Quattro signal puzzle

[RichardS]

I am setting up a multiswitch setup for a friend as a favour. I have purchased a Triax TD 78 with an Inverto Quattro Black Ultra LNB. Before I install the dish on his home I thought to try the dish and LNB at my own property.

I have a >10 year old Sky dish so I got some signal levels from it as a reference. However when it came to the 78cm dish while the dBμV levels are higher on all transponders the CNR is actually lower on some. The worst ones I tested were as follows:

Astra 2G:
11024 H - Sky LNB: 82 dBμV / 18.4 db CNR, Inverto 92 dBμV/ 13 db
11671 H - 72 dBμV/ 13.6, 88 dBμV/ 10.4

On 2E and 2F the European beams show lower CNR than the Sky LNB while UK beams have similar CNR to the Sky LNB.

Any ideas as to what the issue is here? I am a relative novice at dish installation so alignment may be at fault although I have tried specifically to aim the dish to maximise those 2G transponders and failed to even reach the Sky LNB CNR level. I am using a Satlink WS-6933 meter and am located ~ 30 KM north of Dublin in Ireland.

Thanks for any help.

 

[Channel Hopper]

Have you optimised the focal distance of the feed in the Triax clamp ?

 

[archive10]

Have you optimised the focal distance of the feed in the Triax clamp ?

And skew?
This has exactly the symptoms you describe. Even a degree or two can have effect.
But then again it may be different if you are more in the coverage of the footprint than I am - I am on the fringe...

 

[RichardS]

Have you optimised the focal distance of the feed in the Triax clamp ?

Thanks. Yes I have. The Inverto has a long neck and I have tried moving it both closer to and further from the dish to no significant improvement.

And skew?
This has exactly the symptoms you describe. Even a degree or two can have effect.
But then again it may be different if you are more in the coverage of the footprint than I am - I am on the fringe...

Yes I am aware of skew. The improvement is apparent but still does not reach the values seen by the Sky LNB. Thanks.

 

[Channel Hopper]

Ah, are you using the Sky LNB only on the Sky dish or are you able to move it over to the Triax ?

 

[RichardS]

Ah, are you using the Sky LNB only on the Sky dish or are you able to move it over to the Triax ?

I have another LNB, a single Lemon branded that I got free with a box years ago. I just tried it on the Triax and got CNR levels similar to the Sky LNB. So that leaves the Inverto.

I noticed that the dBμV levels were not as high with the single in comparison to the Inverto. Would it be possible that the high signal levels are swamping the meter leading to lower CNR? Although if that were the issue why is it not occurring over all transponders?

 

[archive10]

I have another LNB, a single Lemon branded that I got free with a box years ago. I just tried it on the Triax and got CNR levels similar to the Sky LNB. So that leaves the Inverto.

I noticed that the dBμV levels were not as high with the single in comparison to the Inverto. Would it be possible that the high signal levels are swamping the meter leading to lower CNR? Although if that were the issue why is it not occurring over all transponders?

Well, even Inverto get all their stuff manufactured and "tested" in China - I've had Invertos burn out on me before.
Even though the Inverto speaks very loud, I don't think your meter is overpowered - unless the meter is bad.
Insert 10db damping unit or 100 meter cable to check.
Otherwise just buy new LNB (Inverto if you like), claming the one you got isn't working as it should.

 

[RichardS]

Well, even Inverto get all their stuff manufactured and "tested" in China - I've had Invertos burn out on me before.
Even though the Inverto speaks very loud, I don't think your meter is overpowered - unless the meter is bad.
Insert 10db damping unit or 100 meter cable to check.
Otherwise just buy new LNB (Inverto if you like), claming the one you got isn't working as it should.

Thanks. I'll try to get an attenuator to confirm if the Inverto is at fault.