dual lnb

[steddie2.5]

Re: dual lnb

So if i want a duo lnb setup do i need to decide which satellites i want to recieve before i buy the lnb or can i go for any pair upto a maximum angle apart. Any good sites to look for these lnb's ??

Re: dual lnb

Actually this is not true. First of all, you would not need a twin LNB for that, a single LNB would be sufficient as the tuning is done at the receiver and the receiver doesn't care where you are pointing. But more fundamentally, your thinking is wrong. The bigger the dish, the better the focus, the less side lobes. You won't get anything from Astra 19.2E if you have a 10m dish pointed at hotbird 13.0E or even pointing somewhere in the middle between the two! In fact you have to re-point a 10m dish if you switch to a transponder on a different, yet co-positioned, bird! That's how they keep'm co-positioned without bumping into each other in the first place.

You could, of course, take a hammer and flatten the dish. That would do the trick, as it ruins the focus, but it would also be a complete waste of money!

You have better chance of getting something on both Astra and Hotbird using a smaller, say 30cm dish, pointing towards 16E. You'd get powerful transponders only, of course.



That depends on what you want. They should not be too far apart, otherwise you'll need two separate LNBs and a bracket. Also, the further apart, the better your dish should be. Adding more LNBs, either a duo/triple or on a bracket, requires a larger dish, as the LNBs will be sligtly out of the main focus where the mirror works best. Also the effective surface of the dish as seen from the LNB is reduced proportional to the cosine of the angle that separates the 'secondary' LNB from the center of the dish. On the picture posted by yselim you'll notice that the dish is actually specifically made for use with multiple LNBs, as it is stretched horizontally.

Duo (rather than 'twin') and Triple LNBs are available in different forms, and they are mostly marketed by content providers (Sky, Canal+, Canal Digitaal, ABSat, DIGI etc) who want to offer a broader package. Triple LNB's for 28.5E/23.2E/19.2E are readily available in Holland. In Germany you can find cheap Duo LNBs for 19.2E and 23.2E, in Italy they prefer 19.2E and 13.0E Duo LNBs, etc. etc. It all depends on what birds the main providers of that country are broadcasting from.

Also note that a Duo LNB that would capture Astra 19.2E and Hotbird 13.0E in Norway would be slightly different from a similar device in southern Greece, as the required angular spacing between the heads changes with the lattitude. You can use whatever satellite positioner software to calculate the exact angular spacing from your geographical position (******: '****** earth sat finder') and use that as a guide for what Duo/Tripple LNB or bracket to buy. In general the extra loss introduced by misaligning less than 0.8 of a degree is neglectable. Over 1 degree becomes noticable, specially in bad weather and when snow is accumulated on the dish itself.



The CAM actually adds to the delay introduced by the rotor. On my motorized dish switching between encrypted channels on 19.2E and 23.2E sometimes takes up to 17 seconds. On my other dish, that has a duo LNB at these birds, it is almost always instantaneous (i.e. less than 2 seconds, which is not bad for encrypted HD channels!) This is because with the rotor, the CAM is without signal for some time, which requires it recalculate a DCW, whereas with the Duo LNB the same DCW can be used.

However, to make the choice even more complicated, one must not forget that 2 or more separate LNB's requires a Diseqc switch, which is -most of the time- already incorporated in a duo or triple LNB.

I've complete forgotten about Diseq, anyway we have to tell that is needed only when you connect same reciver to two sattelites, if you have a reciver for each you don't need diseq

[astr1d]

Re: dual lnb

Yes but it can also be used on two sattelites if you have a big dish, but like i said with poor results on one of them

Actually this is not true. First of all, you would not need a twin LNB for that, a single LNB would be sufficient as the tuning is done at the receiver and the receiver doesn't care where you are pointing. But more fundamentally, your thinking is wrong. The bigger the dish, the better the focus, the less side lobes. You won't get anything from Astra 19.2E if you have a 10m dish pointed at hotbird 13.0E or even pointing somewhere in the middle between the two! In fact you have to re-point a 10m dish if you switch to a transponder on a different, yet co-positioned, bird! That's how they keep'm co-positioned without bumping into each other in the first place.

You could, of course, take a hammer and flatten the dish. That would do the trick, as it ruins the focus, but it would also be a complete waste of money!

You have better chance of getting something on both Astra and Hotbird using a smaller, say 30cm dish, pointing towards 16E. You'd get powerful transponders only, of course.

Which pairs of satellites can I get if i go down the twin lnb route?

That depends on what you want. They should not be too far apart, otherwise you'll need two separate LNBs and a bracket. Also, the further apart, the better your dish should be. Adding more LNBs, either a duo/triple or on a bracket, requires a larger dish, as the LNBs will be sligtly out of the main focus where the mirror works best. Also the effective surface of the dish as seen from the LNB is reduced proportional to the cosine of the angle that separates the 'secondary' LNB from the center of the dish. On the picture posted by yselim you'll notice that the dish is actually specifically made for use with multiple LNBs, as it is stretched horizontally.

Duo (rather than 'twin') and Triple LNBs are available in different forms, and they are mostly marketed by content providers (Sky, Canal+, Canal Digitaal, ABSat, DIGI etc) who want to offer a broader package. Triple LNB's for 28.5E/23.2E/19.2E are readily available in Holland. In Germany you can find cheap Duo LNBs for 19.2E and 23.2E, in Italy they prefer 19.2E and 13.0E Duo LNBs, etc. etc. It all depends on what birds the main providers of that country are broadcasting from.

Also note that a Duo LNB that would capture Astra 19.2E and Hotbird 13.0E in Norway would be slightly different from a similar device in southern Greece, as the required angular spacing between the heads changes with the lattitude. You can use whatever satellite positioner software to calculate the exact angular spacing from your geographical position (******: '****** earth sat finder') and use that as a guide for what Duo/Tripple LNB or bracket to buy. In general the extra loss introduced by misaligning less than 0.8 of a degree is neglectable. Over 1 degree becomes noticable, specially in bad weather and when snow is accumulated on the dish itself.

Yes but we talk about few seconds, sometimes a CAM server takes long to send the DCW than motor to rotate

The CAM actually adds to the delay introduced by the rotor. On my motorized dish switching between encrypted channels on 19.2E and 23.2E sometimes takes up to 17 seconds. On my other dish, that has a duo LNB at these birds, it is almost always instantaneous (i.e. less than 2 seconds, which is not bad for encrypted HD channels!) This is because with the rotor, the CAM is without signal for some time, which requires it recalculate a DCW, whereas with the Duo LNB the same DCW can be used.

However, to make the choice even more complicated, one must not forget that 2 or more separate LNB's requires a Diseqc switch, which is -most of the time- already incorporated in a duo or triple LNB.

[steddie2.5]

Re: dual lnb

Which pairs of satellites can I get if i go down the twin lnb route?

Re: dual lnb

being inexpensive musnt be the issue. there is an important difference betwen usage of motor and fixed lnbs. when you use two fixed lnbs you will not wait to switch to another satellite. on the other hand if you are using motor you have to wait antil motor rotates the dish right position. if you frequently switch between astra and hotbird or another satellite, it is better to use fixed lnbs rather than motor.

personaly I would prefer two dish .one with several fixed lnbs to watch my favourite satellites and another one with a motor to watch others.

Yes but we talk about few seconds, sometimes a CAM server takes long to send the DCW than motor to rotate

[yselim]

Re: dual lnb

being inexpensive musnt be the issue. there is an important difference betwen usage of motor and fixed lnbs. when you use two fixed lnbs you will not wait to switch to another satellite. on the other hand if you are using motor you have to wait antil motor rotates the dish right position. if you frequently switch between astra and hotbird or another satellite, it is better to use fixed lnbs rather than motor.

personaly I would prefer two dish .one with several fixed lnbs to watch my favourite satellites and another one with a motor to watch others.

Re: dual lnb

it is not suitable to watch two different satellite positions(hotbird 13east-astra 19 east) using twin lnb(one lnb that has two output). if you want to watch these two satellites you must use two seperate single lnbs. look below pic. look at the picture of the antenna. it has more than one lnb holder. you can watch a different satellite for each lnb. you will need two lnbs to watch both astra and hotbird.you must use that kind of equipment to watch both astra and hotbird. twin lnbs or in another meaning dual output single lnbs isnt right answer for you. they are used for different purpose. twin lnbs are used for watching "same" satellite in two different receivers.


another way is to use a motor to watch these two satellite.

And is more inexpencive to use a motor, a motor is cheaper then 4 LNB's for example

[yselim]

Re: dual lnb

what type of lnb should i use ..im located in the uk

it is not suitable to watch two different satellite positions(hotbird 13east-astra 19 east) using twin lnb(one lnb that has two output). if you want to watch these two satellites you must use two seperate single lnbs. look below pic. look at the picture of the antenna. it has more than one lnb holder. you can watch a different satellite for each lnb. you will need two lnbs to watch both astra and hotbird.you must use that kind of equipment to watch both astra and hotbird. twin lnbs or in another meaning dual output single lnbs isnt right answer for you. they are used for different purpose. twin lnbs are used for watching "same" satellite in two different receivers.


another way is to use a motor to watch these two satellite.

Re: dual lnb

A motor is somwhere to 20-30 E, is that not cheap compared to a dreambox that costs up to 500 E ?

[steddie2.5]

Re: dual lnb

just purchased a twin lnb side by side ,,one for astra and one for hotbird..
from a sat shop on ebay ..hope it will be ok

Have u had any luck setting you dish up yet ? If u get it working ok I might give it a go.
I've been looking at motorized dishes on e bay, they're not cheap!

Re: dual lnb

i have same lnb with 2 outputs but this is for 2 diferent resivers to watch same sattelite

Yes but it can also be used on two sattelites if you have a big dish, but like i said with poor results on one of them

[peremacedonia]

Re: dual lnb

Afterall what do you want exactly i tend to think that you wan't to catch one satellite and use two isolated outputs (second variant mentioned by me). If this is the case you need a twin LNB like this one :

i have same lnb with 2 outputs but this is for 2 diferent resivers to watch same sattelite

Re: dual lnb

I never managed to have two satellites on a twin LNB at acceptable signal Level and Quality

[os2222]

Re: dual lnb

in the past i used a twin lnb with two outputs. astra and hotbird. it was always a problem of receiving both sats at the same time if it was raining.
for myself i then bought two single lnb`s with a multifeed holder. thats working really fine
please tell us if you are sucessfull with your configuration of the lnb.

Re: dual lnb

what was the spec on the unit? frequency range etc. this will determine which transponders you can get

The LNB's are universal he will get all the transponders, no metter of specifications

just purchased a twin lnb side by side ,,one for astra and one for hotbird..
from a sat shop on ebay ..hope it will be ok

Ok then it was the first variant, you wanted to catch two sattelites