Is a satellite internet dish different?

[dmaavrigdo]

Trying to put a second lnb for 15W on a dish that I got when I had satellite internet. Not having any success. I'm receiving 27w fine on the main lnb.
I've added second lnb on my main 28E dish before and it was done in minutes but on this dish this I've been waggling for hours.
Do they focus differently?

 

[Captain Jack]

Do you have a picture of the said LNB? Some operated at Ka-band, rather than Ku..

 

[dmaavrigdo]

Do you have a picture of the said LNB? Some operated at Ka-band, rather than Ku..

Both are universal lnb's. The satellite internet lnb is long gone. I just wondered if the dish focused differently.

 

[RimaNTSS]

I just wondered if the dish focused differently.

Of course, different offset satellite dishes have their focal points in different positions. But all of them have only one focal point, so only one LNB can be placed perfectly. All other, multifeeded LNBs will have worse reception capabilities. The distance between central LNB and multifeeded LNB can be different on different antennas.

 

[a33]

Trying to put a second lnb for 15W on a dish that I got when I had satellite internet. Not having any success. I'm receiving 27w fine on the main lnb.

Did you take into account that the multifeed skew between 27W and 15W, with 27W central, would be about 19 degrees for your location (60.51N, 14.225E)?

That is, 19 degrees against horizontal, perpendicular to the looking angle of the the 27W LNB.





Greetz,
A33

 

[dmaavrigdo]

Did you take into account that the multifeed skew between 27W and 15W, with 27W central, would be about 19 degrees for your location (60.51N, 14.225E)?

That is, 19 degrees against horizontal, perpendicular to the looking angle of the the 27W LNB.


View attachment 154837


Greetz,
A33

I didn't know about this, so now I am reading your posts from 2015 and on. I had just calculated the horizontal and vertical distances between lnbs and was trying to wing it from there..
Found a weak EXRN signal this afternoon but lost it while trying to improve it. Your admonition "Manual adjusting afterwards usually gives deterioration of signal, not better signal." turned out to be true.

 

[a33]

I didn't know about this, so now I am reading your posts from 2015 and on.

The exact calculation of multifeed skew is something I achieved only recently, though. It took me quite some time, also because in math I am also 'just' a hobbyist.
After deriving/developing the exact calculation, I was also able to adapt it to a much more simple approximate calculation. But then, when you can easily calculate the exact skew angle with a spreadsheet calculator, who needs an approximate...?

Greetz,
A33

 

[Channel Hopper]

I didn't know about this, so now I am reading your posts from 2015 and on. I had just calculated the horizontal and vertical distances between lnbs and was trying to wing it from there..
Found a weak EXRN signal this afternoon but lost it while trying to improve it. Your admonition "Manual adjusting afterwards usually gives deterioration of signal, not better signal." turned out to be true.

Many have suggested a spectrum analyser (of any brand/quality) as useful in the 15 years you have been a member. What have you tried and why are they not performing on a single satellite ?

 

[dmaavrigdo]

Many have suggested a spectrum analyser (of any brand/quality) as useful in the 15 years you have been a member. What have you tried and why are they not performing on a single satellite ?

I must have been lucky just using the signal strength display of my boxes or an app on my phone.
My f3/5 has a spectrum display but it wasn't doing me any good yesterday.

The formula I found for multi lnb positioning Fd(sqrt(2*1-cos(d))) gives a different separation than the one since found in an old post by A33 (0.01745*Fd*d*0.85) so I may have been starting from the wrong place.

 

[Channel Hopper]

I must have been lucky just using the signal strength display of my boxes or an app on my phone.
My f3/5 has a spectrum display but it wasn't doing me any good yesterday.

The formula I found for multi lnb positioning Fd(sqrt(2*1-cos(d))) gives a different separation than the one since found in an old post by A33 (0.01745*Fd*d*0.85) so I may have been starting from the wrong place.

A receiver spectrum display should be good enough.

The mechanical positioning can be carried out later, but you could try to improve things straight away with the feed distance and skew settings, one screw only on the feed clamp. Adjust for minimum signal on the opposite polarity to the one you are watching.

 

[dmaavrigdo]

The mechanical positioning can be carried out later, but you could try to improve things straight away with the feed distance and skew settings, one screw only on the feed clamp

If the lnb is in the wrong place how could I improve anything? Does it make no difference if the second lnb is 110 mm or 132 mm away from the first?

 

[a33]

a different separation than the one since found in an old post by A33 (0.01745*Fd*d*0.85)

I'm not sure where I wrote that? (And if I would still use the same calculation?)

My most recent approximation for the calculation of distance between LNBs is described in this "post":

Calculo Rapido de Caronas (3)

NUEVO CALCULO RÀPIDO DE CARONAS Aqui presentamos un metodo rapido de calculo, que es una variacion del metodo de calculo rapido de carona...

ftapinamar.blogspot.com

I never tested if 1.1 is indeed the best approximation for 1/BDF. BDF in literature is usually given as about 0.9 for offset satellite dishes, but I've never been able to reproduce that number from the mentioned equations, or seen that value tested in practice.
For effective focal distance I nowadays use distance from focus to deepest point of the dish (so not to the G-spot, anymore).

Nice that you seem to have "studied" these posts! There aren't many that do or have done that, from what I've noticed.

BTW. The calculated multifeed skew is, as far as my knowlegde goes, an exact and truthful outcome. When possible, I would first set that angle, and then "slide" the byrider LNB along that angle, to the optimal reception position.

Greetz,
A33

 

[dmaavrigdo]

I'm not sure where I wrote that? (And if I would still use the same calculation?)

Multifeed installation and exact calculation of LNB position

I have some questions about multifeed installation and multifeedbrackets, wanting to understand the principles behind it/them better. Q1. What is the best form of a multifeed bracket in the horizontal plane: straight, curved, … ? Of course in the vertical plane a multifeed bracket should mirror...

www.satellites.co.uk

 

[a33]

@dmaavrigdo
Ah yes, I remember that topic.
I've grown a bit in knowledge, I think, since then.

I would be curious if my new approximation calculation would lead you to find your byrider LNB position?

Greetz,
A33

 

[Channel Hopper]

If the lnb is in the wrong place how could I improve anything? Does it make no difference if the second lnb is 110 mm or 132 mm away from the first?

SImply because the analyser rarely lies. Once you have optimised the LNB for focal distance and skew, then you can start on moving the position across the arc knowing there will be only three parameters to play with.

 

[dmaavrigdo]

SImply because the analyser rarely lies. Once you have optimised the LNB for focal distance and skew, then you can start on moving the position across the arc knowing there will be only three parameters to play with.

Just put the lnb in a random position? Adjust the skew on a non-existant signal? Are we talking about the same thing?

 

[Channel Hopper]

Just put the lnb in a random position? Adjust the skew on a non-existant signal? Are we talking about the same thing?

You know you are looking for signals 12 degrees across the arc from 27W and I am assuming you have a single optics reflector, so no nothing different.

What should you be getting from 15W in Sweden based on your footprints and dish size ?

 

[dmaavrigdo]

You know you are looking for signals 12 degrees across the arc from 27W and I am assuming you have a single optics reflector, so no nothing different.

What should you be getting from 15W in Sweden based on your footprints and dish size ?

If it is on Euro spot 1 Satbeams says Recommended Rx antenna size: 38 cm, mine is 75cm. Azure Shine supposedly the VSAT model.
I'm now looking at the specs and the VSAT dishes have a longer FD than the DTH so perhaps a different curvature for sharper focus? Perhaps it is unsuitable for adding a second lnb after all

 

[Terryl]

What satellite internet service were you using???

And can you post a photo of the dish and it's mount.

I have used dishes from Wild Blue, I just mounted a universal LNB at the same location as the old LNB and it worked fine.

And some satellite internet dishes have a sharper focal area, this due to the fact that they have to transmit back to a satellite 22,500 miles away with less then a couple of watts of RF, so the front end may be less then 10 degrees on the prime focus area.

 

[Channel Hopper]

If it is on Euro spot 1 Satbeams says Recommended Rx antenna size: 38 cm, mine is 75cm. Azure Shine supposedly the VSAT model.
I'm now looking at the specs and the VSAT dishes have a longer FD than the DTH so perhaps a different curvature for sharper focus? Perhaps it is unsuitable for adding a second lnb after all

Ku or Ka model

Oddly their website has identical tolerances for the reflectors

75cm Ku Band – Azure Shine International Inc. 也翔國際股份有限公司

75cm Ka Band – Azure Shine International Inc. 也翔國際股份有限公司