Fine tuning a dish

[Fizbi]

Ok, I'm going to start over.

I'm going to assume my dish is warped or the LNB arm is bent.

As I've said before, one of my two sons WHACKED my 85cm FTA ku dish with an umbrella, meaning they hooked the LNB with an open umbrella as they went sailing past it. I've got a pretty good feeling something is not quite true.

Though I get most of the birds just fine, I still cannot get 87W.

Poking around different forums I found this trick...

" replaced the LNB with a torch to check that the LNB was pointing towards the centre of the dish. Mine was miles out".

If nothing else, I'll get better at setting up a dish.

 

[rv1pop]

The centre of the dish -- mean the exact centre is NOT totally CORRECT for offset, or MOST, FTA KU dishes. That is why they are called OFFSET dishes. It should be centered side to side, but not up and down. I could be very wrong, but that is what I remember. Do not panic. get more information. Those with wisdom and knowledge will correct me.
POP

 

[Fizbi]

It should be centered side to side, but not up and down.

You are right. It is offset, so I need to check to make sure it is centered from side to side. That is my first step. But, I may take it down to see if it's warped first.

I also need to find a torch that will fit the LNB holder.

 

[phlatwound]

Somebody talked about using one of those little laser pointers to check their LNB aim, that sounded like a pretty slick deal.

 

[Mr Tony]

or a flashlight

I do that with my 6 footer all the time

 

[TRG]

or a flashlight

:haha I was thinking acetylene torch and that didn’t make sense, why woud he use that. Then I remembered someone calling a flashlight a torch in a BBC movie.

 

[Fizbi]

Offset Dish Information

A visit to wikipedia.org/ has a very good link to an article about offset dishes:

http://www.qsl.net/n1bwt/chap5.pdf

1. They are more efficient than non-offset dishes
2. Aiming the LNB for top/bottom and side to side center is good enough

Cool.

I can see I will have a lot of fun this weekend. :

 

[rv1pop]

with the colonies spelling of center spelled 'centre' torch would be the English word for the "colonies" flashlight

 

[Fizbi]

Warped Dish

All right. I pulled my dish down and laid it on a flat surface. There is a bad warp. The LNB alignment looks fine using a flashlight.

I pulled all the brackets off and did some minor bending. There is a dimple or crease in the edge from shipping. I managed to flatten out the dish so it's much truer than before. Put the dish back up and just finger tightened all the bolts.

Now the real fun begins.

I adjusted the dish angle and zeroed onto 119 W for NASA.
I went WEST watching the arc. I get 70+ to 97 Q for 119, 123, 129. Sweet.

Going east from 119, nothing.

I have more work to do.

What is strange now is I have to elevate the dish quite a bit to get anything east. My guess is the dish warp allowed me to get birds east and west even if at weaker Q.

It looks like I need to work on my arc. I see in another post that goaliebob99 has an arc problem and there is a graphic on how to troubleshoot arc problems.

So far, at least, I'm getting a stronger signal overall, just poor tracking for the arc. :up

I'll check my plumb. It's also possible the motor angle indicator could be off.

Lastly, while listening to the motor, it sounds like it is changing speed at times. I don't recall it doing that when I first bought it. Not sure what to make of it, but it is hitting perfectly on my WEST birds.

 

[Lak7]

Make sure you have the proper LNB L.O. for the Linear Sats.

 

[Fizbi]

Make sure you have the proper LNB L.O. for the Linear Sats.

LNB LO is correct as I was getting the EAST birds before I unwarped the dish.

I was getting:
ONN on 74W, Pentagon on 103W
Never got 87W (my goal).

I think I need to tilt my motor up and adjust my dish angle accordingly.

 

[Lak7]

I would start from scratch, 107 is your True South Sat but not much there. You could use USALS to drive to 110 or 103 to set up to. You could then bounce between those 2 to get on the Arc.

 

[Fizbi]

Spinning Wheels...

I've been making adjustments all afternoon.

If I start at 103, I get a good signal.

As I swing towards 95W, I have to increase the dish elevation.
As I swing towards 129W, I have to decrease the dish elevation.

I tried lowering and raising the motor angle and I get the same results.

Looking at the picture "Philosophy of Tuning Dish to Satellite Arc", it looks like the north/south axis is too far west. What does that mean? Does that mean I need to rotate my motor more to the east?

 

[Fizbi]

Mission Control...The Eagle has landed!

...Looking at the picture "Philosophy of Tuning Dish to Satellite Arc", it looks like the north/south axis is too far west. What does that mean? Does that mean I need to rotate my motor more to the east?

I'll answer my own question, "YES".

Wooo-Hoooo! Got it working. I actually stayed up, working in the rain, with a flashlight, in the dark, playing with my dish.

So, it looks like I had two problems:
1. A warped dish
2. My dish arc was a couple of degrees off from the actual SAT arc.

I'm now getting some great readings across the whole sky, even in the rain.
As an extra bonus, I picked up my missing 87W bird. I'm still missing a couple of FTA channels here and there, but now I just need to do some very minor adjustment to pick those up. Who knows, I may even get those when the wind and rain stops.

A big thanks to Lak7 :up for posting the arc map troubleshooting guide (in another post) as that is what I needed to get my arc problem resolved.

 

[gabshere]

its a great feeling when everything starts to fall into place
hope you enjoy

 

[Lak7]

I'm glad to hear.
Enjoy.

 

[Mr Tony]

CONGRATS!!

I'm now getting some great readings across the whole sky, even in the rain.
As an extra bonus, I picked up my missing 87W bird.

sweet Now you can add PBS to the list of networks you get

I'm still missing a couple of FTA channels here and there, but now I just need to do some very minor adjustment to pick those up. Who knows, I may even get those when the wind and rain stops.

do you know the specific channels? Its probably due to the rain. Some channels go kaput in light rain

 

[iafirebuff]

I thought i was the only one that went out in the dark and rain to "tinker" CONGRATS! Now ENJOY!