Jump to content

Parabole choice


Recommended Posts

I've decided to take the plunge and upgrade my 85cm dish to a 120cm version in anticipation of the forthcoming satellite change.

Browsing

the web reveals a wide spectrum of choice, ranging from cheapo 70€

steel units to 600€+ fibreglass ones, with mid-priced aluminium units in

between.

I'll discount the steel ones because they rust. I don't

want to appear to be a cheapskate, but is the vast price range on the

others really warranted? Am I right in assuming that reception quality

is very similar, regardless of price? Is it the quality of manufacture,

and thus durability, that makes all the difference?

I'm rather attracted to this one http://www.2galli.fr/boutique/fiche_produit.cfm?ref=OFC1100&type=30&code_lg=lg_fr&num=0. Any good?

I'm sure the experts will have advice as to what to buy; anyone else?

Cheers, Tony
Link to comment
Share on other sites

I can tell you from experience that you will need a "three point" fix. The problem is also alignment, it will have to be very accurate and every time you tighten things up it moves and everything needs to be very tight so as not to move in windy conditions. It took my guys a good 30 minutes to align and tighten everything up.
Link to comment
Share on other sites

Sorry for not replying sooner; been struggling with a water leak at the meter. Hopefully now fixed.

[quote user="Théière"]

How strong the mount is to resist the inevitable wind force with the larger dish is probably key. Your picture/link looked quite weak, more the size of a sky dish mount.

http://www.choozen.fr/ts-paraboles-satellites-110~antennes-paraboles-satellites,1010502.html

I thought from the picture these look more robust.

[/quote]

Thanks, T. You make a good point; it's not something I'd considered.

However, I don't understand your link, which points to 5 dishes, one of which is the one I'd selected, two others are the steel and ally grothers of that one, with the same mounts, and the rest don't show any mounts.

In another post, you refer to a "turnbuckle". What's that, and how is it useful?

Q, you refer to a three piont fix. Again, what's that, and how is it useful?

I think I have sufficient kit to perform the alignment; and the dish is a ground level.

Link to comment
Share on other sites

Hi Tony, sorry that was actually the wrong picture, the one I meant was this one showing the back mounting with bolts further apart and triangulate fixings to the fron of the dish possibly Q's 3 point mount?

http://www.2galli.fr/boutique/fiche_produit.cfm?ref=LABELAC115LX&type=30&code_lg=lg_fr&num=21

http://www.2galli.fr/boutique/images_produits/ac115lx-z.jpg

Link to comment
Share on other sites

What I meant was that you have three 'stays' to hold the LNB rather than just one as some have. This means when it is windy the arm holding the LNB does not move. Both dishes the engineers have used i.e. 1.2M and 1.5M all had a screw type system for fine attachment on the mount. Basically you get it almost right then use the screws to get it perfect. The other thing is that compared to my old 90cm dish these seem 'flatter' i.e. not so concave which makes them even harder to align hence the screw system for fine adjustment. The distance of the LNB from the dish is also quite important with bigger dishes, you can't just plonk it in and turn it round to the rough angle. I noticed by watching the guy set it up that around 1.5db could be gained by moving the LNB in and out from the dish. Further gains can be made by precisely changing the skew.

If you only have one of these meters that go inline to align the dish it might not be enough. The secret I have learnt by observation is quality not quantity. There seems to be a sort of wide band of power where the meter maxes out and somewhere in that band is the optimum signal quality.

The real annoying thing, even for these guys, that once spot on you tighten a nut and the thing changes slightly.

They seem to prefer resin' rather than metal although my 90cm dish was a Gibertini made of metal, quite light and had good write ups.

By the way my Inverto Black Ultra which everyone ranted and raved about certainly pulled in the signal but its signal quality was not as good as other LNB's in the same price band (i.e. under 20 Euros for a single)

Link to comment
Share on other sites

[quote user="Quillan"]What I meant was that you have three 'stays' to hold the LNB rather than just one as some have. This means when it is windy the arm holding the LNB does not move. Hence the picture above Q, I thought thats what you meant and the cheaper one in the link above seems from the picture at least to be more robust. 

 

I noticed by watching the guy set it up that around 1.5db could be gained by moving the LNB in and out from the dish. Further gains can be made by precisely changing the skew. 1.5db is a small amount

If you only have one of these meters that go inline to align the dish it might not be enough. The secret I have learnt by observation is quality not quantity. There seems to be a sort of wide band of power where the meter maxes out and somewhere in that band is the optimum signal quality.
That's why they have attenuating pot to reduce the signal level as you get closer, well mine does.
The real annoying thing, even for these guys, that once spot on you tighten a nut and the thing changes slightly. Hence why I mentioned turnbuckles as you could tension each side against the other

[/quote]

Link to comment
Share on other sites

Yes 1.5db (on quality not signal strength) seems quite small but when you are talking the difference between a picture pixelating at around 9.8db but OK at 11.17db signal quality the 1.5 becomes quite important.

I know the type of meter you have and the one I borrowed has a 'pot' to reduce power as you get the dish more aligned, I thought the all did. What I am trying to say, not very well perhaps, is that signal strength and signal quality are two different things and the the meter deals on in strength. The quality of signal is the more important out of the two and that is what one of these meters cannot tell you.

So far all the mounts I have seen use "U" fixings with just a bolt and nut to lock the vertical. The 1.2M and 1.5M both had a turnbuckle for the virtical. For horizontal movement they use "U" bolts but these two dishes had turnbuckles for fine vertical alignment as well. The reason being that as you tighten the nuts on the "U" bolts the things moves. The bigger the dish the smaller the movement to take it out of alignment. By the way th 'pole' to which they were mounted is much bigger that the one for the 90cm dish and is fixed top and bottom to the wall with very 'meaty' brackets.

Link to comment
Share on other sites

Thanks to both of you for your words of wisdom, and experience. It woulsd seem that I need to do further research into available dishes.

Certainly the steel ones are a lot cheaper, and given a fairly thin/flimsy steel plate, I can see why they they need a bigger support that the fibreglass ones, which would have their own rigidity built-in. Bum, I think I'm even more confused now!

Oh FYI, 1.5dB is  1.4 times the amount of power; hardly insignificant. Q is correct in discounting the little beeping device with a pot, which indicates signal strength. I have a (not inexpensive) gadget which, among other things displays signal strenght and quality. You can achieve good signal strength, over quite a range, but good quality (FEC ratio) comes at a very specific place therein.

Thanks again; I'll let you know how I get on.

Cheers, Tony

Link to comment
Share on other sites

Well both the 1.2M and 1.5M dishes the engineers bought are Epoxy, plastic or whatever, they are not metal that is for sure. The engineer as opposed to the technician seems to favour the 'plastic' ones and he seems to know what he is talking about. The other thing, in my case, is we got a better quality signal when mounted on the house wall just under a two story roof than we did ground mounted, about 2db in quality better. So as to make things quite clear we are 360M above sea level and the Pyrenees are right in front of us. They checked the angle with a laser (!) to ensure the peaks didn't block the view of the satellite and there are no trees in the way both on the ground and on the house wall. Hope that helps.

Link to comment
Share on other sites

[quote user="Quillan"]Yes 1.5db (on quality not signal strength) seems quite small but when you are talking the difference between a picture pixelating at around 9.8db but OK at 11.17db signal quality the 1.5 becomes quite important. I see, yes on quality it would be quite a difference as you and Tony stated below.

I know the type of meter you have and the one I borrowed has a 'pot' to reduce power as you get the dish more aligned, I thought the all did. What I am trying to say, not very well perhaps, is that signal strength and signal quality are two different things and the the meter deals on in strength. The quality of signal is the more important out of the two and that is what one of these meters cannot tell you. Yes agreed, only a starting point and I usually end up slightly lower in signal strength to get the higher quality signal, It sounds like Tony has the better gadget and not expensive, I wonder where from as they are generally a couple of hundred

So far all the mounts I have seen use "U" fixings with just a bolt and nut to lock the vertical. The 1.2M and 1.5M both had a turnbuckle for the virtical. For horizontal movement they use "U" bolts but these two dishes had turnbuckles for fine vertical alignment as well. The reason being that as you tighten the nuts on the "U" bolts the things moves. The bigger the dish the smaller the movement to take it out of alignment. By the way th 'pole' to which they were mounted is much bigger that the one for the 90cm dish and is fixed top and bottom to the wall with very 'meaty' brackets.
[/quote]

The angle from space is quite steep so you would have to be quite close to the mountains to not see the satellite and an offset dish could counter most situations? Off Tony's original topic I know but thanks for the info on the turnbuckles for the larger dishes, handy to know as I haven't needed a bigger dish yet........

[img]http://www.satsig.net/22-deg-offset.gif[/img]

Link to comment
Share on other sites

  • 2 weeks later...
Just to wind this up, I got the 120cm epoxy dish I originally referenced; the bracket is in fact far from flimsy; 1.5mm pressed steel; with reinforcement within the epoxy. The dish is quite stable.

Aligned it with my ws6909 meter, and now have all the freesat channels back again. High hopes for when I get back here for new year!

Thanks all for your help!

Cheers, Tony

Link to comment
Share on other sites

Nice Tony and thanks for reporting back, you just can't tell from a photo how well or even if it's the actual product being sold these days but it sounds good from your description.  I picked up a positioning motor the other week so I may mess around with that and see what other free channels I can get. 
Link to comment
Share on other sites

[quote user="Quillan"]Just as a matter of interest somebody said the other day that 1M is the biggest you can get without planning permission, is this true?

[/quote]

No doubt someone will come along to correct me, but I believe that only applies to a dish mounted high up (to ensure it won'nt blow down onto someone's head!). If it's at ground level, you can do what you like.

Link to comment
Share on other sites

I had a spare 30 minutes and had a look on the Legifrance website and could not find anything. As you say perhaps somebody else might be able to point me in the right direction. Where is Clair when you need her, she is pretty good at finding these things. [;-)]
Link to comment
Share on other sites

Could not find it in the official law as it dates from 1966, but you need permission above 1 meter diameter according to this article here.

" Si vous êtes propriétaire d'une maison, vous n'avez pas besoin d'autorisation pour poser votre parabole si elle mesure moins de un mètre de diamètre.

Au-delà, une déclaration de travaux à la mairie est obligatoire."

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...