Trouble aligning a CM dish on a CM polar mount

[Chr0nik]

Hi,

I'm having a issue trying to align my CM 120 with the Channel Master polar mount after moving everything to the roof of the house.

The pole is plumb on all 4 sides and but I'm confused on the elevation/declination values I need to setup on the polar mount.

For the elevation rod, based on my location (51.477 N, 0.311E) do I need to set it to 51 or to 38.5 (51.477-90)? and regarding the declination, I understand that the value is (22.5 + 6.1=28.6 ). I've tried to set these values using a digital inclonometer but the angle of the dish seems off and cannot set the declination value without changing the value on the elevation rod.

I've been doing a lot of reading for a long time and spent quite a lot of time on the roof trying to get it working (the neighbors already thing I'm weird and have complained) but I cannot get this working so I would really appreciate your assistance.

I will post pictures when I get home.

Thanks!

 

[ozumo]

Forget the scale on the rod and put your digital inclinometer like this (if it small enough) and set it to to 51.48

 

[Manikm909]

does it not have elevation one side, and latitude on the other, i'd try 51, then peak dish to 1w, and see what happens on 30w and 45e - if no good, change to 38 - align to 1w again and see...

sorry mate, only have experience in DISEQ motors.

why do the neighbours complain!? can u see into their windows? i would be helping you not complaining.

 

[Chr0nik]

Forget the scale on the rod and put your digital inclinometer like this (if it small enough) and set it to to 51.48
View attachment 135710

Thanks! I will try that - what about the declination?

does it not have elevation one side, and latitude on the other, i'd try 51, then peak dish to 1w, and see what happens on 30w and 45e - if no good, change to 38 - align to 1w again and see...

sorry mate, only have experience in DISEQ motors.

why do the neighbours complain!? can u see into their windows? i would be helping you not complaining.

Unfortunately, the roof is right next to their extension which is their bathroom so when I go up there to align the dish, it seems like I'm outside of their bathroom window. Unfortunately my house is not a south facing one, so there are a lot of limitation when it comes to this hobby.

 

[Channel Hopper]

Unfortunately, the roof is right next to their extension which is their bathroom so when I go up there to align the dish, it seems like I'm outside of their bathroom window. Unfortunately my house is not a south facing one, so there are a lot of limitation when it comes to this hobby.

Next time, go out on your roof naked and if they look at you go complain to the authorities about peeping toms next door.

 

[ozumo]

Thanks! I will try that - what about the declination?

I set it till it to where it looked about right (Dish leaning slightly back for me), moved the dish a few clicks towards 1W, then rotated the mount in the hope of finding 1W. Once found I adjusted the declination to peak 1W, then moved the dish to see how it followed the arc. Ended up rotating the mount a couple of degrees, adjust the declination a small amount to peak 1W and then try again, did this a couple of times until it followed the arc.

You can measure the skew of the dish using your inclinometer, just make sure the meter is vertical while taking a reading. Find out what your skew for 1W is and move the dish until it is skewed correctly, then rotate the mount to peak 1W.

 

[a33]

The pole is plumb on all 4 sides and but I'm confused on the elevation/declination values I need to setup on the polar mount.

I would use the so-called modified motor angles, e.g. as in the chart this post: Polar Mount Setting Declination Angle
(Inbetween angles, not mentioned in the chart, can also be calculated.)
That way you follow the arc better, than with the 'traditional motor angles' (such as: axis elevation = 90 - your latitude).

It is always very important to check if the angle is meant against the vertical, or against the horizontal!
There are several pictures on the internet that use incorrect terminology.
This picture at sattv.info I think is rather good (though not the whole website is correct, I found!):



NB1.: I usually use the term 'declination offset angle' (more precise), instead of 'declination angle'.
NB2.: 'Polar axis angle' in the chart = 90 - axis elevation angle ('elevation with correction').

Does this help?

Greetz,
A33

 

[Manikm909]

Thanks! I will try that - what about the declination?



Unfortunately, the roof is right next to their extension which is their bathroom so when I go up there to align the dish, it seems like I'm outside of their bathroom window. Unfortunately my house is not a south facing one, so there are a lot of limitation when it comes to this hobby.

my sky dish is next to my neighbours "Kids" bedroom, whenever i need to work on it, i knock and tell them im about to work on the dish, and to understand that they will see me by the window etc etc - they really appreciate it and dont complain

 

[Manikm909]

Next time, go out on your roof naked and if they look at you go complain to the authorities about peeping toms next door.

no, dont do that.