Some Declination angle confusion

Vipersan

Hi ..
I do hope someone can explain my confusion..

I'm trying to realign the following setup

SG2100 not the (a) version

Triax 110 offset dish.

My location is Lat 53.5N Long & -2.35W

The Motor Elevation has been set at 90-53.5 = 36.5

At my location the Declination angle for the dish is 7.6

To calculate the dish angle for the bracket setting I assume 30-7.6 = 22.4 for the SG2100 ...to accomodate the bend in the motors drive mount..

The problem is that with the offset on the dish bracket scale set to 22.4 ....I get nothing from Thor at 0.8W ...or indeed from any other sat in the arc ..
If however I slide the dish bracket sliding scale to around 25>26 ..and I do get signals from 0.8W ...and although not perfect tracking ...signals at 13E and 8W etc.
This is a pig of bracket to ajust as it isn't just hinged ...and theres a lot of weight in the dish.

Can someone suggest what I'm doing wrong here ..
All the info I can find suggest the dish bracket angle should be 22.4 ...but I find it only works at 25 or there abouts.

Is it maybe possible the dish bracket is on upside down ?
I assumed not as the numbers would then be upside down...but I may be wrong..

Does anyone have a scan or pdf for Triax Dish ? ..sadly I didn't get one when I bought the dish.
Maybe that would shed some light on the mystery.
Any help would be most welcome

Finally and slightly off subject ...can the zero position move on this motor ?
If so ...how reliable is manually nudging the motor to zero ...and pushing a pin into the reset hole.
Does this then fix the zero point correctly ?

rgds
VS

satelliteman

Hi and welcome to satsuk,

The El brackets are NOT reliable on TD dishes at all. As long as you've followed the set up guides you should be able to track the arc correctly.

Also see explained > H-H DiSEqC Motor polar axis angle, declination offset and dish elevation

satelliteman . ..... A Detailed DiSEqC Motor Installation Set Up Guide > HERE Quick Reference Guide also > HERE Satellites UK site Advertisers . An Installers Choice ...... Follow us on .

rick1980

I have the TD 110 and the elevation scale on the dish bracket isn't accurate for anything other than a rough guide. Set your motor right, then adjust the dish angle to suit.

Vipersan

Thanks for a very quick reply to my question Satelliteman ...
I suspected the bracket might be out but assumed it would have to be within a reasonable tollerance ..

The reason I've started re-aligning my setup in the first place was due to not tracking the arc correctly ...
Oddly I could always trac the western half of the arc from 1W to 58W with very acceptable results ...but in order to track the Eastern half beyond Astra at 28deg ...I had to move the usals offset E/W beforehand ..

Can you identify from this what aspect of my setup alignment has been moved during last years freaky winds ?
rgds
VS

Huevos

Should be 35.8.

Vipersan

Thanks for your reply Huevos..
You have managed to confuse me even more

I thought my calculation was correct ....
I've just fould a lookup table for the SG2100 ....and it too sugests the motor elevation should be 36.5 ..
Could you please explain why Im wrong ?
rgds
VS

rolfw

Surely your Moteck also has a latitude scale on which you can directly set your latitude setting without using any calculation?

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Vipersan

Indeed it does rolfw ...
Due to the motors location its difficult to get a ladder to the other side of it ..to read from the scale..
I'll have a go with a mirror ..
rgds

satelliteman

In practice this setting isn't that imperative and close enough is normally sufficient.

It's fairly straight forward to set the angle (Latitude or El) by the marker on the motor and then when doing up the 4 bolts on the motor bracket the whole thing moves a fraction.

If installing from new, to be dead accurate, you can do as shown in the diagram, assuming the pole is dead plumb to start with that is. Turn upside down to set the angle.

satelliteman . ..... A Detailed DiSEqC Motor Installation Set Up Guide > HERE Quick Reference Guide also > HERE Satellites UK site Advertisers . An Installers Choice ...... Follow us on .

RdMin

I set my motor to 13E as these were my strongest tps,and got all other sats in the arc from there.!,I use a motek HH motor on an 80cm dish,managed to bolt everything together handtight and adjust accordingly before nipping everything up.try _www.dishpointer.com for all the relevant angles/directions of sats for your area.

Good Luck

Huevos

Most setup guides say this but it is wrong. If you adjust it as per your calculation it will set the polar axis of the motor completely parallel with the polar access of the globe. That's ok when the objects you are aiming at are at infinity because they are all an equal distance away. When you are aiming at geo-sats though they are at different distances from you because you are not dead centre in the orbit. Your due south satellite is around 4000 km closer to you than those at the ends of the arc. This means you need to point downhill a bit more to line up on your due south satellite compared to those on the ends of the arc. If you don't add this compensation you will be high at either end of the arc by nearly 3/4 of a degree. If you only have a small dish and are only interested in a few high power satellites around the centre of the arc it's not going to matter much to you, but with a medium or large dish you might as well give up trying to receive weaker signals at the ends of the arc if you have that level of misalignment.