Usals problem & alignment

[Trust]

Here's two photos of the holder. If I can dig out the dish, I'll try and photograph the arm tomorrow..

View attachment 130466View attachment 130467

On this pictures the clamp is attached the otherway arround , the backside of the lnb is pointed to the dish (just to make things clear to RedAlert)

 

[sonnetpete]

I did mention that in post #256

 

[Trust]

I did mention that in post #256

Sorry , I missed that .

 

[Red alert]

This photo taken with head height at lnb shows it pointing higher than the middle bolts of the dish. Shouldnt this be resulting in lower signal than a high one. But at this position im picking up higher signal across many sats. How is this so? @a33



@sonnetpete when i push the lnb forward so the back hits the holder then signal becomes 0%

 

[sonnetpete]

when i push the lnb forward so the back hits the holder then signal becomes 0%

In my experience, moving the LNB from fully forward to fully back usually varies the signal quality by about 15% to 20%. What is the quality level prior to moving the LNB? I agree, the LNB alignment does look odd in the photo but is this due to the movement in the arm/clamp arrangement? If it were me, I'd remove the LNB and holder, check to see if there is movement between the arm and lnb mount, then replace the LNB holder [without the LNB ]and again check for movement. It may be possible that moving the LNB back and forth is causing the movement of the arm/ LNB clamp but this all points towards a mechanical problem with the dish, arm LNB assembly.

 

[Red alert]

In my experience, moving the LNB from fully forward to fully back usually varies the signal quality by about 15% to 20%. What is the quality level prior to moving the LNB? I agree, the LNB alignment does look odd in the photo but is this due to the movement in the arm/clamp arrangement? If it were me, I'd remove the LNB and holder, check to see if there is movement between the arm and lnb mount, then replace the LNB holder [without the LNB ]and again check for movement. It may be possible that moving the LNB back and forth is causing the movement of the arm/ LNB clamp but this all points towards a mechanical problem with the dish, arm LNB assembly.

Signal level was 15% to 20% lower across sats. That was without tilting the lnb up. I only added the tape to lnb holder so that it remains in a tilt up position. When i get the time ill remove the tape and see if something really wrong mechanically.

 

[Trust]

This photo taken with head height at lnb shows it pointing higher than the middle bolts of the dish. Shouldnt this be resulting in lower signal than a high one. But at this position im picking up higher signal across many sats. How is this so? @a33



@sonnetpete when i push the lnb forward so the back hits the holder then signal becomes 0%

If you did setup the dish and motor with that taped lnb holder , I think your dish elevation is wrong .
You must set the lnb holder as original and solid , and adjust the dish elevation .

 

[sonnetpete]

Just to give you an idea what the holder and LNB position should look like...

 

[Red alert]

If you did setup the dish and motor with that taped lnb holder , I think your dish elevation is wrong .
You must set the lnb holder as original and solid , and adjust the dish elevation .

I did the setup without the tilting. After i couldnt peak the dish beyond 70% i decided to investigate the lnb. The lnb holder was not loose. When tilting i noticed signal started to climb.

 

[Red alert]

Just to give you an idea what the holder and LNB position should look like...

Comparing this to my setup a few months ago it looks like my lnb holder is tilted slightly more upward than yours. Your holder looks slightly more straight or im just seeing things
@sonnetpete can you please provide a photo showing the front of lnb so i can compare?

 

[jeallen01]

..... It may be possible that moving the LNB back and forth is causing the movement of the arm/ LNB clamp but this all points towards a mechanical problem with the dish, arm LNB assembly.

Weird "left of centre" thought! - could it be that the current arm is actually one from a smaller XP-series dish and so is shorter than it should be for the OP 100XP? (here is the Gibertini webpage on the specs for the XP series - but it doesn't give the feedarm lengths)?

If that were the case then the arm would locate the LNB holder nearer the dish, and lower than it should be, and thus the LNB would be "aimed" lower on the dish face than it should be, and so would have to be tilted upwards to be aimed at the "sweet spot".

Thus, could you and @Red alert measure the lengths of your respective arms (the ones on the dishes, not the ones you are "wearing" ) to check that they are actually the same length?

 

[Red alert]

Mine is approx 65cm measuring from back of lnb arm.

 

[antrabe]

one question, the dish inclination which one did you set up?

 

[Trust]

@Red alert according to your location the satellite beam for Thor is 28.6º elevation .
The offset angle of the Gibi OP100 is 21º , so pointed Thor the frontline of your dish should be 28.6 minus 21 = 7.6º leaning backwarts .

 

[Trust]

looks OK to me

 

[sonnetpete]

Mine is approx 65cm measuring from back of lnb arm.

Interesting, I measured the arm on mine and it's 75.5cm from the back of the dish face mount to the LNB holder. Also attached is a shot of the LNB taken from the front...

 

[Red alert]

Interesting, I measured the arm on mine and it's 75.5cm from the back of the dish face mount to the LNB holder. Also attached is a shot of the LNB taken from the front...

75cm from back of dish goes half cm beyond back of lnb, so looks like i have been provided with shorter arm. Im missing 10 cm it seems. @jeallen01 was right. Explains why i have to tilt lnb

 

[jeallen01]

Weird "left of centre" thought! - could it be that the current arm is actually one from a smaller XP-series dish and so is shorter than it should be for the OP 100XP? (here is the Gibertini webpage on the specs for the XP series - but it doesn't give the feedarm lengths)?

If that were the case then the arm would locate the LNB holder nearer the dish, and lower than it should be, and thus the LNB would be "aimed" lower on the dish face than it should be, and so would have to be tilted upwards to be aimed at the "sweet spot".

Thus, could you and @Red alert measure the lengths of your respective arms (the ones on the dishes, not the ones you are "wearing" ) to check that they are actually the same length?

75cm from back of dish goes half cm beyond back of lnb, so looks like i have been provided with shorter arm. Im missing 10 cm it seems. @jeallen01 was right. Explains why i have to tilt lnb

Mmmm.... When @Red alert said that his dish arm was 65cm, I thought that's far too short for a 1m dish! - and that now seems to be the case!

 

[Red alert]

Mmmm.... When @Red alert said that his dish arm was 65cm, I thought that's far too short for a 1m dish! - and that now seems to be the case!

Plus I wasted over 3 months trying to fine tune the dish and never worked. I will notify the shop.

 

[sonnetpete]

75cm from back of dish goes half cm beyond back of lnb, so looks like i have been provided with shorter arm. Im missing 10 cm it seems. @jeallen01 was right. Explains why i have to tilt lnb

Hang on, I measured from the back of the mount for the dish face, not the back of the dish. Maybe we should have agreed where to measure the arm from. Anyway, the smaller series of Gibertini has a totally different style of LNB arm and your photos don't show this. I looks like a pukka XP arm.

Check out the XP series home page. Gibertini SRL :: X Series Antennas

Make sure your arm is locked into the hole at the base of the dish face mount. I'm a little disadvantaged because I don't have the dish assembled at the moment I'm also confused, did you loosen the LNB holder to tilt it and improve reception or did you find it was loose and moving it helped? If it was loose it would be easier to rectify that and realign the dish elevation