andrews feed horn big dissapointment

Channel Hopper

Channel Hopper

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Venton twin is also a good lnb William

Which has nothing to do with feedhorn / LNB matching.

Tread carefully.
 
RimaNTSS

RimaNTSS

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The focal point from my Fibo 120 is +- 74 cm from the middle of the dish but satlex have other values .
Why do you think the LNB should be pointed at the middle of the dish? And what is an offset angle of the main mirror of Fibo 120?
 
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Channel Hopper

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The LNB feed looks way above the true focal point, regarless of the dish type. Possibly compensating for incorrect elevation.
 
RimaNTSS

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The LNB feed looks way above the true focal point
This feedarm belongs to dual-reflector antenna, so true focal point of the main mirror located approximately where I draw red circle IMG_20190528_144913 (Large).jpg . The green circle represents location of the second focal point.
@Phoenixx if you have more plans to experiment with your fibo dish, you can borrow this holder from me.
 

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Channel Hopper

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This feedarm belongs to dual-reflector antenna, so true focal point of the main mirror located approximately where I draw red circle View attachment 124722 . The green circle represents location of the second focal point.
Understood, though the measurement on the image (160+mm) is still more than I remember to the top of where the Gregorian feed is supposed to be. From memory ( and the last time I worked with a Fibo was some ten years ago) the green dot - on a 90cm reflector - was under 100mm from the top of the boom arm.
 
Channel Hopper

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RimaNTSS

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Aha, 92mm. :Y
This "Aha" is not always the case :confused , it is just for some Fibo 90s, and approximately. For me that more seems ~95mm. When we speak about Fibo 120 than distance is about 112mm. All Fibo feedhorns are same, but plastic pice which goes between the feedhorn and the feedarm differs between antenna models. There are slight difference between shapes of subs for different antenna models. Feedarms are also happened to be in different length, even for 90cm antennas.
Ones friend of mine bought Fibo90 with broken feedhorn, but he was eager to get it working. So, he borrowed feedhorn from me and gave the broken one together with good one to his father. Father worked couple of days and made the replica. I liked the replica so much that I gave away normal feedhorn and took the replica IMG_20190528_183408 (Large).jpgIMG_20190528_183513 (Large).jpg .
 

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Phoenixx

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The offset from the fibo 120 is 27,3 ^ so i set the dish 30-27.3 = 2.7 ^ almost vertical for Astra 4a

Today i have follow you advise Rima and i check the dish, and indeed it`s warped for 1 cm ,i have pull the aluminnium
a little and now it`s almost perfect match between the wires from the dish. The focal zone from lnb is smaller, must be good now.

Earlier i read a threat from another forum about focal point from Trust and i understand that the lnb must look to the middle from the dish
hope, i am right..

First i have testing with the ibu lnb and mbc is also at the day visable now, signal is better. Later i go testing with Prodelin feedhorn and mod lnb.
 

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RimaNTSS

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the lnb must look to the middle from the dish hope, i am right..
Not really. LNB should be pointed below the center of the dish. In case od Deltastar 120 (Fibo120) the aiming point (Le point "G") is 863mm from the top of the mirror (distance A-G) CMHolderPlacement.jpg diagram is for CM dishes, but principle is the same.
27.3* offset angle is correct.
Your dish become warped over the years of use, that is part of life. Nothing and nobody is perfect. And I am pretty sure, after you fixed the shape, it will become warped back sooner or later (maybe faster than you hope). This issue can be fixed only in radical way.... change the main mirror to another one, for example Channel Master 1.2m or other sturdy shape antenna, which is made of plastic.
 
RimaNTSS

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Another way how to experiment with Fibo dish is to install standard LNBF like OBU instead of original Fibo feedhorn. This is not a bad option to do, I've tried it and results were promising. Of course there is a need to make some kind of LNB holder which fits on original Fibo feedarm. Example of such a holder on the pictures. If clamp is changed to 63.5mm then C-band is also possible.
 

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Channel Hopper

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I have looked everywhere but cannot find a schematic / technical drawing for the Fibo 1.2. Was it also badged as a Philips at some point ?
 
scopus

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moonbase

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I have looked everywhere but cannot find a schematic / technical drawing for the Fibo 1.2. Was it also badged as a Philips at some point ?

I recall seing a Fibo style dish with a Grundig logo on it on the wall above the shop outside of the old Spectrum satellite/TV premises in Selsdon.
 
RimaNTSS

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I think majority of Fibo 120 came under the name "Deltastar"
 
nelson_b

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I recall seing a Fibo style dish with a Grundig logo on it on the wall above the shop outside of the old Spectrum satellite/TV premises in Selsdon.
Yes - The one i have has the Grundig logo grundig fibo.jpg
 
william-1

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Channel Hopper

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Not even here (which I had forgotten) :-doh

 
Channel Hopper

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I suppose I could just divide all dimensions of the Fibo 90 by 0.75....... :-wow
 
william-1

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OP Gibertini 100 XP+ Inverto Black Ultra 0.2
Superior Dark Motor (160° max)
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TM6902HD (A/B switch) Amiko A4K

Raven 88cm Mesh Dish +TM-0.1
Stab100 H to H (120° max)
(53 east to 45 west)
Octagon SX88+ (A/B switch), TM5302HD

45cm dish SpiderboxHD9000 28E
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