LNBF v FEEDHORN

[koansrc]

Is it easy to explain the difference between using an LNBF and an lnb with a seperate feedhorn ? What sort of improvement could I expect if I swapped my maximum 0.2 LNBf for one of those LNBs with a seperate feedhorn (not supplied with the 1.5m noname dish)?

( at present I find that if i slide the lnb even slightly back away from the dish 0.5cm the signal drops off dramatically )

 

[Llew]

Using a feedhorn tailored to my SMW dish with an Invacom 0.3db C120 LNB gave me significant improvement compared to using the same specification Invacom LNBF.

It will obviously help if the feedhorn matches your dish.


Llew

 

[koansrc]

How do I match the feedhorn to the dish ? or how do I choose a feedhorn ? and is the feedhorn then not protected from the elements ?

 

[Llew]

Have a look here -

_www.satellitesuperstore.com/feedhorn.htm

for info on feedhorns for various offset dishes (not promoting their products, just an example).

The feedhorn has a protective cover. When bolted onto your LNB it will be sealed with an 'o' ring to protect the LNB against the elements.

Llew

 

[koansrc]

Cheers Llew! I guess this is all pretty basic stuff. I'm still not sure what you mean by "tailored to my dish". Does that mean it was supplied by the dish manufacturer ?
What if the dish wasn't supplied with a feedhorn ? How would you choose one ?
Also , does "adjustable" mean the feedhorn can slide closer/further from the dish ?

 

[Llew]

There's some discussion on this topic in various threads on the forum.

Search for feedhorn+adjustable.

Or check http://www.satellites.co.uk/satellite/sky-digital-uk-platform-astra-28-2e-fringe-reception-tech/89655-feedhorn-types.html

Llew

 

[koansrc]

There's some discussion on this topic in various threads on the forum.

Search for feedhorn+adjustable.

Or check http://www.satellites.co.uk/satellite/sky-digital-uk-platform-astra-28-2e-fringe-reception-tech/89655-feedhorn-types.html

Llew

Thanks there does seem to be some information in the threads. I'm narrowing it down to an inverto c120 and a feedhorn (Inverto doesn't seem to supply them). BUT I'm still wondering what it is that makes the difference between an LNBF and an LNB and feedhorn. I get it if the feedhorn is supplied with the dish, but what's the difference if it's not supplied with the dish ? is it because it's adjustable ? is it just a better construction ?

 

[Llew]

With some makes of large dishes, an LNBF may not be illuminated correctly as it's a 'one size fits all' compromise. This can be critical when on the fringe of a signal. An adjustable feedhorn may well help, but it's still possible it may not be a perfect solution unless it's ideally matched to your dish.

Further, I can't advise - there are several members here who have far more experience in matching LNB's to dishes, as those threads mentioned show.

Llew

 

[tesla]

The professional LNBs (for demanding reception) are made without a feedhorn attached to them.

The professional LNBs may receive a single band or a single polarization.