Multiple lnb in Prime Focus 2.40

hatters1976

hatters1976

Member
My Satellite Setup
Stable Dish 2.40m (7w, 0.8w, 1.9e, 3e, 7e, 13e, 16e, 19e)
Gilbertini 1m (36e, 39e, 42e, 46e, 52e)
E-space 1.20m (9e)
Octagon sf8008, Edision os mio +4k, Gt Media GT Combo.
My Location
GR
I have currently eutelsat 7e at the center of the dish i wonder if it is possible to have signal
in hellas sat 39e. At the moment my extension i have put is 10e,13e,16e and it still has space
i wonder if i add second or third extension hellas sat would come? Opinions ... Unfortunately
my 1.80 spare dish where i had hellas sat has serious damage after the storm.
 
What dish type ?

Profile says 'parabolic, so not much to go on apart that it's not non-parabolic.
 
prime focus 2.40 20-25 years old i just wonder if it can be done ... i have not tried it
 
Channel Hopper said:
Pictures ?
Click to expand...
What would pictures have to do with his question?
And he mentioned his dish type in the title.

So, what are your reasons for your questions? I don't see that they would have any relevance to OP's question.

Gr,
A33
 
a33 said:
What would pictures have to do with his question?
And he mentioned his dish type in the title.

So, what are your reasons for your questions? I don't see that they would have any relevance to OP's question.

Gr,
A33
Click to expand...

I may have missed where the o/p provided the make and model of the dish, however an axisymmetrical reflector would have limitations on the ability to achieve acceptable reception away from the sole focal point. A dish with a deeper parabola (lower f/d) will be more restrictive with satellites further away from the one to which it is aligned.

I have detail in the office that identifies the half-power beamwidths of a range of 1.8. 2.4 and 3m reflectors, which might help determine just how far away useful signal can be received from the boresight. Any values are subject to the usual margins of dish quality. reflector/feed efficiency and downlink frequency.
 
Channel Hopper said:
... however an axisymmetrical reflector would have limitations on the ability to achieve acceptable reception away from the sole focal point. A dish with a deeper parabola (lower f/d) will be more restrictive with satellites further away from the one to which it is aligned.
Click to expand...

Well, of course with a prime focus (axisymmetrical) dish the multifeed LNBs would be in the signal path, and assuming an f/D of about 0.4 the LNB would need to have a matching illumination angle, if possible.
And indeed, it might be that a lower f/D antenna has more mirroring abberations than a higher f/D antenna, for the off-axis LNBs, I never saw figures about that effect though.
But I still don't see that knowing the exact type of PF dish and seeing pictures would really affect the answers to OP's question.

Channel Hopper said:
... the half-power beamwidths of a range of 1.8. 2.4 and 3m reflectors, which might help determine just how far away useful signal can be received from the boresight.
Click to expand...

The HPBW would not affect multifeed possibilities, unless of course you are dealing with a very small dish (say smaller than 50 cm or so).
You are not wanting to receive the 39E satellite with the (center) 7E LNB, do you? That's where the HPBW would come in.


hatters1976 said:
i wonder if i add second or third extension hellas sat would come?
Click to expand...
I'm afraid I have no answer to that. You want to keep 7E central, or is placing 16E (or 19E) central also an option?


Greetz,
A33
 
a33 said:
Well, of course with a prime focus (axisymmetrical) dish the multifeed LNBs would be in the signal path, and assuming an f/D of about 0.4 the LNB would need to have a matching illumination angle, if possible.
And indeed, it might be that a lower f/D antenna has more mirroring abberations than a higher f/D antenna, for the off-axis LNBs, I never saw figures about that effect though.
But I still don't see that knowing the exact type of PF dish and seeing pictures would really affect the answers to OP's question.



The HPBW would not affect multifeed possibilities, unless of course you are dealing with a very small dish (say smaller than 50 cm or so).
You are not wanting to receive the 39E satellite with the (center) 7E LNB, do you? That's where the HPBW would come in.



I'm afraid I have no answer to that. You want to keep 7E central, or is placing 16E (or 19E) central also an option?


Greetz,
A33
Click to expand...
On a 2.4m reflector the shadow of even three or four Ku feed/LNBs would be negligible.

Seeing the dish in question (has the make /model been confirmed ?) would provide initial f/d ratio and feed match, as well as the condition of a 20-25 year old design.
 
Thanks for your answer i decided eventually to do it seperately with another new dish size 1.20
I think it is the best option.
 
Having a so large dish, why not thinking to a motorised option? You would get more satellites with very strong signal, including the 39E obviously.
 
I decided just to add a new 1.20 dish for hellas sat it was the cheap option with 70 euro.
I will have now to get rid of the roof the badly damaged 1.80 old dish. Reception on it
fall at least 30% after the dish damaged all over it.
 
@hatters1976 photos will always help and can help others members :)

39e is very powerful in Mediterranean countries, 60cm or 80cm dish well aligned is more than enough just for this sat!
The best solution for me, will be 80 cm dish and H/H diseqc motor .
I've made this setup for my dad in central France, cheap and easy to install just align to your due south satellite and the motor do the job for others satellites ( 55e to 47.5w ).
52e 42e 39e 28.2e 23.5e 19.2 16e 13e 9e 7e 4.8e etc ... are easily locked from that place.

20250926_151725.webp
 
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