Advice Needed Reduce interfering satellite

AtOM13

AtOM13

Member
My Satellite Setup
Sedea 80 cm, 1w 13e 19.2e Inverto black ultra LNB
Laminas 150 motorized 47.5w to 76.5e Megasat Diavolo + scalar ring
Channel Master 1.8m
My Location
South France, North of Marseille
After many hours of searching and testing, I think that 5w beam is interfering with 8w Mena beam here.

I can lock easily frequencies over 12...mhz with 13 db on 8w MENA beam, but 11...mhz frequencies reach only 4db !
( 6.6 db C/N lock )

11013H and 11054H are very important for my Bein satellite subscription.

I'm living near Marseille, in south of France, close to Italia and 5w beam is powerful here. I noticed that @stephan94 who's living in Bavaria, also not so far from Italia got similar problem.

In the same time, members located in west of France, England, Belgium etc... lock easily 11... mhz frequencies !

Referring to @william-1 post, some members in England have similar problem with Badr 26e and Astra 28.2e:

Just Sharing This - Badr-4 reception

And @hvdh talked about a possible solution for this problem:

hvdh said:
Over 10 years ago, sat dx'ers were struggling to get 2 Russian transponders of 40°E Express-AM1 with 100...120 cm dishes.
Interference came from both sides: 39°E and 42°E.
By placing small PVC pieces in front of the LNB, the interfering satellites were suppressed enough to get reception of 40°E.
Maybe it will work in this situation as well (23.5°E - 26.0°E - 28.5°E).
But in this case it probably must be shorter, because the satellites are less close to each other.
Note that it could only benefit a fixed installation, because the piece causes some attenuation in the main direction as well!
Grabbed below picture from dxtv.de (deepbluesky).
I still have such PVC piece laying here, it's 5 cm diameter, 2 cm long, with two cut-out gaps of about 30°.
View attachment 128562
Click to expand...

Someone already have this problem and find and solution ?
 
What size dish are you using for 8W? Bigger dishes have narrower beamwidths so they are less likely to get interference from neighbouring satellites.

But it could also be that the 12GHz transponders just have a better footprint for your location. Maybe the official footprint maps aren't quite so accurate?
 
@AtOM13
Could it be that the interference you experience is not from a nearby satellite but from the opposite polarity?
I noticed that the frequencies you mention (also in another thread) have both polarities in use, on the same beam.
It could be cross polarisation if the skew of the LNB is not correct. I would take a look at that.
Maybe another LNB, with better cross polarisation suppression could make the difference?

How did you measure the C/N? From the spectrum or from the resulting S/N or MER?
 
@timo_w2s Actually Laminas 150 and Megasat Diavolo lnb. Also tested with CM 1.2m, Triax 1m... and test before with lot of others LNB...
And yes I can confirm that official 8w Mena footprint is not accurate at all !

@Old Satterhand yes I tried to adjust skew, also tried lot of others LNB :(
The C/N lock data came from Lyngsat and only parameters that I can read with my Os Mio+ are SNR and AGC (when lock)

Here is a map with some members reports on 10971V :

1000075234.webp
 
timo_w2s said:
What size dish are you using for 8W? Bigger dishes have narrower beamwidths so they are less likely to get interference from neighbouring satellites.

But it could also be that the 12GHz transponders just have a better footprint for your location. Maybe the official footprint maps aren't quite so accurate?
Click to expand...
Footprints won't have an impact on reception, the orbital slot is usually accurate to under 1/10 of a degree.

What may impact on interference are sidelobes of an adjacent satellite, and this can be down to a mismatched feed to the dish, incorrect focal distance or a warped dish.
 
AtOM13 said:
yes I tried to adjust skew, also tried lot of others LNB :(
The C/N lock data came from Lyngsat and only parameters that I can read with my Os Mio+ are SNR and AGC (when lock)
Click to expand...

Have you ever tried another receiver? There are big differences between them when receiving out-of-footprint signals.
And in general, avoid using LNB's with over 60 dB conversion gain (like some Inverto's) in combination with bigger sized discs.
 
Last edited:
Yes already tried with 2 others receivers :(
 
Did you try any 40 mm (head diameter) LNB, to narrow the angle of the disc?
That would give you a better separation from adjacent satellites, probably at the cost of some signal loss.
 
All I can think of is a different dish with a narrow receive beamwidth and a tight LNB, the 5W beam is of a much higher signal strength then the one you want as your not in 8W's footprint, have you tried offsetting the dish further to the west a bit?

You might loose signal on the one you want but that could be compensated by a bigger dish. (with a narrow front end)
 
AtOM13 said:
This kind of lnb ? :

www.satshop.uk

Inverto 23mm Narrow Neck Universal Single LNB

Inverto 23mm Narrow Neck Universal Single LNB
www.satshop.uk www.satshop.uk

@Terryl yes already try offseting dish :(
Click to expand...

Yes, or any other multifeed LNB with a smaller feedhorn.
That, combined with offsetting the disc further from 5W, could be a solution.
If that doesn't help, you know that interference from 5W is not the culprit.

Only a spectrum display (of the low band IF signal) can reveal the cause of the low SNR.
 
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