Twin LNB performance?

[skype]

DO you guys experience performance difference between twin LNB and single LNB? As to my experience, it feels like twin lnb performs worse than single lnb.

And one other thing I am curious is, are the inputs on twin lnbs fully isolated from each other?

[satman72]

Re: Twin LNB performance?

It is right, twin LNBs works worse then single LNBs.
The two outputs are connected to two differents converters/amplifiers enclosed into same case. The only parts those converters/amplifiers shares are the little dipoles into feedhorn, for horizontal and vertical reception, and of course the mechanical of feedhorn.

[skype]

Re: Twin LNB performance?

Now it really starts to make more sense , why the twin lnbs die easier and operate worse than single lnbs.

[easydigital]

Re: Twin LNB performance?

LNB Gain and Twin LNB performance
The lnb gain tells us how much the incoming signal is amplified before being sent off down the coaxial cable to the receiver. The range of gain specified is between 40dB and 70dB (somewhere between 10,000 and 4,000,000 times the incoming signal power). At first sight, the highest gain you can get would be the obvious thing to look for; however that is not the only criterion when it comes to LNBs.
When you have a large dish looking at high power satellites like Astra 2A and Astra 2B, the gain can be so high that the receiver is overloaded with signals. These can 'swamp' the lower powered Astra 2D satellites signals.

[Fantom]

Re: Twin LNB performance?

You can't get an even defliction of the dish that is why twin LNB's are less effective than single. But if you don't want a motorished dish this is a good option !

[redhezuk]

Re: Twin LNB performance?

It is right, twin LNBs works worse then single LNBs.
The two outputs are connected to two differents converters/amplifiers enclosed into same case. The only parts those converters/amplifiers shares are the little dipoles into feedhorn, for horizontal and vertical reception, and of course the mechanical of feedhorn.

Makes sense and explains why the twin performs worse!

[matrixneo12]

Re: Twin LNB performance?

Can not confirm,I have at home the same performance with single and twin lnb.

[manyax]

Re: Twin LNB performance?

Can not confirm,I have at home the same performance with single and twin lnb.

Are those two LNB's from same manufacturer ? i guess that you sustain that they have the same dB specifications and the single difference is that one of them is twin !?

[matrixneo12]

Re: Twin LNB performance?

Yeah they are from the same manufacturer-specifications are same just the one is twin.

[satman72]

Re: Twin LNB performance?

Makes sense and explains why the twin performs worse!

I wrote it yet, because twin LNB shares same dipoles so the signal received by each dipole is shared by two amplifiers.

[astr1d]

Re: Twin LNB performance?

Is everybody discussing the same thing, here? I seriously think someone (fantom) is mixing up twin LNB and Duo LNBs.

One (duo) has two feedhorns, so you can use one dish to receive two birds.
The other (twin) has two bipoles, so you can receive two transponders from a single bird.

Twin LNBs (for a single bird) will, in principle, be less performant than single LNB's, because the dipoles cannot be both at the optimal position, however the difference should less than 2 dB, so it should be hardly noticable, unless you are trying to get very weak signals. However, you will have a hard time finding a twin LNB and a matching single LNB to perform a test. There are always differences in noise, horn specification and other parameters, even if these LNBs are made by the same manufacturer.

A duo LNB should, again in principle, not necessarily be worse or better than a single LNB, but since pointing is more critical and the dish cannot be used at full gain (cosine of angle between the feedhorns) you will, in real life, always experience less performance.

So, bearing this in mind, I think it is fair to say that, given similar mechanical and electronical specifications, a single LNB will outperform either twin or duo.

@Conax2: Could you provide model numbers of these Echolinks, so we can see if we can find an explanation?

[easydigital]

Re: Twin LNB performance?

Twin LNB performance would never have the Gain of a Single LNB

[easydigital]

Re: Twin LNB performance?

If it's a circular prime focus dish the LNB has to be in front of the centre of the dish and on a standard dish the LNB is placed center in focus for best gain.

that's what I meant conax2

[easydigital]

Re: Twin LNB performance?

I have a circular dish and the LNB is fixed in front of the centre of the dish. I don't know what do you mean by a standard dish??

I have a High quality standard offset 120cm light-gauge aluminum is a highly effective reflector dish with Inverto Black Ultra High-Gain Single LNB works best for me.

[alfred_1]

Re: Twin LNB performance?

I've got a 100 cm Dish with four LNB's. 7°, 13°, 19.2° and 28.5°. I got excellent strengh on all LNB's. What is the max. LNB's for a 100 cm dish? Does someone got experience with more then 4 LNB's? I want 6 or 8 on that Dish.

You can add (if you want) the 9E and the 26E. These two sats have quite a lot of Channels especially the 26E which also has movie channels which are FTA.

I have a circular dish and the LNB is fixed in front of the centre of the dish. I don't know what do you mean by a standard dish??

Circular Dish is meant a perfectly round Dish with a center aligned Lnb, and that is meant a Prime focus Dish.

Now I take it that by standard Dish he meant that the Dish is ''Offset'' which means that the beam comes off the dish at a 22 deg angle upwards. So, with the feed arm at the bottom, if the front face of the dish reflector itself is vertical, the beam elevation angle is 22 deg upwards.