LNB skew for Astra 2E/F

[Fredrik M]

I just fine tuned my dish a little to improve reception from Astra 2E/F. My target was to get the LNB position right. I am getting a little confused about the optimal skew angle for the new Astra 28.2 E satellites. It seems that I get the most optional reception if I set the skew to about -10 degrees. That is also what is also recommended by some internet sites, other sites claim that the Astra satellites at 28.2 are a special case in terms of polarization. For example Dish pointer claims the skew angle should be about -2.5 degrees for where I live, the polarization of the satellites being "pre-skewed". Is that really true also for the new satellites or was it just the Astra 2D? I dont get 2.5 degrees to work.

 

[RimaNTSS]

Rotate LNB till you get maximum signal. Just check it on both polarisations. Who cares about "pre-skewed" position?

 

[satelliteman]

Are you using a spectrum meter?

 

[Fredrik M]

No, I am not that high-tech. I am just using the signal meter in my Philips TV (and a sat finder for other adjustments).

 

[PaulR]

You're right that Astra pre-skew the satellites a bit so any predictor site that doesn't take this into account will be wrong.

Rima is absolutely correct - rotate the LNB for maximum smoke!

BTW, this pre-skewing means that people with steerable dishes will never get the maximum signal as the LNBs will be set for zero pre-skew.

 

[dungeon]

BTW, this pre-skewing means that people with steerable dishes will never get the maximum signal as the LNBs will be set for zero pre-skew.

So, what would be the skew that do you advise for a steerable dish to get the maximum signal. I am in Porto (North of Portugal) and I used to get a pretty good signal for all the frequencies in this satellite position (even for the UK beam), but I had to replace my LNB and now I am not being able to get a stable signal for any of the beams (I get a level of the signal of about 90% but the quality is very unstable (going from 77% to 0%) on those I can get the signal, because on most of them I don't even get any signal...

Any help would be appreciated.

Thank you.

 

[Lazarus]

The range of instability suggest more than a skew problem and could be indicative of a dodgy connection somewhere.

 

[PaulR]

Agree with Tivù that you might have another problem if you are getting swings like that.

With regards to what skew to set an LNB to on a steerable dish - it all depends on what your first priority is. If it's to get maximum signal on 28E then steer to 28E and rotate the LNB a bit for best signal. If it's to see what's on other satellites then set it to zero skew when the dish is at the top of its arc.

But really you should be thinking of a dedicated fixed dish for 28E when you're in a weak signal area. And then a second steerable dish to look at other satellites!

 

[dungeon]

The range of instability suggest more than a skew problem and could be indicative of a dodgy connection somewhere.

But I get stable signal on all sats that I get (from 39ºE to 30ºW)... I am only getting this problem on 28.2ºE satellites...

This is a video I made to show what happens... https://meocloud.pt/link/58bd6efc-2f8b-4b86-b256-a87a16628470/24032014051.mp4/

 

[Lazarus]

Ah, ok.

Is your line of sight obstructed in any way?

As for skew, then the best way to deal with this is by experiment.

The Astra 2 craft certainly used to be pre-skewed and to be honest I don't know if this applies to 2E and 2F, but if it does then PaulR's advice is sound, otherwise everything will be a compromise, which is not a good idea fro marginal reception.

 

[Lazarus]

Looking at your Video, I still think PaulR and I are right to suggest there is another problem: For the most part the fluctuation is normal, but the massive sudden drops are anomalous even for sub-optimal skew.

Is the cable from your LNB to the motor being dragged loose from the connection at the motor end when you pan towards 28E? This can be prevented by strapping the cable to something static (mounting pole etc) close to the motor (Assumes you have an H-H Motor? Photos might help us).

 

[PaulR]

But I get stable signal on all sats that I get (from 39ºE to 30ºW)... I am only getting this problem on 28.2ºE satellites...

Have you tried to set the skew for 28E when actually pointing at 28E yet?

Unfortunately I cannot view the video as I am work at the moment.

 

[dungeon]

Looking at your Video, I still think PaulR and I are right to suggest there is another problem: For the most part the fluctuation is normal, but the massive sudden drops are anomalous even for sub-optimal skew.


Is the cable from your LNB to the motor being dragged loose from the connection at the motor end when you pan towards 28E? This can be prevented by strapping the cable to something static (mounting pole etc) close to the motor (Assumes you have an H-H Motor? Photos might help us).

As per an obstruction at the line of sight, there is none - the dish is in a position that does not have that problem whichever the direction it is turned to. All the cables (motor and LNB are not streched in any of the satellite positions as they are fixed to the "ground". The motor is similar to the one attached (is this an H-H motor?).

I will only be able to post some close up pictures and make further tests next weekend. Until then I will have to keep waiting...

 

[Lazarus]

No, that's not prone to cables coming loose when panning.

And your line-of-sight is clear.

Doesn't leave us many options!

So, although I still think there is a loose/intermittent connection somewhere, for now I suggest you follow PaulR's repeated advice to adjust the skew with the dish pointing to 28E to see if it can improve the situation.

 

[sonnetpete]

I used to get a pretty good signal for all the frequencies in this satellite position (even for the UK beam), but I had to replace my LNB and now I am not being able to get a stable signal for any of the beams

Did you replace the LNB with exactly the same type? It is possible you have a faulty replacement, have you another you can swap over for it and see if the fault remains?

 

[archive10]

But really you should be thinking of a dedicated fixed dish for 28E when you're in a weak signal area. And then a second steerable dish to look at other satellites!

Totally agree.