New gregorian dish, fibo. missing funnel... how to mount universal lnb?

[MarsBar]

It appeared the LNB was 4mm from the center line of the beam, vertically to the side. I assume this caused the 2 percent drop in signal. My conclusion is that if the lnb position is fine tuned it will match the original performance.

 

[MarsBar]

It looks like my FIBO project will be delayed, as a pillar of concrete has to be made in order to install it. Not sure if I need it anymore though...

Branches from a tree must have blocked my BBC signals, and after trimming the tree I get the following result:

Dish: 85cm offset TRIAX
Goto X motor
Bracket: Home made 1m aluminum pipe
LNB Black Ultra Single HGLN 40mm LNB Item Nr.3116
Signal in good weather BBC HD: Signal intensity 91%. Signal Quality 62%.

In general rain, the signal quality drops to approx. 44%, but picture is still OK.

Insane heavy rain: Some noise starts to show up in the picture (very rare)

I also managed to get the GoToX function working. I am going to do a write-up of my current Receiver in another section.

Below is a picture of my current setup that now works well.

Thanks!

 

[samoloko]

how does your lnb holder compare to original - did you receive better level

Interesting topic and nice antenna!
If you can not make it perfect make it adjustable. That is one holder I've made couple of days ago. View attachment 132193View attachment 132194 You, of course, can come with another solution out of aluminum, plastic or even wood.
If you do not have original Fibo feedhorn I would suggest to:
- remove the SUB and install universal LNB in antenna's focal point and aim LNB to antenna's G-spot;
- catch your due-south satellite to get maximum signal;
- without moving the dish, remove the LNB and install the SUB.
- install LNB in the SUB's secondary focal point to get maximum signal;
- enjoy perfectly tuned Gregorian type antenna and perfect reception performance.

It is too late ATM. I will come back tomorrow with data about antenna's offset angle, location of focal point and LNB's aiming point.

@MarsBar on the attached picture you can see some data of your antenna. I used picture of Fibo55, but data is about Fibo90. Focal point if the main reflector is located somewhere in the red circle. So, for the first step you need to place universal LNB in such a way that it's phase center co-located with antenna's focal point. Offset angle of Fibo 90 is 24,6*. When you point your antenna to due-south satellite you can measure leaning of the reflector and from data you get it is possible to find out whether you have LNB in the right position.

 

[RimaNTSS]

how does your lnb holder compare to original - did you receive better level

Alex! LNB-holder can improve the reception only if manufacturer made some mistakes in design of the original one. But there are no mistakes in Fibo antennas designs, as far as I know. So, the LNB-holder I made was just to allow installing a simple LNB when the original Fibo feedhorn is removed. I did not make special comparison tests between original feedhorn plus LNB versus only LNB (like IBU), but, I think the reception results will be more or less same.

 

[drusattv]

It looks like both dishes are 90x100cm.

Here are the measurements:

Distance: 81mm

Height from beam top to center lnb: 102mm

LNB approx 3 deg backwards.

Current offset dish: 95x85cm

New dish, dub reflector: 90x100.

Hi
Is sub reflector 30cm ? (Length and width)؟

What is the depth of th sub reflector ?

Best regards

 

[RimaNTSS]

Is sub reflector 30cm ? (Length and width)

No, it's working area approximately 240x245mm. Please do not tell you wish to fabricate one! If you do then keep in mind the SUB must have 2 focal points.

 

[Channel Hopper]

No, it's working area approximately 240x245mm. Please do not tell you wish to fabricate one! If you do then keep in mind the SUB must have 2 focal points.

You don't have to be so pessimistic.

dish behind the window

I drove past the old SPECTRUM shop in Selsdon yesterday. It is now a Kitchen and Bathroom appliances shop but the old Grundig 1.2m Gregorian dish dish from the SPECTRUM days still seemed to be on the wall. I did not get the chance to get a good look at it as the shop is on the corner of a...

www.satellites.co.uk

If members wish to check how close it is to the subreflector of many commercial antennas, the dimensions of the particular wok mentioned are 326mm (diameter/chord, before bending -deliberately in vice or by dropping) and 97mm depth/height.