Evaluation of Invacom's QPF-31 LNB for use in Nilesat's fringe areas..

[canofan]

There are LNB's, on the american market, specialised in the linear single band 11700 to 12200 mHz. Doing something special in this band is an american particularity as they use this band for fss.
Invacom is putting on the american market a special LNB to serve this application but at the same time serve the circular band from 12200 to 12750 mHz. Invacom's QPF-31 is a quad LNB having two high band linear and two high band circular outputs. The linears are volt switching V/H and the circulars are volt switching left/right.
In its specification, there are two linear polarisation input frequency bands in the FSS band: 11.7 to 12.2 gHz and 12.2 to 12.7 gHz; and one circular input frequency band 12.2 to 12.7 gHz.
The linears are available on ports 1 and 3 while the circulars on 2 and 4.
It is not clear to me, how to appreciate the peaking effect, which will enhance the gain. And how the appropriate linear band is selected from the receiver's end.

 

[canofan]

Leaving the circular options aside for those who need them.
The possibilities of this LNB for Nilesat, in the linear positions seem, up to now, incredible.
Ports 1 and 3 go into a disecq switch to the receiver and provide higher gains in both bands 11.7 to 12.2 and 12.2 to 12.7.
With a Channel Master using a 6060-07 feedhorn, using this lnb configuration would be equivalent to upgrading from a 1.2M to a 1.4M or from a 1.4M to a 1.8M.
And as rd100 indicated in another post using a 6060-10 would make further improvement in the 11.7M to 12.2M band. Though in this case the 12.2M to 12.7M will not be used.

 

[Channel Hopper]

This LNB will be of no use to you if using on Nilesat, (or anywhere in Europe)

 

[canofan]

This is an axiomatic statement. It does not let me understand.
I needed to use only the 2 linear ports of this LNB. These ports present peak gains in different bands.
Adding them through a switch would allow higher gains than a single "normal" LNB.

 

[Channel Hopper]

You are combining the outputs, not the valuable incoming signals

But if you don't believe me, try it and see.

 

[Rd100]

Just use a 6060-07 with a invacom lnb if you do not get any signal get a bigger dish.

 

[Llew]

It's true that narrowing the range of frequencies to be amplified will allow increased gain - gain versus bandwidth - (not noise factor, which is limited by the amplifier's device characteristics), which after all is why the LNB's bands are 'split' into two (high and low).

However, the quoted gain and NF appear to be the same as their 'normal' models e.g. QDF-031, so I don't see what advantages there would be.

Llew

 

[canofan]

Just use a 6060-07 with a invacom lnb if you do not get any signal get a bigger dish.

I cannot set a bigger dish on the 13th floor of the building. Wind and the impossibility to make better anchoring than I already have. May be a second dish. Anyway my dishes will not be motorised.
I already have an Invacom QDF-31 so when I get the feedhorns I will surely try it.
But I am trying to build on an idea of yours: Norsat 4206A plus a 6060-10 to get higher gain.
The QPF-31 seemed worth considering for its 0.3db noise and its LOF of 10.75. One could use a 6060-10 which makes it is even a better choice than the "Norsat 4206A x 6060-10" combination.
Besides, The QPF-31 offers a further completely independent circuit with an LOF of 11.25. This other circuit has the potential of improving the reception of the following transponders: 12207V, 12226H, 12284Vand 12303H, and also the tp's in the high band of Atlantic Bird 4, going up to 12399H.
But if I decide to use this higher band second output I would have to forgo the 6060-10 for the wider band therefore less efficient 6060-07.
There is also a normal 40mm version of the new generation QPF: the QPH.
Since this whole LNB is designed to work in the high band, may be the use of CM feedhorn improves only marginally on the standard version.

@Channel Hopper

You are combining the outputs, not the valuable incoming signals
But if you don't believe me, try it and see.

It is not a question of not believing you.
I only want us to be talking about the same thing.
PLease remember that the 2 linear outputs are different LNB's altogether in the same package, having each their own oscillator. I am not trying to combine the outputs of the 2 LNB's. I would be switching from one to the other as needed; both outputs being fed to a 2 way committed switch, which in turn will be connected to the receiver through my 8x1 diseqc 1.1 non committed switch.

 

[canofan]

Hi Llew!
I am quoting RD100 from another thread

Right here it goes the circular option is for satellites the use left & right hand circular

Also you are wrong with the requirements you only need a dual linear / circular orthogonal for VSAT ( 2 way satellite Internet) as you need two ports one port for the c120 lnb and one for the BUC (transmitter)

And just to add the best way to get the most amount of gain out of your dish for nilesat is as follows, At home a have a 1.8m dish and get nilesat 24/7 and in the rain,

I also can receive nilesat on my 1.2m Andrew type 120 dish but the signal drops out in the rain this is with the 611-6060-07 linear feed and invacom but it does not drop out in the rain using a 611-6060-10 and a professional norsat 4000a lnb which covers 11.7 -12.2 and gives a better gain all around as the lnb covers the right band for the showtime transponders and the feedhorn 611-6060-10 gives better gain as it covers a narrower band of the ku-band

As RD100 is getting such good results with the CM120 and 6060-10 plus NORSAT 4206A, I thought it worthwhile to explore further in this direction.

 

[Llew]

Well, he is using an expensive professional LNB!

Always worth experimenting though canofan, but I'd like to see the Gain/NF printout of the Invacom to see the spread over the bands concerned for comparison.

 

[Channel Hopper]

@Channel Hopper
PLease remember that the 2 linear outputs are different LNB's altogether in the same package, having each their own oscillator. I am not trying to combine the outputs of the 2 LNB's. I would be switching from one to the other as needed; both outputs being fed to a 2 way committed switch, which in turn will be connected to the receiver through my 8x1 diseqc 1.1 non committed switch.

Unless I am mistaken, the QPF/H 31 series LNB is a switchable four port LNB, not a fixed polarity/frequency output unit ?
Regardless, the 2 linear outputs are the same LNB in the same package, even the oscillator used is the same. The only difference is the outputs are further directed into a switching matrix within the housing.

What you are attempting is limiting the frequency input to the LNB by use of the Invacoms tuned mechanical port - which will increase the incoming SNR by a fraction, but you losing any potential improvement to your reception by the combination of the mechanical port having a depolariser inside, which introduces a 3dB loss before you begin to add up the link budget.

Adding the port outputs makes no difference to the above, and will introduce further noise from the switching matrix, plus the additional connections within the cabling , which could detract from the overall SNR, which is not what you need.

All the best receive systems use dedicated single components at the head end, any switching system at this end is a compromise of cost against signal and multiple connection to other equipment.

 

[canofan]

Each output operates independently from the other three making it possible to connect up to four different receivers to this one LNBF with each receiver operating independently from the others.

 

[Channel Hopper]

Each output operates independently from the other three making it possible to connect up to four different receivers to this one LNBF with each receiver operating independently from the others.

So my last post was correct then.

Try it, and find out.

 

[canofan]

Yes you are correct.
The QPF does not bring the solution.
I shall not pursue therefore on this thread.
I shall pursue my quest on:
http://www.satellites.co.uk/satelli...108196-using-c120-feedhorn-channelmaster.html