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HtoH installation uncertainty

K

kelvin

Guest
#1
After doing a great deal of reading about installing motorised dishes I finally got enough courage to have a go at fitting my 1mtr dish to an
H to H motor.

It was a bit hit and miss at first but eventually all came right and I was feeling quite pleased with myself until I read a post on another forum which conflicted with the way I did mine and now I'm unsure which way is correct.

Someone had asked for advice installing an HtoH in Dundee Scotland and the reply said he should add 3 degs to the zero setting because Dundee is 3 degs west of the meridian and that Astra should be 22degs and Hotbird at 16 degs, and he stated that this info is also in the Cryptic
manual.

When I did mine I set the motor pointer to slightly west of zero about 1 deg and the rotated the whole mount until I found Thor, but this persons method would have made it 2 degs east and affected the arc further east.

I wonder if someone could comment on this situation please and let me know which way is right.

Thanks kelvin.
 

rolfw

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#2
I think the big question Kelvin is does your setup work to your satisfaction, if so does it really matter about the methodology.

Rolf
 
K

kelvin

Guest
#3
Hi rolfw thanks for your reply and yes it does work well, and the reason I didn't raise the question on the forum concerned was I wanted to avoid my question being taken the wrong way as some people can be very sensitive about their opinions.

This forum is specifically about such matters and probably contains more knowledgable users on the subject, but my main concern was the guy in Scotland possibly receiving duff gen and maybe geting it all wrong.

Thank you kelvin.
 

rolfw

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#4
Hi Kelvin,

I think a lot of the confusion lies with the difference between true and magnetic north, but as I say, if it aint broke don't fix it. Aligning a motorised dish is more fiddly and time consuming than technically difficult and you've certainly gone one better than a lot of others who have had to resort to calling in a professional to finish the job.

Rolf
 
0

0101010101

Guest
#5
Basicaly Kelvin if you are 1 deg W, then 1 deg W Thor is at 0 degrees to you! You would only need to take the magnetic variation into account. If as Rolf says your dish appears to be OK leave it.
Have you have checked from say Turksat 1C at 42e http://www.lyngsat.com/turk1c.shtml
to PAS3 45w (Fox Sports 12578H)
http://www.lyngsat.com/pas43.shtml
If you have those two towards each end and Astra/Hotbird OK in the middle you have it about spot on! If the dish is very slightly out, take it very easy when (and if) adjusting!
 
K

kelvin

Guest
#6
Thanks guys for the info and 0101010101 you seem to agree with the guy who posted in the other forum who said because Dundee is 3degs west then Thor will be 2degs east, so what I really want to find out is if setting up a motorised system using Thor as a reference starting point, and the drive is an H to H type with a calibrated azimuth scale on the housing is it correct to align the pointer slightly to the right to estimate one degree, and then rotate the complete mount manually to find the Thor signal, or align the pointer with 2 degs east then find Thor by the same method because I am 3 degs west of meridian.

Of course using the 'find strong satellite' method rules out the need to consider the magnetic variation so I did not use a compass at all especially with the steel pole being so near.

Any further advice on the above two options would be appreciated.

Thanks kelvin.
 

Channel Hopper

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#7
Still not absolutely sure where the magnetic variation comes in if you are not using a compass. Satellite movements adhere to gravitational physics and the true poles, equator and the movement of the earth determine these, not magnetic variations (they do actually but only to a small extent)

Slightly off topic

http://www.un.org/Depts/unsd/demog/826.htm

will give to long/lat for all major towns and cities in the UK
 
K

kelvin

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#8
Hi Channelhopper it doesnt come into it because unlike people who have no reference satellite and have to use a compass I if you like used Thor at 1 deg west as a perfect compass giving me virtually the top of the arc.

kelvin.
 

rolfw

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#9
I think what CH was referring to was my mention of it Kelvin, the only reason I mentioned it was that it seems a lot of people get hung up on the compass direction thing, when what really matters is the physical setup.

Rolf
 

Channel Hopper

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#11
If you are stuck with using a compass and are worried about the magnetic deviation due to the metallic objects nearby, simply line up the needle with the install and walk away from it (both sides) and put markers in the ground where it lines up with the pole. Over ten feet or so you should get a pretty good idea which way is South (Gday - North for those viewers down under)

Doesnt work up a ladder though !
 

Channel Hopper

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#12
By the way 0101010101, your idea on where the satellite sits above you based on where you are is not quite right either

The further East or West the satellite is from the viewer, the lower or further declined the satellite will appear. This is due to the position of the satellite relative to the Earth (and hence its orbital slot designation) is based on center earth angle. Some of us however, are sitting on a thin crust about 3600 miles from thae center, so the viewed angle is somewhat less.

Eg a satellite at 40 degrees will appear to be at approximately 46/7 degrees, and any satellite at 73 or so degrees is effectively on the horizon.
 
K

kelvin

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#13
Hi again CH no I'm not stuck for using a compass and with my method theres no need to do so, but I still badly need an answer to my main question about the H to H mount zero setting.

Thanks kelvin
 

Channel Hopper

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#14
Your friend in Dundee has been given the right information, all satellites will appear to him exactly three degrees shifted to the East.

A polarmount or H to H system requires the user to have the centre line looking at a point that is effectively in line with the closest point to the equator, regardless of position, to accurately track the full arc of satellites.

This will be for a Dundee viewer, three degrees further West than a system installed say at Greenwich
 
K

kelvin

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#15
CH thank you for your succinct reply its exactly what I'v been trying to discover, but it does leave me with a big question mark over why my system which did not have the 3 degree correction applied is working so well over the entire arc.

My dish is on a five foot pole so I can easily check for any improvements at various points throughout the the arc by pushing the top or bottom of the dish to check for an elevation error and I can achieve absolutely none at all.

As I'v now found my dish was incorrectly set up I'm surprised at the results because at any point on the arc my dish must be either too low or too high due to it having its maximum elevation at zero degrees azimuth, and not at 2 degs east.

I suppose the question is how much difference in the polar mount elevation is created by a movement of 2 degs azimuth, not much I suspect, and if I was much further west of Grenwich say Ireland for instance then it probably would be significant.

kelvin