Adapting an astra/hotbird monoblock to a 100 cm dish

I d like to get a 100 cm dish instead of my present 78 cms which works fine with a 6° monoblock.
How will the 6°spread ,for78 cms,be affected by this larger 100 cms dish?
Which would be an example of multi sat reception adapted to 100 cms?
7w,5w,9E,13E,16E,19E would me my targets.
Also 26E/28E if feasible.
Rotors won t work,too much wind!

The monobloc spread will be narrower on a bigger dish.

Thank you very much,and a happy Easter!
so,instead of 6° for astra/hotbird,how much would it be ?
Lat 43/long 2,33E

rodscha said:

How will the 6°spread ,for78 cms,be affected by this larger 100 cms dish?

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This would be 6 * 78 / 100 = 4.7 degrees, assuming that the opening angle or f/D ratio equivalent of the two dishes are equal.

A bigger dish will have a smaller beam width, which implies that a bigger dish is less forgiving for mismatches in monoblock distances.

A 100cm dish often allows to use separate LNBs, on a multifeed rail. Is that not an option, for you?

Greetz,
A33

yes sure I m considering the idea
May a 4°monoblock work on 13&19?
adjusting for nearness of dish possibly?

Is it not the case that adjustable Monoblocks are now available, with a spread up to 12deg?

Edited to add: Summat like this Adjustable monobloc LNB 3° 4.3° 6.2° 9° Single Cahors

rodscha said:

May a 4°monoblock work on 13&19?
adjusting for nearness of dish possibly?

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4°monoblock, 6°monoblock, that is all relative to the width of the dish, and f/D ratio (equivalent). These latter values are often not mentioned.
A 4°monoblock on a 60cm dish would function as a 6°monoblock on a 40 cm dish (with equal f/D-ratio(equivalent)).
So what kind of 4°monoblock do you mean?
And how would you "adjust" something, on a monoblock? Apart from what Lazarus wrote? (The "spread" can easily be made wider, but hardly smaller...)


The crucial factor of a monoblock is the distance between the phase centers of both feedhorns of the monoblock. Or, the same value: the distance between the center of the two 'tubes' of the monoblock.
That distance must match the angular distance between the two satellites from your location, and the effective focal length of your dish. Accounting for Beam Deviation Factor, of course.

Multifeed skew can be calculated; I've a pretty exact calculator nowadays.

Greetz,
A33

it seems what I need is adjustable LNBc
Moreover the dish is standing near my sitting room,so I can easily fiddle whenever I feel to try some less usual sat,and retune to basic 9//13/16/19
16 not being a priority.

rodscha said:

it seems what I need is adjustable LNBc
Moreover the dish is standing near my sitting room,so I can easily fiddle whenever I feel to try some less usual sat,and retune to basic 9//13/16/19
16 not being a priority.

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Or a second dish.

Makes sense ,I ll still have my 85cms on the side!

a33 said:

Multifeed skew can be calculated; I've a pretty exact calculator nowadays.

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My dish is skewed without any calculator

45°E - 42°E - 39°E - 33°E - 28°E - 24°E

p.s.
my brain is capable enough to imagine how to manage, without 5 years studying at university to be an engineer

rodscha said:

it seems what I need is adjustable LNBc

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Here are the LNBs that you need