Motorized dish setup headache

[tttsheridan]

I managed to hook up a 1m dish with a motor on a ground stand. But when I configured the motor, I found out the SNR, SGC and BER of a Hotbird transponder barely changed no matter how I pointed the dish-I even put a frying pan in between the reflector and the LNB, but nothing happened. SNR was about 59, SGC fluctuated between 72 to 91, and BER was something like 8224.
I pulled out the cable from the LNB and SGC became zero.

My location: 32.9 N, 13.0 E.
My equipment: DM500s, 1 meter dish, Diseqc H-H motor with gotoX function,
dish mount stand(with upright pole).
My setting: motor mounted on the stand at an elevation angle of 57 degree, dish bracket angle about 24.6 degree. Numbers from motor manual.
I used the quick installation method. After assembling the hole unit, I just needed to point the dish to a roughly south position, selecte a favorite satellite and have it driven to the correct position with the help of receiver's gotoX function. Finally all I did was rotate the motor assembly around the pole to find the strongest signal from the selected satellite.
But I saw no change in signal strength however I twisted and turned the dish!

What is wrong? I'd appreciate if you give your advice here.

 

[Lazarus]

Couple of points for starters:

1. Your figures look ok, as 32.9N does indeed equate to setting the Motor Elevation to 57. However, many H-H Motors have a "Elevation" scale on one side of the bracket and a "Latitude" scale on the other: Do double check you've set the right figure against the right scale!

2. The "results" you report are nothing more than telling you the LNB is connected and powered up (But I guess you've twigged that by now .....)

3. You cannot achieve real alignment to your favourite Satellite (Hotbird in this case) just by altering the motor/dish assembly - you must also adjust the dish bracket as necessary. You can't just set and hope - the dish bracket angle of 24.6 is only valid for a system with absolutely no mechanical errors in eg Pole verticality. It is vital you treat this as an approximate starting point and then account for errors, including lack of precision in setting the motor bracket (quite hard to get reliably more accurate than half a degree or so) by adjusting the dish bracket angle as part of the final alignment process.

Basically, the answer to your question "what is wrong" is probably that you are overshooting or undershooting the Satellite - a few tenths of a degree at the dish bracket translates to a heck of a "miss" at a point 24,000 miles away!

 

[satelliteman]

Have you taken a browse at the set up guides? Dish Setup Guides, Information threads and FAQs

Having a longitude of 13°E simplifies the installation somewhat as motor can remain on zero and you align up on that satellite; observing the above motor installation settings of course (inclination 57, and a rough dish EL of 24.5°).

What DiSEqC motor is it?

 

[tttsheridan]

Thank you Tivu and satman.
I think I should be more patient and tweak it more.

I've read the tutorials in case I am asked to read them...
I have not checked out the FAQs yet.

The motor was bought from a local satellite shop. Brand and model is STAR NET V-240 diseqc HH motor.

 

[Lazarus]

I think I should be more patient and tweak it more.

That's about the size of it!

 

[satelliteman]

Ah, the dish elevation using that motor (due to a 35° shaft) will be approx 30°. Again dish elevation markings are fairly inaccurate but and a starting point and is of good info

 

[tttsheridan]

Hi, Super Moderator Satman. Do you mean I need to set my dish elevation angle at approx 30° instead of 24° ?

 

[Lazarus]

The data table supplied with the Motor is the oracle - or it should be.

However, I note that that is what you used to arrive at the 24.6 figure.

If that is wrong and Paul is right, that means your "miss" is potentially massive!

In the end, you still have to tweak it anyway, so I think an empirical solution (suck it and see) would apply.

Let's face it, you could set it by eye to halfway between the two suggested figures, at around 27.5 deg, and toss a coin as to whether you try aligning by reducing it a bit at a time or by increasing it a bit at a time ...............

 

[satelliteman]

Hi, Super Moderator Satman. Do you mean I need to set my dish elevation angle at approx 30° instead of 24° ?

Well if the motor is what I think it is, then on paper, yes. But in practice the offset dish needs to face slightly up as a starting point. It's very well documented here that elevation brackets are indeed inaccurate but some dishes can be close to spot on; the FR Penta being one.

 

[tttsheridan]

You guys are a beacon of hope to me!

 

[john_graydon]

It took me 2 days to put mine up, so theres always hope.
If you had a sat meter that would help, and also to make sure your pole is dead straight. Mine was a bit off and I think that was my problem.

 

[tttsheridan]

Have you seen dish bracket like this?
It has one scale running from 0 degree to 30 degree and another from 40 degree to 0 degree.
I don't know how to set the dish elevation angle!

 

[Lazarus]

The bracket is designed for "universal" use ie can be assembled in two ways to give (as you know) different Elevation ranges, thus enabling it to be used over a greater range of latitudes.

My brain is not yet fully engaged this morning, but for your location in Libya, I suspect you will have to assemble it using the 0-40 range.

However, this is yet another indefinite variable in the debate about what the starting Elevation really should be and I still maintain you'll be better "sucking and seeing".

May I suggest you remove the motor for now, and just mount the dish direct on the pole. Then align it to Hotbird in the manner of a single fixed dish, using both of the bracket assembly methods in turn until you succeed. This shouldn't take very long at all and has the great benefit of removing, by experiment, both of the Elevation issues ie Calculated starting value and bracket orientation.

You will simply be able to observe the attitude of the dish and ensure it is replicated when the motor is re-attached. Sufficently so to be confident you will only need a few small tweaks, anyway.

That's what I'd do, rather than worrying too much about pesky theoretical variables and inadequate assembly instructions.

 

[tttsheridan]

Thank you very much for your time and input.
I will try using the 0-40 scale and see what happens.

 

[tttsheridan]

With you guys' help and some meticulous efforts on my part, I managed to lock my motorized dish onto Hotbird 13e and some other channels.
The rest, I suppose, is just some fine tuning.
Ooooh yeaaah!

 

[satelliteman]

Nice result. Worth checking both ends of ther arc and adjust on due South accordingly.

 

[Lazarus]

Very good indeed!

I always think it better in the long run to experience a few difficulties as the act of resolving them contributes much to understanding and makes one far more confident for future installations and re-alignments

 

[john_graydon]

With you guys' help and some meticulous efforts on my part, I managed to lock my motorized dish onto Hotbird 13e and some other channels.
The rest, I suppose, is just some fine tuning.
Ooooh yeaaah!

Well done, some fine tuning with the motor and elevation will get you the lot. Remember to mark your dish & motor, just in case.

 

[tttsheridan]

Thanks again, my friends!
Hope I can successfully track the satellite arc.

 

[tttsheridan]

I must admit I was very wrong to assume just some fine tuning is left to accomplish my mission the day before.
I could still use you guys' expert guidance. :-worship

This afternoon my "motorized"(not that motorized yet) dish ran into another set of problems when I tried to track other satellites.
First of all, I tried to locate Niltesat 7W and lock more transponders than I had got. But nothing came along. Signal strengths were about 59 again.
Then I wanted to call it a day as it was getting dark. As soon as everything was adjusted back where there were, I found only a few channels were there on Hotbird. I thought it was because the motor did not move to the correct position, so I tried driving the dish to point to Hotbird.
Worse still, the motor must have been sick of being driven so often that it refused to budge an inch. I had to unplug the receiver several times in order to trigger the motor or to reboot the dead receiver.
At last, the motor did move for some times or for some distance and the goto 0 function worked okay too, but it could no longer go past 5 degrees west or east.
Tonight someone was beating his brains out. When he tuned into some movie channels he saw the signal readings were really bad. Finally with a bit of luck, he figured out he could hold the green Go button for a few seconds and lock the desired channel. And if the channel went off, he needed to repeat that locking method again.

Backlash? Long cable and low voltage? Mounting pole not vertical enough in the first place? Please kindly give me some suggestions based on the above description. Thank you!