No BBC - or alternatively, no ITV

[Araucaria]

Can someone help me (and maybe save me the €40 call-out fee for my local TV professional)?

We have a cheap set-top box (branded PMB, probably Chinese) and I'd guess a cheap dish too (55cm diameter), but it used to get us all the free-sat channels from (I think) Astra 2B.

Now it will only get a limited selection: most BBC channels, and Ch 4 and Ch 5, though not BBC News, and no ITV channels.

After a thunderstorm last week I had to replace the LNB head, and I noticed that the head has index marks and that you can turn it and presumably make a minor alteration to the direction the set-up points. By trial and error I found that if I turned the LNB head quite a long way (beyond the index marks) I could get ITV2 and ITV3 (and probably some other channels too, I didn't check), but NOT the BBC etc channels listed above. If I turn it back to the central indexed position it's BBC and not ITV.

This problem dates back to before the thundertorm.

I didn't want to start playing about with the direction the dish points in case I lost the limited number of channels I had. But I can't understand why I can get some channels from the satellite but not others. Can anyone explain? And should I just try re-directing the dish?

[Anton Redman]

You are receiving your signals from four satellites which move in a cluster inside a large cube in space.

If you have a friend with UK TV the first thing I would do is to try your receiver on their dish and their receiver on your dish. If you receiver shows the same problems at your friends and their receiver works perfectly at your house then the receiver probably needs replacing. Either another cheap receiver from a French supermarket or better still a cheap UK freesat receiver from UK.

You may still find you need to upgrade the dish size.

If you receiver is OK at their house then you probably have an alignment problem. Try the menus on the remote control till you find one that displays sighnal strength and quality.

Fine tuning the dish alignment. Before you start moving any thing. Mark the elevation on the dish with a paint line or scratch so that you can recover the same position if every thing goes wrong. Walk down the garden at least 10 metres and hammer a stake into the ground so you can find the exact angle if anything goes wrong.

Wait for a dry day if possible and take your receiver and a small portable TV outside so that you can see them as you move the dish by minute amounts. Maximise the signal strength then quality a channel: Move the dish up and down and left to right by minute amounts first maximising strength then quality.

Lock the position then move the LNB clockwise or anticlockwise and also in and out again concentrating on quality

One other thing you can try is to google ‘Lyngsat’ and see if there is anything that is common about the channels you can and cannot receiver. If they are all ‘Horizontal’ and none are ‘Vertical’ then either the LNB or receiver has a problem. Ditto if they are all high or low frequencies. If H & V is the problem if you turn the LNB through 90 degrees you should swop the channels you can and cannot receive.

[Araucaria]

Thanks Anton

I will try your "swapping receivers" suggestion as soon as doing so won't disrupt our friends' viewing too much.

I didn't appreciate that the signals came from more than one satellite. Presumably although they aren't actually rubbing up against each other, they are sufficiently far away for the dish to get all four at the same time.

I'm not so sure about "staking out" the present azimuth position of the dish. It's quite high up a wall and the ground drops away below it for several miles. From where it is, it has a nice view of the sky and the other side of the valley, so I'd need a very tall stake. Perhaps I can line it up with some landmark in the distance. The elevation can be marked, of course.

My main problem is that the instructions for the receiver appear to have been written in Chinese before being translated into English (and French), and they are the next best thing to unintelligible. But your suggestions are helpful.

[AnOther]

There is usually enough 'give' in the support bracket to allow a bit of manual twisting in search of a better signal without having to release anything so I would try that first and only actually adjust it if such tests point to it being necessary. You will also know which way it needs go too [;-)]

[Anton Redman]

Stakeing - broadly you walk away down the lnb line so the are looks like it is pointing at you

[Frecossais]

Our method of aligning our sat dish involves OH up the ladder on the roof and me in the house screaming, "Nochangenochangenochange worse nochange grainy betterbetter no, worse again,"etc etc. until somehow we hit the spot.

We have done this a few times now and I am becoming good at it.

[Anton Redman]

Bit like a version of 'The Golden Shot' filmed in an asylum.

[Gyn_Paul]

Just one little thing to add...

It sounds like the OP's installation was not done by him so he may not know that with digital receivers it's important to allow a few seconds after any adjustment for the circuits to 'digest' the new signal information. With a Sky box, for example it can be up to 3 seconds after moving the dish before there is any change to the signal bars. So if you move to much, too quickly you can pass through the 'sweet spot' without noticing it.

Some are worse than others. My Euro1080 receiver, for example, seems to take a God's age before telling me I've got the dish back on target.

Speaking of which...

Can anyone help me source either from France, or on the internet, aerial mast brackets. I'm looking for a bracket which will connect a vertical pole (lashed to the chimney) to another vertical pole (the rt-angle pole out of the back of a dish). but it must have teeth to grip, as the bracket I have at the moment has only depressions to vaguely centre the poles, and no matter that I tighten the thing enough to bend the steel, it still gets blown off station  in a storm.

p

[Frecossais]

[quote user="Anton Redman"]Bit like a version of 'The Golden Shot' filmed in an asylum.[/quote]

[Frecossais]

[quote user="Anton Redman"]Bit like a version of 'The Golden Shot' filmed in an asylum.[/quote]

Close.

[Frecossais]

Sorry, my smiley didn't come out. I'll just try again:[:)]

I wanted the yellow one. Will read up on this.

[Anton Redman]

Have a look at 'Shelley Clamp' about half way down the page the google . Try Pro & Cie for something similar or have a look at Exhaust clamps ?

http://www.satcure.co.uk/accs/page2a.htm#ubolts

[Robin]

Hi Araucaria,

I'm new here and maybe you've solved yr problem.

I offer you 24 yrs experience of fiddling with dishes and receivers.

Your symptoms suggest that you are only getting one of the H/V polarisations and since you changed the LNB after the orage, it points to the receiver having a fault, or less likely, the cabling.

Sat tranmissions have horizontal and vertical polarisations. Terrestrial is usually H (antenna mounted flat) but sometimes you see V from local transmitters. For sat, both are equally exploited to avoid adjacent channel interference.

You swivelled the LNB in its mount by "quite a long way" and by doing so, you went from H to V (or V to H). This switching is normally done by yr receiver sending either 13.5V or 17V to the LNB. I guess that bit isn't working in yr receiver.

You can do a test.

C4 is on H and C4+1 is on V, so if my diagnosis is partly right, you will get one and not the other.

If you have a freesat receiver, then at some stage, you typed in a postcode so that the receiver chooses the BBC & ITV for yr area.

BBC1 London is on H but BBC1 East Yorks is on V. Try London and Hull postcodes and see if one works and not the other. (The polarisation postcode police will not knock on yr door).

That is my likely diagnosis. There are other possibilities.

1st; yr 55cm dish is a bit small for Auverne. I had 55cm in Wilmslow and upped to 90cm in Languedoc. You can never have a dish that is too big although a Jodrell might burn out yr receiver input.

2nd; there have been some changes in last weeks, TV companies switching to transponders that are more tightly focussed on UK. I thought this was just a HD thingie, but they play with this all the time. This might have caught yr smalsh dish out.

So what do you do?

With the receiver off, pull the cable from LNB and check the plug integrity. It might need tightening. I doubt this, cos if the wire ships 13.5V it will ship 18V. It's only electricity.

As suggested by others above and it is always a very good move, try a different receiver. If that works, time to dump yours NOW. It is not worth wasting time or money on something that is unbelievably cheap, given what it does, like pick up signals from a transmitter running on the power of a lightbulb, 24,000 miles away.

Chinese electronics are both cheap and good quality. Apple use them. They have the world by the throat.

If a different receiver shows the same symptoms then I shall be staggered, but that still leaves the cabling and the LNB. But you swappped LNBs so it means the cabling.

best

Robin

[sid]

Good post, Robin... and welcome to the forum.

[Robin]

Thank you Sid.

I looked at a few forums and I liked the attitudes here.

There is one where folk moan because the local tax office can't/won't speak English. What abt the Germans, Belgians, Dutch, Spanish and Italians?

It's one of 57 reasons I came here, to stop paying taxes which get used to pay expensive interpreters for those who won't learn the language. Altho I bet English local tax offices don't discuss tax law in French, German etc. . .

[Anton Redman]

Very good idea on C4 and C4+& for testing if polarity switching works