Gibertini OP 125L


Ernst Lobsiger
 

Dear All

Thorsten has a Gibertini OP 125L and maybe others too. I need your help.

I bought a Gibertini OP 125L, drove 300 km to fetch it with my car (they
do not deliver it in Switzerland). The OP 125L came in two packets dish
and antenna mount kit. In the shop I checked that the dish is alu because
Gibertini seems to produce the same dish in steel as well. I also checked
that the mount kit was the right one and complete. Today I wanted to assemble
the mount and found that it had transport damages I overlooked in the shop.
The problem was that the packet had the Gibertini sticker on the bottom
side and the "handle with care" glass and UP arrow was looking down. So
the packet was presented to me upside down and it has been transported that
way. But the damage did certainly not occur on the back seat of my car.
The main damage was a bent plate so that the two square tubes that
hold the LNB would not meet in the right place. I was able to fix every
thing with my mechanical skills. But now I have a real problem:

When I want to introduce the pole clamp between the two plates where
the clamp is fixed with 3 long screws this is only possible with brute
force. Actually the distance between the plates is 1-2mm less than the
width of the clamp. The result is that I can only change elevation
with brute force even when all 3 screws are loose. The clamp is blocked
and then jumps up to 5 degrees. It seems excluded that I can ever use
the fine tune elevation rod. Have I got a friday afternoon specimen?

Owners of OP 125L what is your experience? I think that after loosing
the 3 nuts I should be able to fine tune elevation down to +/- 0.1°.

It almost seems I'll have to drive another 300 km :-(

Ernst


Thorsten Miglus
 

Hi Ernst,

is your pole wide greater then 55 mm? The pole clamp specification says 55 mm - 100 mm.
Mine was not. I fixed this by introducing a second water pipe.
The two parts of the pole clamp should not touch if the clamp is tightened.
Maybe the inner part of the pole clamp is bend up by the outer part when a smaller pole then 55 mm is used?
Is this causing your problem?
Mounting the pole clamp between the two plates needs some force but not brute force.
Adjusting the elevation is no problem.




On Sat, Jul 7, 2018 at 11:33 am, Ernst Lobsiger wrote:

Dear All

Thorsten has a Gibertini OP 125L and maybe others too. I need your help.

I bought a Gibertini OP 125L, drove 300 km to fetch it with my car (they
do not deliver it in Switzerland). The OP 125L came in two packets dish
and antenna mount kit. In the shop I checked that the dish is alu because
Gibertini seems to produce the same dish in steel as well. I also checked
that the mount kit was the right one and complete. Today I wanted to assemble
the mount and found that it had transport damages I overlooked in the shop.
The problem was that the packet had the Gibertini sticker on the bottom
side and the "handle with care" glass and UP arrow was looking down. So
the packet was presented to me upside down and it has been transported that
way. But the damage did certainly not occur on the back seat of my car.
The main damage was a bent plate so that the two square tubes that
hold the LNB would not meet in the right place. I was able to fix every
thing with my mechanical skills. But now I have a real problem:

When I want to introduce the pole clamp between the two plates where
the clamp is fixed with 3 long screws this is only possible with brute
force. Actually the distance between the plates is 1-2mm less than the
width of the clamp. The result is that I can only change elevation
with brute force even when all 3 screws are loose. The clamp is blocked
and then jumps up to 5 degrees. It seems excluded that I can ever use
the fine tune elevation rod. Have I got a friday afternoon specimen?

Owners of OP 125L what is your experience? I think that after loosing
the 3 nuts I should be able to fine tune elevation down to +/- 0.1°.

It almost seems I'll have to drive another 300 km :-(

Ernst


Ernst Lobsiger
 

Thorsten

The pole of my home brew tripod is 60 mm but I noticed an optimum
pole would be 75 to 80 mm. The image I attached is taken from the
internet just to show the layout. My mount is still on the table
and the dish not attached. So nothing can be bent. By inner (and
massive) part of the clamp you probably mean the problem half that
is not seen on our pictures. It's the part that will end between
pole and dish. This part takes the 3 long horizontal bolts that
end with the nuts visible at right. Moving elevation turns around
the center bolt. This part of the clamp is just too wide for the
plates it fits between. The plates are part of the big steel
pressed form piece. From the construction the gap cannot easily
be widened even by 1 mm. Thats why already intoducing the inner
clamp was a real pain. Greasing with a WD40 spray did not help.
No chance to fine tune with the elevation rod on the bottom.
The friction forces are just too high even with loose bolts.

Ernst


Thorsten Miglus
 

Ernst,

it is more then one year ago when I mounted my dish. I can not remeber all the details.
But yes, I had the same problem as you.
Force was needed to locate the dish mout over the pole clamp.
I think this is intended to make the dish mount very stable.
Be aware that the fine tune elevation rod can only be used in the range of +/- 1 degree.
In the first step loose the two nuts on the fine tune rod.
When the dish is completely assembled you can grab the dish with your two hands on the upper an lower end.
Then turn it up and down to roughly tune the elevation until you can receive Eutelsat 10A.
Afterwards use the fine tune rod to optimise the elevation for best SNR.

Cheers,
Thorsten



On Sat, Jul 7, 2018 at 10:46 pm, Ernst Lobsiger wrote:

Thorsten

The pole of my home brew tripod is 60 mm but I noticed an optimum
pole would be 75 to 80 mm. The image I attached is taken from the
internet just to show the layout. My mount is still on the table
and the dish not attached. So nothing can be bent. By inner (and
massive) part of the clamp you probably mean the problem half that
is not seen on our pictures. It's the part that will end between
pole and dish. This part takes the 3 long horizontal bolts that
end with the nuts visible at right. Moving elevation turns around
the center bolt. This part of the clamp is just too wide for the
plates it fits between. The plates are part of the big steel
pressed form piece. From the construction the gap cannot easily
be widened even by 1 mm. Thats why already intoducing the inner
clamp was a real pain. Greasing with a WD40 spray did not help.
No chance to fine tune with the elevation rod on the bottom.
The friction forces are just too high even with loose bolts.

Ernst


diogenes1@...
 

Since the Gibertini dishes have become a topic can I ask a rather fundamental  question ? Is it more difficult to align a dish the larger it is? I ask this because I install a 1.5m Gibertini dish a year ago but I have never been able to align it with a satellite.
Regards,
Peter


Thorsten Miglus
 

Peter,

the answer is yes. The larger a dish the smaller his beam width.

Cheers
Thorsten


On Sun, Jul 8, 2018 at 05:24 am, <diogenes@...> wrote:
Since the Gibertini dishes have become a topic can I ask a rather fundamental  question ? Is it more difficult to align a dish the larger it is? I ask this because I install a 1.5m Gibertini dish a year ago but I have never been able to align it with a satellite.
Regards,
Peter


Ernst Lobsiger
 

Peter

Yes this is really fundamental physics: For a given frequency the bigger the antenna size the smaller the beam width and the harder to point the beam to the sat. Your Gibertini OP 150s has a half power beam width of 1.1°. You should manage to point it 0.5° from the SAT to get a signal  and then fine tune it to within 0,2°.

The TRIAX dishes I used up to now are known for very bad elevation adjustment possibilities. That's why I always added my special elevation rod that has been simplified and improoved for home brewing by Arne van Belle. From the construction the Gibertini OP 125L (also the OP 150s) comes with a good looking elevation rod out of the box. But it seems manufacturing precision of the OP 125L antenna mount is not what I expected. All antennas then have an azimuth pointing problem as long as they use the traditional pole clamps. And the pole diameter for a Gibertini OP 150s should definitely be 80mm (high wind loads) .

Ernst


Ernst Lobsiger
 

Thorsten

I drove another 300km to get a second antenna mount for my Gibertini OP 125L.
And guess what: I have exactly the same mechanical problem with the elevation
setup. No use to deal with these people from the online shop that import the
OP 125L via Germany (!). Today I mounted the dish on my modified tripod. I Q&D
pointed the antenna via landmarks and elevation indication only. I started with
EsNo = 14.2dB on T1 which is +2dB from my best results with the old TRIAX TD88.

During the next days I'll try to fine tune my dish. If the elevation adjustment
problem I expect from my experiments with the bare mount on a working table
persists I'll eventually contact Gibertini in Italy directly. Stay tuned.

Ernst


Thorsten Miglus
 

Ernst,

I feel sorry that you have so much trouble with the dish.
But I am happy that you are up and running now.
Actually my TP1 SNR is up to 15.4 dB during chilly night hours.
Fine tuning is a challenge. I was sure to have the optimum.
But sun - sat - collinearty told me that I was 0.4 degrees west.
Tightening the eastwards screws of the pole mount a little to turn the dish a tininess east gave me +0.3 dB SNR.

Thorsten


On Mon, Jul 30, 2018 at 09:07 PM, Ernst Lobsiger wrote:

Thorsten

I drove another 300km to get a second antenna mount for my Gibertini OP 125L.
And guess what: I have exactly the same mechanical problem with the elevation
setup. No use to deal with these people from the online shop that import the
OP 125L via Germany (!). Today I mounted the dish on my modified tripod. I Q&D
pointed the antenna via landmarks and elevation indication only. I started with
EsNo = 14.2dB on T1 which is +2dB from my best results with the old TRIAX TD88.

During the next days I'll try to fine tune my dish. If the elevation adjustment
problem I expect from my experiments with the bare mount on a working table
persists I'll eventually contact Gibertini in Italy directly. Stay tuned.

Ernst


geojohnt@...
 

Hello Ernst,

Sorry to hear about your problems - and more so that you are having them with a Gibertini dish.

I am hoping to upgrade my system this autumn and would have gone for a 1.25 m Gibertini dish instead of my 1 m dish 'standard dish.'

Somehow, Gibertinin dishes have the reputation of having the highest gain of 'same size dishes.'

I wonder if you could please send a photo of the dish/az/el pole fixing arrangement to my personal email address?

The 1 m (I think) Gibertini dish that EUMETSAT used for their EUMETCast Conference some years ago had a simple but robust looking mounting arrangement.

Best wishes,
John.

+++++++++++++++++++++

In a message dated 30/07/2018 20:07:24 GMT Standard Time, ernst.lobsiger@... writes:

I drove another 300km to get a second antenna mount for my Gibertini OP 125L.
And guess what: I have exactly the same mechanical problem with the elevation
setup. No use to deal with these people from the online shop that import the
OP 125L via Germany (!). Today I mounted the dish on my modified tripod. I Q&D
pointed the antenna via landmarks and elevation indication only. I started with
EsNo = 14.2dB on T1 which is +2dB from my best results with the old TRIAX TD88.

During the next days I'll try to fine tune my dish. If the elevation adjustment
problem I expect from my experiments with the bare mount on a working table
persists I'll eventually contact Gibertini in Italy directly. Stay tuned.


Ernst Lobsiger
 

John,

The photo is attached to my first post of this topic :-). Bear in mind that the pole must be 55mm in diameter (minimum) but should rather be 75mm (optimum for the clamp and high wind loads). The antenna must be attached on top of the pole. If you mount it in front of a longer pole you will be very limited in elevation.

I have not yet fine tuned my OP 125L antenna. Far too hot for antenna pointing experiments these days ...

Regards,
Ernst


Mads Kristoffersen
 

Hi Ernst

Can you post a image of your special elevation rod?

My system is out of business for the moment but maybe I have a chance putting it into service and I would love to have a better elevation-option on my Triax (TD-110).

Regards
Mads


Ernst Lobsiger
 

Mads,

Below my Triax TD 110 elevation rod. You can turn it with a
screw driver from below. Inside the clamp is a hard PVC block
with two slightly displaced perpendicular drillings. One takes
the horizontal center bolt and the vertical drilling is threaded
for the elevation rod. Arne made a version that is easier to homebrew
with things you get in any hardware store. Instead of my PVC block
he simply took a scew nut and a window hinge. He had an article
somewhere (GEO ?) but I don't remember a link. Here are his pictures:

http://home.hccnet.nl/a.van.belle/GEO/TriaxElevationAdjustment1.jpg

http://home.hccnet.nl/a.van.belle/GEO/TriaxElevationAdjustment2.jpg

http://home.hccnet.nl/a.van.belle/GEO/TriaxElevationAdjustment3.jpg

Sorry Arne for the deep links :-) but Google knows them anyway ...


Cheers,
Ernst


Mads Kristoffersen
 

Perfect, thanks :)

Regards
Mads