Inverto Black Ultra & 1.8m Prime Focus Dish?

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nabih said:
In fact it is an old 1.80m dish used in the 1990 s as a collective dish for a building
Since then everyone has his own dish so i got it for nothing
I hope that time has not reduced its performance since

Is it a petalised Jonsa-job? (i.e. is it made of 6 petals of rusting steel with a flimsy feel)
If so your mileage may vary.
But if you could post a picture it would be very helpful.
 

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st1 said:
I think you'll find that this specific question has been answered in post #7. One such thing is Pipino's conversion:

http://www.satellites.co.uk/forums/...verto-twin-black-ultra-flange-convertion.html

But please note this is a destructive process, and may not give the results you are looking for. Probably better off ordering a C120 Inverto off the internet.

Also note that the Black Ultra will most likely work as-is with your dish, you just won't get full signal strength.
The reason is that the F/D factor, which expresses the focal depth and beam width generally is higher on an offset dish (about 0.60-0.65) than a PF one (0.30-0.45).
Which F/D ratio the LNB is made for is determined by the feedhorn design.
The feedhorn inside the Black Ultra generally supports an F/D of about 0.60 (if I remember correctly).

This means that if you point a Black Ultra at a PF dish with an F/D of, say, 0.38, it will only see a smaller part of the reflector surface (probably something like 1/2 to 2/3 of the dish face). In other words it will probably work, but you will not use all of the surface of your reflector.
This can be a serious source of disappointment if you can't see Astra 1N after having obtained a 1.8m dish for the purpose.

This is why you are better off with an LNB with the correct feedhorn than slapping the Black Ultra on it.

Thank you so much sir for your very clear explanation about what i was looking for.
I am convinced now either using a prime focus dish with apropriate lnb and its feedhorn or using a much larger offset dish with a black ultra inverto lnb. There is no middle solution as i see .
Once more thank you so much sir
 

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BM300 said:
Try this option from Inverto

Twin Flange BlackPro LNB 40mm

It works like charm.

twinf-thumb.jpg
Thanks BM300
 

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nabih said:
In fact it is an old 1.80m dish used in the 1990 s as a collective dish for a building
Since then everyone has his own dish so i got it for nothing
I hope that time has not reduced its performance since

A lot of equipment in North Africa at the time would have been for a different frequency. Please post a couple of pictures of the dish (front and rear), so that it can be identified.
 

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Channel Hopper said:
A lot of equipment in North Africa at the time would have been for a different frequency. Please post a couple of pictures of the dish (front and rear), so that it can be identified.

Hello Channel Hopper
The prime focus dish i got is a 6 assembled petals but i think i won t use it since my inverto black ultra will not work with it according to ST1 who gave me a full clear explanation and some technical reasons therefore i let down the project.
I will try to find out an 1.50m offset dish but i am aware it won t be easy in Algeria.
Thank you so much Channel Hopper for your help and best regards.
 

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st1 said:
Is it a petalised Jonsa-job? (i.e. is it made of 6 petals of rusting steel with a flimsy feel)
If so your mileage may vary.
But if you could post a picture it would be very helpful.
Hello st1
I have canceled my project of using a Prime Focus dish for techncal reasons for the moment unless a friend of mine living in FRANCE promise to send me a suitable INVERTO lnb with feedhorn
Thanks for your help.
 

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If it is a Jonsa P1806 ( the 6 stands for 6 sectors) , the f/d ratio is 0.36 .
 
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nabih said:
Thank you so much sir for your very clear explanation about what i was looking for.
I am convinced now either using a prime focus dish with apropriate lnb and its feedhorn or using a much larger offset dish with a black ultra inverto lnb. There is no middle solution as i see .
Once more thank you so much sir

You're very welcome. Glad to be of help.

In my early stages of learning fringe-reception, I myself bought a petalised Jonsa-dish from Maplin Electronics in the UK, and a Invacom single LNB with integrated feedhorn. Not only was the dish a pile of cr*p, but the LNB (as even recommended by Maplin) was made for a an offset dish with a F/D og 0.6, whereas the Jonsa-dish is 0.38.
I never got better readings on the Jonsa from 2D than was obtainable from my 1.2 meter offset SMC dish (visiosat).
Complete waste of money on both dish and LNB.
(Actually, the LNB is quite good, but just not when used with the Jona PF dish.)

I now have a Channel Master type 180 offset dish with a black ultra quad.
Never been happier. (About 1N reception, that is.)
 
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nabih said:
Hello st1
I have canceled my project of using a Prime Focus dish for techncal reasons for the moment unless a friend of mine living in FRANCE promise to send me a suitable INVERTO lnb with feedhorn
Thanks for your help.

Hi there, sorry to hear this. But good luck - you may find that you don't need an Inverto LNB, just some LNB with a feedhorn that will match the dish you have (which may be an IRTE dish, which I'm told is the original dish the Jonsa dishes are copies of. In that case, it might even be good!).
 

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st1 said:
Hi there, sorry to hear this. But good luck - you may find that you don't need an Inverto LNB, just some LNB with a feedhorn that will match the dish you have (which may be an IRTE dish, which I'm told is the original dish the Jonsa dishes are copies of. In that case, it might even be good!).
Good morning st1
The decision is now taken the project to use the 1.80m Prime Focus dish is no longer in my mind
No risks and no possible disapointments waisting time and money
My option is to try to find out a 1.50m Offset dish i ALGERIA or to order it from FRANCE regardless its cost the most important woud be its quality and reception performances.
Best regards.
 

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hi all i had a couple of black ultra lnbs one of which i use,as my dish acts like a prime focus i decided to graft the other to a invacom adjustable feed from ebay,out of the two the grafted one was stronger with an increase of quality,it even brought in weak transponders on nilesat in the daytime,when swapped with the original no signal,so for me its the best thing i had done,it may be different on other dishes.cheers
 

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pride21 said:
hi all i had a couple of black ultra lnbs one of which i use,as my dish acts like a prime focus i decided to graft the other to a invacom adjustable feed from ebay,out of the two the grafted one was stronger with an increase of quality,it even brought in weak transponders on nilesat in the daytime,when swapped with the original no signal,so for me its the best thing i had done,it may be different on other dishes.cheers

Hi Pride ..I already suggested something along these lines right at the start of the thread.
Sadly its difficult for some to grasp the concept of experimentation...as the fear of damage to shop bought gear can be difficult to overcome.
..but as we know ..this is often the way to go as store bought goods are most often a compromise 'one size fits all' ..and _not_ neccessarily the best that can be achieved.
Long live the experimenters and the urge to persue the difficult and almost impossible.
;)
 

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Hello everybody
Can anyone tell me if there is an lnb which works commonly on both offset and prime focus dish sort of standart lnb.
 

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hi VS i agree 100% even the dishes i have owned, had a certain amount of experiment to get a bit more gain out of them.cheers
 

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hi nabih an offset lnb will be a compromise on a prime focus dish,but you should use the right feed on the right dish to get maximum gain.
 

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As Pride says ...the electronics of the lnb are the same ..
What is different is the feed horn ..
In the case of an offset lnb ..this is usually integrated with the electronics ..whereas on a Prime focus this is usually removeable and adjustable ...consisting of a flat plate carrying concentric rings ..
Closer investigation of an offset feed shows it to be trumpet shaped ...basically a reducing cone.
The common point is behind the feed ..ie a tube feed ...which is the same for both types of lnb.
What was suggested is this be severed ..and a concentric ring feed grafted onto a black ultra ..which is known to be a high gain lnb ...but sadly isn't available as is ..for a prime focus dish.
I don't know why this is so ..other than to suggest that most people use offset dishes these days ...and thus a larger market exists..
Once again ..it tends to be that 'money talks'.
rgds
VS
 

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pride21 said:
hi nabih an offset lnb will be a compromise on a prime focus dish,but you should use the right feed on the right dish to get maximum gain.
Hi pride21
thanks
 

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Vipersan said:
As Pride says ...the electronics of the lnb are the same ..
What is different is the feed horn ..
In the case of an offset lnb ..this is usually integrated with the electronics ..whereas on a Prime focus this is usually removeable and adjustable ...consisting of a flat plate carrying concentric rings ..
Closer investigation of an offset feed shows it to be trumpet shaped ...basically a reducing cone.
The common point is behind the feed ..ie a tube feed ...which is the same for both types of lnb.
What was suggested is this be severed ..and a concentric ring feed grafted onto a black ultra ..which is known to be a high gain lnb ...but sadly isn't available as is ..for a prime focus dish.
I don't know why this is so ..other than to suggest that most people use offset dishes these days ...and thus a larger market exists..
Once again ..it tends to be that 'money talks'.
rgds
VS
Hi Vispersan
I am, going to transform my black inverto lnb for my 1.80 PF dish hoping good results for BBC and ITV channels pratically no other choice
If it doesn t work then it will be used as a big solar cooking dish ......... just kidding.
 
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