need to swing your dish around to the east to find 19.2 and then allocate a 1 or 2 diseqc number to the hotbird satellite.

Diseqc 1.0 should be adequate to operate the monobloc.

Rolf
 

Genie

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My Satellite Setup
DM800 with 320GB HDD running Nabilosat 0.12
1 metre motorised dish. Intel core i7 920 PC
My Location
London
#6
Thanks 2old, You're a genius.

I'll be doing that on the weekend. And I'll probably then make the left lnb the prime focus (for hotbird) and the right one will set as offset (Astra).
 
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