Monobloc LNB help please

[eatjunk]

Hi everybody, hopefully a quick question.

I had heard that monobloc LNB's were designed for 80cm dishes. Does this mean that they cannot be fitted to other dish sizes (smaller or bigger), and if not, why not?

I understand if the dish is smaller you may not receive enough signal, but if we assumed that signal strength is not an issue. Also, I am not talking about Sky dishes which I know use a different LNB holder.

Please can somebody advise here. Thank you.

 

[RimaNTSS]

I suppose, there are different monoblocs available on the market. Dou you already have one on hands? If not, than you better avoid getting one. For several reasons it is better to use 2 separate LNBs instead of monobloc IMHO.

 

[Robinson74]

eatjunk, the reason is quite simple. You have a fixed distance between the 2 parts of a monobloc LNB so they only fit certain dish sizes and certain satellite configurations. If you have 2 separate LNB's you can select the distance yourself, adjusting it for dish size and your satellite configuration.

 

[Lazarus]

Adjustable Monoblocks are now available for spacings up to 12 deg (Possibly more - not bang up to date with the very latest offerings)

 

[timo_w2s]

Indeed, as the dish gets bigger the spacing of the LNBs will get wider for the same two satellites. So a fixed monoblock for an 80cm dish has the two feedhorns spaced for an 80cm dish. If you then put it on a 60cm dish you are going to have to compromise one or a bit of both satellites as you can't get both feedhorns in the centres of the two incoming signal paths. The signals from the two satellites may be high enough to overcome the loss in signal by the misalignment of the feedhorns but it's not ideal as an adjustable monoblock or two separate LNBs allowing you to fine tune each LNB individually.

 

[rolfw]

For 6 degree spacing on a 60cm dish, you can use a 4.5 degree monobloc, will be pretty much perfect. I tend to use the little Triax TD54 or 64 with two black Ultra LNBs on their little 2 LNB flexiblock.