ASTRA 2D BBC & ITV RECEPTION

[PaulR]

Mark

It's not my own drawing of the map but I would imagine it's drawn like that to show the relity of dishes up to and byond various sizes.

For very small (45 - 50cm) it's possible to get flat dishes as well as off-set types. Offset dishes are the rule up to a maximum of (I think) 1.2 metres. Centre feed dishes are available from about 90 cm all the way up to whatever your real estate and wallet can afford.

If you get enough signals with your 1.25m off-set dish stick with it. It's cheaper to maintain than a centre-feed type.

PaulR

 

[ugania]

I've got a 1,25 cm Emmeesse dish wich is quite good because here in Bologna,Italy, the 2d programmes are good most of the time, I have problems only after 11 at night for a couple of hours when sometimes the imagesfreeze. But I know that they make a 150 cm offset dish that you can find on their internet address and probably I'll buy it to watch BBC all the time for free and give up the subscription to Sky England and get Sky Italy with another dish I've already got

 

[methos_de]

Hi,

Just wanted to give an update on BBC reception in Germany. I now have a 1m cheapy solid dish and an invacom 0,3 LNB being used in Husum, North Germany appr. 50Km from danish border. I have all BBC and ITV channels 24/7 and also during bad weather which we "luckily" had today.

Methos.

 

[mikethebike]

Yet another problem to add to the endless list regarding 2D reception!
Since the BBC's changeover to 2D we've been watching BBC and ITV on a 1.2M offset dish which works perfectly well from about 9am until about 9.30pm if the weather is good, all BBC and ITV channels performing more or less equally during this time, appearing and disappearing together.
But knowing that winter is not all that far off and the weather here (between Bologna and Florence at about 700m up in the Apennines) is often misty and rainy we thought we should upgrade.
So a 2M prime focus dish was purchased, equipped with an Invacom 0.3dB quad LNB, and set up with a clear view of the sky at 28 deg E.
Astra was found easily, and some 2D channels, notably the vertical ones, came thundering in, and were perfect up until well after midnight (by which time the signals weren't fading out, I was!). But all 2d horizontal signals are completely absent - the Panny 20 declaring no signal the moment the channel is selected. Non 2D horizontal channels work fine, and two different receivers have identical behaviour.
I am aware that there is a difference in strength between H and V, but this much difference seems really strange to me since my 1.2M offset dish behaved identically on all 2D channels regardless of polarisation.
Does anyone have any similar experiences or suggestions?
Thanks
Mike
PS There is a polariser between the LNB (C120 interface) and feedhorn but it's open circuit so is not connected. I presume that this can't have any effect?

 

[rolfw]

I would guess that the polariser is more than likely the problem, with the very strong horizontal signals from the other transponders managing to fight their way through. Can you not get a feedhorn without a built in polariser?

 

[Old Fred]

Actually, I doubt if the polariser will have any significant effect. It may reduce the signal to the LNB by around 0.3dB but that's all.

Most likely what's happening is this: An LNB has a characteristic called "cross-polar isolation". I believe this is related to its ability to ignore or reject signals of the opposite polarisation to the one selected.

If the vertically polarised signals are very strong indeed, the LNB will be unable to reject them. It will in effect be "blinded" and unable to see the weaker horizontally polarised signals.

I guess an easy way to test this theory is to tape some pieces of cardboard or plastic over the feedhorn to reduce the signal from the dish to the level that the 1.2m dish was giving.

However, you should first optimise the LNB skew position by monitoring the signal quality in the "Manual Tuning" menu with the weaker transponder parameters typed into that menu.

This is guesswork based on what I've read (I'm not an installer) but logic tells me I'm not far off the mark.

Fred

 

[mikethebike]

Thanks for the fast feedback guys!
Actually it seems that Rolf is closer to the mark (sorry Old Fred!). As a simple test I tried rotating the polariser by 90 deg whilst maintaining the LNB orientation. Result: all horizontal channels coming in loud and clear, vertical channels non-existent, i.e. the inverse of the previous problem!
Clearly the polariser is the cause, but since I don't even know the make of the dish (bought secondhand via Ebay, and involving precarious dismantling on a Ravenna rooftop!) and there are no obvious markings anywhere, a feedhorn without polariser is not really on. I'll double check on this first of course, since it would be the easiest way.
However, the alternative will be to find out more about polarisers and how they work. I know they can be used to give skew control for peaking weak signals, but this one (two wire) reads open-circuit to a meter. Anyone know any links giving basic technical information on polarisers?

 

[rolfw]

If you have a digital camera Mike, take a photo of it, someone here may recognise it.

 

[mikethebike]

Good idea Rolf. These pictures should be self-explanatory.
If anyone can recognise the dish manufacturer, please let me know. I'm looking for a feedhorn without integral polariser.
Fingers crossed!
Mike

 

[britcoms9]

ASTRA 2D SUCCESS:

Equipment:
125 cm dish
0,3db Single Invacom

Location:
Potsdam, 1 mile away from Berlin

I received Astra 2D signal.
Receiving UTV and ITV2 with Sky Digibox (Grundig) was prossible, but with frequent disruptions (not 100% reliable).

No success with the BBC yet.

 

[BarMoo]

Success in Berlin! Hoorah!

Keep at the BBC and other missing channels and post back.

Do you have a 125cm offset dish? If so, what manufacturer?

Great news.

Mark.

 

[barney]

Good idea Rolf. These pictures should be self-explanatory.
If anyone can recognise the dish manufacturer, please let me know. I'm looking for a feedhorn without integral polariser.
Fingers crossed!
Mike

Hi, the feed is very similar to a FRACARRO FEED, but the dish is very, very similar to my 3mt dish(2 piece) manufactured by Pellini, in Veneto.
I've see in a photo 2 motor on your dish. Can the elevation motor help you to get a best signal for astra 2d, or it is only for inclinated orbit of old satellite in the sky?
Thank for your reply
Barney

 

[mikethebike]

Hi, the feed is very similar to a FRACARRO FEED, but the dish is very, very similar to my 3mt dish(2 piece) manufactured by Pellini, in Veneto.
I've see in a photo 2 motor on your dish. Can the elevation motor help you to get a best signal for astra 2d, or it is only for inclinated orbit of old satellite in the sky?
Thank for your reply
Barney

Thanks for your response Barney, very helpful. I've done a quick search on the net for Pellini but it seems they don't have a website - perhaps they don't exist any more? Same with Fracarro unfortunately. Do you have any contact details, or perhaps a dealer who sells their equipment?
Re. the installation, the elevation motor is just that - the dish was originally used with an Uniden SQ 550LT analogue receiver (not by me) which has two motor outputs, one each for azimuth and elevation. Since I'm not planning to look at other sats (just ASTRA 2A-D) I only used them to set up the dish alignment from the shade!
Best wishes
Mike

 

[rolfw]

Fracarro are still alive and kicking on the web. http://www.fracarro.com/operativo_es/installatori/ManSpTv.asp

May also be worth speaking to Iceman to see if one of his adjustable feeds would suffice.

 

[barney]

Thanks for your response Barney, very helpful. I've done a quick search on the net for Pellini but it seems they don't have a website - perhaps they don't exist any more? Same with Fracarro unfortunately. Do you have any contact details, or perhaps a dealer who sells their equipment?
Re. the installation, the elevation motor is just that - the dish was originally used with an Uniden SQ 550LT analogue receiver (not by me) which has two motor outputs, one each for azimuth and elevation. Since I'm not planning to look at other sats (just ASTRA 2A-D) I only used them to set up the dish alignment from the shade!
Best wishes
Mike

yes, pellini not is on the web.Also you can see www.irte.comfor feeds etc...
Ciao

 

[mikethebike]

yes, pellini not is on the web.Also you can see www.irte.comfor feeds etc...
Ciao

Thanks again Barney, but problem solved!
Taking another look inside the polariser I saw a metal collar (aluminium I think) with an elliptical slot, its end flush with the LNB interface (C120). Attacking with a drift from the feedhorn side (not easy!) brought the collar and polariser coil out (see piccy), and bingo - signals of both polarities come thundering in!
So thanks to Barney and especially Rolf for your help. I knew there had to be an explanation, but when you don't know what it SHOULD be like, it's all the more difficult!

 

[barney]

Thanks again Barney, but problem solved!
Taking another look inside the polariser I saw a metal collar (aluminium I think) with an elliptical slot, its end flush with the LNB interface (C120). Attacking with a drift from the feedhorn side (not easy!) brought the collar and polariser coil out (see piccy), and bingo - signals of both polarities come thundering in!
So thanks to Barney and especially Rolf for your help. I knew there had to be an explanation, but when you don't know what it SHOULD be like, it's all the more difficult!

Very good Mike.
When you are ok with your set-up, can you tell me this news:
1)the best trasponder of astra 2d
2)the hours when the signal is very strong
3)cable run
4) the skew of lnb is the same for other astra2a/2b or no?
Thanks for your help
Barney

 

[oggy9999]

Hi i live in South Germany about 70 miles east of Salzburg.
I have a 1 meter Dish and a Invacom 0.3 db lnb.
I can recieve BBC1 most of the time but it becomes a bit blocky in the Evenings.Same with ITV.
Thinking of going up to 1.25meter to improve things.
Ps the Invacom lnb did make a little bit of differnce over the 0.6 lnb what i had on before.Still not perfect in the evenings though.
Cheers Oggy.

 

[Old Fred]

Well I've learned something new! I thought that polarisers let ALL signals through but merely rotated them all by a number of degrees (up to 90') when a current is passed through the coil. But clearly they block signals of one polarisation. BTW the current required is normally anything up to 100mA (but more usually up to 50mA maximum). It's possible to make a simple one-transistor current controller for the purpose of manual control.

As for Invacom LNBs, I've heard that the twin- and quad-output versions work better than the single. Something to do with polar separation?

Fred

 

[roti01]

I've found a 1.8M FUBA fibreglass antenna. I understand from Corrigap's reports that he has suceeded with a 1.8M CM in Lund (S. Sweden, not far from me). I would be really grateful if anyone has any knowledge of these dishes and indeed whether I could fit an MTI 0.6dB LNB onto this dish before I buy it.

roti01

Well I've learned something new! I thought that polarisers let ALL signals through but merely rotated them all by a number of degrees (up to 90') when a current is passed through the coil. But clearly they block signals of one polarisation. BTW the current required is normally anything up to 100mA (but more usually up to 50mA maximum). It's possible to make a simple one-transistor current controller for the purpose of manual control.

As for Invacom LNBs, I've heard that the twin- and quad-output versions work better than the single. Something to do with polar separation?

Fred