quattro lnb problem?

[liveaboard]

I think this is a simple question...
Of course I could be wrong.
I have an invacom quattro lnb; I think it's faulty, but if that's the case then all 4 ports are equally defective.
The question is, is that likely?

I'm getting a very low signal, too low to do anything with. I'm pretty sure the dish is positioned ok, and others have said the signal should be strong at my location [intelsat 907]
VU + duo, both tuners show equal signal, swapped lines, swapped ports on the lnb, all equal.
It would seem that I have bad positioning, but I'm unable to get it any better. I’ve adjusted the frequency, polarization, and other parameters shown on the sat finder function.
I'm in Portugal with a 1.8 meter dish that used to work well with the UK astra satellites. The new tight beams have meant my setup has not been used for nearly a year; so I have no way of knowing if there is a hardware problem. It’s been raining a lot, water could have entered the lnb.
At the moment I can’t think of anything else to check.
There’s no one here to borrow a ‘test’ lnb from. I could have a pro come out to my place, but it’s an hour drive each way.
Thoughts?

[abu baniaz]

Quattro lnbs are designed to go to combiners. Each of the outputs only has a quadrant of the signal, you should still be able to receiver some channels.

If connecting directly to a receiver, you need a quad LNB.

[liveaboard]

Quattro lnbs are designed to go to combiners. Each of the outputs only has a quadrant of the signal, you should still be able to receiver some channels.

If connecting directly to a receiver, you need a quad LNB.

Thanks for the correction; Yes, it's a quad lnb, intended for 4 different receivers.
I only use 2 of them, each with it's own coax cable to the 2 tuners of the VU duo.

[adm]

Thanks for the correction; Yes, it's a quad lnb, intended for 4 different receivers.
I only use 2 of them, each with it's own coax cable to the 2 tuners of the VU duo.

A quad LNB has only 1 antenna but 4 channels of electronics. If the LNB is incorrectly positioned (including skew), or if the dish is of insufficient size all 4 outputs may show the same low signal strength.

I've stripped a LNB apart - photos at


http://www.admac.myzen.co.uk/quad_lnb/


The last photo shows the ONLY thing (antenna) in the mechanical horn of the LNB.

[liveaboard]

Thanks, I guess that answers my question. If there are 4 separate electronic packages, it's extremely unlikely that they would all be faulty; my problem must lie elsewhere.
The dish is way oversized [80cm is reported to work, I have 180], I have rotated the lnb [skew] with limited effect. After setting the elevation for the strongest signal, a check with my protractor/level shows the angle to be just as predicted; any side rotation causes complete signal loss. So it sure seems as if I'm oriented correctly.
I think I'll have to repeat everything to orient towards another satellite, maybe the one the Germans use. Just to see if everything works.

[abu baniaz]

Dont rule out damaged cabling.

[liveaboard]

Thanks, I did consider that. I don't see any damage, and there are 2 separate cables all the way from the dish to the receiver. They would both have to be damaged. There is no switch, and all intermediate connections are soldered.
Having said all that, we do have rats that sometimes eat wires... they caused some damage to my car and tractor.
Ate through an Aircon hose, lost all the gas... chewed right through the tach wire on the tractor.
Guess I'd better go into the attic tomorrow and check, but it seems unlikely.
Wife is allergic to cats, so that's a non-stater.

[liveaboard]

update;
No visible damage to the cables.
I tested the current draw, 210mA on each port which is correct it seems.
I found a huge spider nesting in the feedhorn; after removal, the AGC jumped from 40% to 85%, but the SNR is still at 15%
No changes in settings or dish position seem to budge it at all.

I might give up on satellite reception and go over to ip TV; it's all the rage here.

[Huevos]

Where are you exactly? If you are in the north near Galicia it is possible a 1.8m dish will work, but further south you have no chance.

[adm]

the AGC jumped from 40% to 85%, but the SNR is still at 15%
.

Local electrical interference? Another piece of electronic equipment operating close to your down-leads? Example, cordless phone (DECT) base stations placed very close to cables have been known to interfere with some satellite reception.

[liveaboard]

playing with the frequency had some effect; after much fiddling and searching, I figured out I'm on 30W hispasat.
Que "wall of Voodoo" "Mexican radio"...
search is now bringing in a lot of channels as confirmation.

Huevos. I'm in the western Algarve near Aljezur. Others have reported reception on an 80cm dish.
I'm trying to get intelsat 907
It's dark now, I'll try again tomorrow.

[liveaboard]

As the search finished, VIX crashed.

Second try, it works; I've even tuned in Aljazeera English

[liveaboard]

Having realigned the dish, I now have SNR 88% and AGC 69%.
Oddly, skew hardly makes any difference unless I rotate it about 90 degrees. and the signal stays strong when I move the dish a degree to either side, or up and down, or move the feedhorn in and out.
Am I right in thinking this is a likely indicator of a warped dish?
Anyway, plenty of signal this evening at sunset.

[adm]

Having realigned the dish, I now have SNR 88% and AGC 69%.
Oddly, skew hardly makes any difference unless I rotate it about 90 degrees.

Go to


http://www.dishpointer.com/


Enter your address/location
Select the satellite
You will get a map of your location, a line pointing to the satellite (which you can pick up the end point with your mouse and drag to your building)
Additionally you should get all the other technical information including skew (information shown below map). I believe that skew is much more important in fringe reception areas.

Portugal with the UK astra satellites skew is -25 to -29 degrees depending on your exact location. Perhaps you need to really fine tune before setting skew.

If you used a cheap satellite meter to set up the alignment the technique is once you have the satellite position you back of the sensitivity of the meter to get the fine tune position.


https://www.youtube.com/watch?v=9qMbbi2l9JA

Example meter


http://www.ebay.co.uk/itm/New-Digital-Satellite-Signal-Finder-Meter-With-LCD-Display-for-Sat-Dish-DIRECTV-/271779549670?pt=LH_DefaultDomain_3&hash=item3f4752d1e6

[liveaboard]

Yes, that's pretty much exactly what I did.
I stream the box output to my laptop so I can see the tuning meters on it up on the roof while I move things around.
As I said, I have a strong signal. it's just odd to me that the focus of the dish isn't more exact.
But I'm not getting the Astra satellites anymore, I'm moving it to 27.5W, intelsat 907