2.1 Dish and BBC2-ITV

[Captain Pugwash]

Hi everyone
Well I just joined this site and straight in with a Question.
OK so I live in The Czech republic and to get BBC & ITV ect I needed to get a 2.1mtre Dish. So I have and everything is fine except certain times of day I loose either The Beeb or ITV channels I have been told that this is something to do with the sat being just at the edge of the foot print at certain times during the day/night. My question is Can I improve this at all?? Maybe by getting a better LNB or maybe as I have seen on the front of a Sat mag 2 LNBs connected at the same time??? You see when I go out to the Garden and give it a tweak that usually does the trick
So I am not a pro and any advice would be greatly recieved
Ta very much

[Nick_UK]

What time of day do you lose the signal ?

[Chris Muriel]

If the mechanics of the system is set up correctly it should not normally need a tweak.
However dishes as large as 2.1 metres may gain a tiny bit of extra signal as the 28 degrees east postion isn't exact - the satellites themselves move around within something like a 50 Km cubed box ; larger dishes have narrower beamwidths but I haven't detected such differences on my 1.8 metre solid offset dish (which should have almost the same gain as a 2.1 metre prime focus dish) , except when I monitor the received levels accurately with a spectrum analyser (they are fractions of a dB different).
For a "normal sized" dish the satellite movement will not produce any measurable signal changes.
Other factors :
Noise figues of LNBs are bettter (lower) when cold, which ought to give better results at night.
Many satellites drop output power a little at night , when their solar panels aren't producing charge via the sun.
There could be some mechanical slack or play in your mounting / steering system, along with some hysteresis that may mean that it doesn't always go to exactly the saem position ; this assumes that you have a steerable dish and not a fixed one.

Chris Muriel, Manchester, UK

[Robbie34]

The only way really to improve the signal is to use a bigger dish. Possibly not the answer you'd like. There are LNB s that claim to have very low noise figures but they don't always give the results that they claim.

The Invacom 0.3db LNB has had good reviews, but some say they have achieved better results with the MTI 0.5db LNB. If you don't have either of these, and your LNB figures are higher, you could try replacing your present one with either of these. The MTI is cheaper.

Are you sure that your dish is correctly aligned and the LNB skew is right?

The only way to set up a dish properly is by using a decent meter. Try peaking it with a meter and make sure it is securely fastened once you have done this.

[Chris Muriel]

Originally Posted by Robbie34

The only way to set up a dish properly is by using a decent meter. Try peaking it with a meter and make sure it is securely fastened once you have done this.

Not true. Setting up using a spectrum analyser is far better than with a meter. Good installers (especially those who install a lot of steerable systems) , have portable spectrum analysers from Felec , Avcom, UnaOhm and others. You can instantly see what's happening and adjust skew properly (for minimum signal on the opposing polarity
which is the correct way to do this) with decent testgear.
Only problem is the cost of such gear. I got a couple of Felecs for 25 quid each (Ebay) but they don't appear all that often and I had to buy 5 and redistribute the others.

Chris Muriel, Manchester

[frund]

I agree with the above if you are fringe area you need the best LNB. also recheck your fine adjustments sometimes a minimal adjustment will make a noticable difference to signal gain.

[Robbie34]

Originally Posted by Chris Muriel

Not true. Setting up using a spectrum analyser is far better than with a meter. Good installers (especially those who install a lot of steerable systems) , have portable spectrum analysers from Felec , Avcom, UnaOhm and others. You can instantly see what's happening and adjust skew properly (for minimum signal on the opposing polarity
which is the correct way to do this) with decent testgear.
Only problem is the cost of such gear. I got a couple of Felecs for 25 quid each (Ebay) but they don't appear all that often and I had to buy 5 and redistribute the others.

Chris Muriel, Manchester

Of course, but be realistic. Are you going to advise someone with little knowledge to go out and buy a spectrum analyser in order to set up his dish properly? A cheap SLX Satellite Finder at £29 will do the job fairly adequately. I use a Digisat Pro - £69 - which will set up any dish more than adequately, but I would hesitate to suggest that the OP buy one for a one off operation. The SLX is worth buying as he'd probably save on the cost of employing somebody.

[Captain Pugwash]

Thank you all very much for your help
I have most certainly got some food for thought. I set it up myself and I now realise that I am more than a novice The Dish came with a sat finder thigimagig. It makes a noise and the light goes green when I have a signal. So I have been turning it down and adjusting bit by bit and each time turning it down a little bit more Oh well I am not sure which type of LNB I have but will look into that tonight. Thank you all once again and I will let you know the outcome
Cheers

[Captain Pugwash]

Originally Posted by Nick_UK

What time of day do you lose the signal ?

Usually when the weakest link is on
And comes back a few hours later. But I usally only have BBC1,2,3 and no ITV or the other way around Go figure???

[Chris Muriel]

Originally Posted by Robbie34

Of course, but be realistic. Are you going to advise someone with little knowledge to go out and buy a spectrum analyser in order to set up his dish properly? A cheap SLX Satellite Finder at £29 will do the job fairly adequately. I use a Digisat Pro - £69 - which will set up any dish more than adequately, but I would hesitate to suggest that the OP buy one for a one off operation. The SLX is worth buying as he'd probably save on the cost of employing somebody.

Agreed.
Change the word only to "normal" or "standard" and we'll call it a draw.

Chris Muriel, (currently in Boston area where larger dishes are somewhat commoner - BUDs = Big Ugly Dish)

[uk_jih]

I find that if the signal for BBC2 is bad, then it is usually better to watch BBC2 Scotland which has a bit of a stronger signal.

All programs that I record on BBC2 are recorded on BBC2 Scotland for this reason.

It is somewhere around channel 991 now.

[Nick_UK]

Originally Posted by Chris Muriel

If the mechanics of the system is set up correctly it should not normally need a tweak.
However dishes as large as 2.1 metres may gain a tiny bit of extra signal as the 28 degrees east postion isn't exact - the satellites themselves move around within something like a 50 Km cubed box ; larger dishes have narrower beamwidths but I haven't detected such differences on my 1.8 metre solid offset dish (which should have almost the same gain as a 2.1 metre prime focus dish) , except when I monitor the received levels accurately with a spectrum analyser (they are fractions of a dB different).
For a "normal sized" dish the satellite movement will not produce any measurable signal changes. ......

What Chris is saying is that the bigger the dish, the more precise you have to be when aiming it, and when you are aiming it at a cluster of satellites, then it's much more difficult. It's easier to understand if you liken a dish to a telescope - with a low power telescope, you can find the moon very easily, but you won't see much detail. With a much larger telescope, the detail on the moon will be much clearer, but you only have to knock the telescope by a gnat's whisker to lose the image completely.