Polar Mount Setting Declination Angle

[wium78]

With the self built polar mount I will I go about measuring the elevation.

 

[Channel Hopper]

With the self built polar mount I will I go about measuring the elevation.

Is this polarmount as per the image in Post 1 ?

 

[wium78]

Is this polarmount as per the image in Post 1 ?

No my welder copied the image in post 1.

 

[Channel Hopper]

I assume the item imaged does not have declination markings.

Best to start with would be an inclinometer, but you can probably get away with a spectrum analyser and a compass, both of which you can sell later to recoup the costs.

 

[ArloG]

Digital angle gauges are cheap enough that nobody should purchase an inclinometer. With 0.1 to 0.01 degree resolution it's a no-brainer.
The CM/Raven/Andrews dish "look angle" is indeed 22.5 degrees. Think of a billiards table banking off a side rail. The lnbs 'sees' signals bounced off the dish face.
In #14. The red stripe is with the polar elevation angle pointed true North. The North Star. Same as a person with a telescope with equatorial mount would do when setting it up.
The blue stripe is off the back of the dish. Considering the 22.5 additional degrees that the dish is "looking" up in the sky. You would calculate declination by adding that to the given declination angle for a prime focus dish.
Of course with the dish then swung on the pivots so that it is as high in the arc, zenith, as it can be. The dish ten would be aimed at true South.
The the fun begins.
That's a nice mount. Too bad the photo is so small.

The blue wedge is how the dish would be on the mount with 22.5 degree look angle compensation.
The light green wedge is after declination is added. And the upper right illustrations show the effects.
The last diagram is where the fun begins and should clearly show how a digital gauge is superior to an inclinometer.

 

[Channel Hopper]

Digital angle gauges are cheap enough that nobody should purchase an inclinometer. With 0.1 to 0.01 degree resolution it's a no-brainer.
The CM/Raven/Andrews dish "look angle" is indeed 22.5 degrees. Think of a billiards table banking off a side rail. The lnbs 'sees' signals bounced off the dish face.
In #14. The red stripe is with the polar elevation angle pointed true North. The North Star. Same as a person with a telescope with equatorial mount would do when setting it up.
The blue stripe is off the back of the dish. Considering the 22.5 additional degrees that the dish is "looking" up in the sky. You would calculate declination by adding that to the given declination angle for a prime focus dish.
Of course with the dish then swung on the pivots so that it is as high in the arc, zenith, as it can be. The dish ten would be aimed at true South.
The the fun begins.
That's a nice mount. Too bad the photo is so small.

The blue wedge is how the dish would be on the mount with 22.5 degree look angle compensation.
The light green wedge is after declination is added. And the upper right illustrations show the effects.
The last diagram is where the fun begins and should clearly show how a digital gauge is superior to an inclinometer.

I suspect the North star is unavailable to the o/p

 

[a33]

My elevation is 47.91 how would I measured it against the pictured dish.

Where did you get that elevation value from? You are still at LAT = -34.4?

In that case your total elevation due south north is 50.0 degrees.
Dish face angle, taking into account the 22.6 degrees offset angle of the dish, would be 50 - 22.6 = 27.4 degrees.

Greetz,
A33

Edited: due NORTH

 

[ArloG]

Yeah. In my illustration the rear dish mount plate angle should be equal to putting a straight edge across the dish face. Dish on the pivots at zenith (highest in the arc). The same angle as the red line, your elevation angle. Which is your latitude.

Then tilting the dish down 22.5 degrees would put the look angle perpendicular, 90 degrees, to the red elevation angle.
With the dish set there. You would be tracking an imaginary arc above the equator. Where geostationary satellites are parked.
Then. Adding the correct declination to the dish mount. You let the dish 'peek' down at the satellites.

Love it when people add silly things.
Like. Maybe the OP can't see or find the North Star in the daytime. Neither can I.
Never the less. The same concept applies to an equatorial mount telescope. Which has a star finder that lies parallel with the red line in my sketches. The exact same as using the dish face or dish mount plate angle for setup. Exact.
Do you concur?

Edit:
Surprised nobody has mentioned dishpointer.com

 

[MrDish1]

Yeah. In my illustration the rear dish mount plate angle should be equal to putting a straight edge across the dish face. Dish on the pivots at zenith (highest in the arc). The same angle as the red line, your elevation angle. Which is your latitude.

Then tilting the dish down 22.5 degrees would put the look angle perpendicular, 90 degrees, to the red elevation angle.
With the dish set there. You would be tracking an imaginary arc above the equator. Where geostationary satellites are parked.
Then. Adding the correct declination to the dish mount. You let the dish 'peek' down at the satellites.

Love it when people add silly things.
Like. Maybe the OP can't see or find the North Star in the daytime. Neither can I.
Never the less. The same concept applies to an equatorial mount telescope. Which has a star finder that lies parallel with the red line in my sketches. The exact same as using the dish face or dish mount plate angle for setup. Exact.
Do you concur?

Edit:
Surprised nobody has mentioned dishpointer.com

Surprised nobody has mentioned dishpointer.com

It's out, just like so many Site's sometimes

 

[stcome]

Surprised nobody has mentioned dishpointer.com

It's out, just like so many Site's sometimes

see : www.dishpointer.eu
Thank you Sprietje/sat4all

 

[a33]

see : www.dishpointer.eu
Thank you Sprietje/sat4all

Dishpointer.com is only down on SOME computers. On my computer no problem at all.

Dishpointer.eu does not give declination offset angle, for motorized setups.
I would prefer the satlex website for angle calculation; see:

Dishpointer website

Did you enter your location, at the left? Did you choose "motorized systems", "true south/true north" (or a specific H-H motor type) at the right? Otherwise, can you share a picture of what appears on your screen? Then maybe we can understand what is the issue. greetz, A33

www.satellites.co.uk

Greetz,
A33

Edit: made the important sentence bold.

 

[wium78]

www.dishpointer.eu That web site confirmed my elevation as 47.91 at LAT -34.40. Using the pictured dish how would I measure the elevation.

 

[a33]

www.dishpointer.eu That web site confirmed my elevation as 47.91 at LAT -34.40.

Not for due north direction, as you would need for a motor setup.
I'd be pleased to see your confirmation for 47.91.


BTW. For due north, when using this website: when you are at LON 19.26, choose an (imaginary) satellite at 19.26.

Greetz,
A33

 

[wium78]

Latitude: 34.4° S
Longitude: 19.26° E

Satellite: 7° E

Azimuth: 339°
Compass: 365.8°

Sun:

Elevation: 47.9°
Skew: -17.2°

from dishpointer EU. I could be confused with motor set up as I use an actuator. Being in South Africa my dish must point North and using a polar mount I wish to track the satellites with footprint over South Africa.From a previous post must I accept 50 as my elevation as I dont have a satellite at North.I used 7E which is incorrect.Therefore,using the image in posting (1) how would I measure the elevation of 50?

 

[ArloG]

Start with the red line. This is your elevation, or latitude. Set it correctly. Lock it down.

Move the dish with the actuator so that it arcs in the sky as high as it will go. Look at my diagrams above.
The motor will unbolt from the actuator tube and you can then turn the shaft with vice grip pliers, screwdriver. Count the turns so that you can return it to the same point before the motor was removed.

The bottom of the square dish mount frame will be level. That proves your dish is highest in the arc.
And the dish can then be turned on the pole so that it is aimed true South. Remember. Not magnetic South.

The red and green lines must be parallel, the same angle.
Assuming the dish mount was built with the dish look angle in the design. Adjust the top bolt so that the dish lowers the specified declination degrees. Lock it down.

The blue line will then be equal to the elevation (latitude) angle + dish look angle of 22.5 degrees + the declination angle.

The intention then is to find the satellite closest to true South. You may not have a satellite at 180 degrees true South. Not magnetic South.
If at zenith the dish is aimed true South. Without rotating the entire mount on the pole. You should be able to tune your receiver to the closest satellite that is closest to true South.
And then manually turn the actuator screw to point the dish in that direction. Do try to keep track of the turns so you can return it.
Or we will end up in a tutorial of how to set the limit switches.

When you think you are close to your target satellite but cannot quite seem to snag it. Slight E-W movements of the dish and pushing down or pulling up slightly on the bottom of the dish rim will help relate to the arc diagram I added above.

I do not know what is with Dishpointer. A glitch? If you scroll down the satellite list to True North/South. The locator line should point true South and the dish setup data should show. With a Google Earth interface with aiming landmarks. This morning it did not. The UK site is too fancy-schmancy.

 

[wium78]

Thanks ArloG your input is appreciated.

 

[Channel Hopper]

Start with the red line. This is your elevation, or latitude. Set it correctly. Lock it down.

Move the dish with the actuator so that it arcs in the sky as high as it will go. Look at my diagrams above.
The motor will unbolt from the actuator tube and you can then turn the shaft with vice grip pliers, screwdriver. Count the turns so that you can return it to the same point before the motor was removed.

The bottom of the square dish mount frame will be level. That proves your dish is highest in the arc.
And the dish can then be turned on the pole so that it is aimed true South. Remember. Not magnetic South.

The red and green lines must be parallel, the same angle.
Assuming the dish mount was built with the dish look angle in the design. Adjust the top bolt so that the dish lowers the specified declination degrees. Lock it down.

The blue line will then be equal to the elevation (latitude) angle + dish look angle of 22.5 degrees + the declination angle.

The intention then is to find the satellite closest to true South. You may not have a satellite at 180 degrees true South. Not magnetic South.
If at zenith the dish is aimed true South. Without rotating the entire mount on the pole. You should be able to tune your receiver to the closest satellite that is closest to true South.
And then manually turn the actuator screw to point the dish in that direction. Do try to keep track of the turns so you can return it.
Or we will end up in a tutorial of how to set the limit switches.

When you think you are close to your target satellite but cannot quite seem to snag it. Slight E-W movements of the dish and pushing down or pulling up slightly on the bottom of the dish rim will help relate to the arc diagram I added above.

I do not know what is with Dishpointer. A glitch? If you scroll down the satellite list to True North/South. The locator line should point true South and the dish setup data should show. With a Google Earth interface with aiming landmarks. This morning it did not. The UK site is too fancy-schmancy.

For the o/p this might be better.

 

[ArloG]

For the o/p this might be better.

oops. s. of the equator. my bad