Can you guys ID this Dish ?

john_robot

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Feb 24, 2008
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Can you pls identify this dish ?
 

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Looks good size. 1.8 possibly? If so and it is free grab it. I think it is a fixed mount these old eyes could not tell, but just make sure to string test it when you assemble it If it's 6 foot like I think, the parobola set perfect, it will suck some signals.
 
The mount and feed support are different, but the dish looks like the 2 that I have.

 
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The mount and feed support are different, but the dish looks like the 2 that I have.

Hi, yeah mount is not orginal. Do you have photos of your dish pls ? Do you know what brand it is ? I need to get the correct focal length.
 
But this is a offset dish.

No problem. Though the equations to use are a bit more complicated.

See here: http://www.john-legon.co.uk/offsetdish.pdf
"Calculation of the Focal Length of an Offset Satellite Dish Antenna" by John Legon.

and here, for easier depth measurement, at the center, to start with: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwje_-6_u4zuAhVCx4UKHeTYDSsQFjABegQIAhAC&url=https://www.sat4all.com/forums/applications/core/interface/file/attachment.php?id=331743&usg=AOvVaw0skN2xOv8IwWCIqvpUfF_I
(does that link work? Or else you can download that .pdf here: Schotel nameten Or here, but you have to be registered I believe: Just Sharing This - Calculation of the focal length of an offset satellite dish antenna, Revisited )
"Calculation of the Focal Length of an Offset Satellite Dish Antenna, Revisited" by A33.



I have made my own calculator for that (in english language), and know of two calculators on the internet (in russian and french) that can do the calculations faultless. (In fact I know of 2 other calculators, that alas have one or more faults.)

Greetz,
A33
 

BTW: After some puzzling, I found a more direct way (without Google, inbetween) to link the file:
www.sat4all.com/forums/applications/core/interface/file/attachment.php?id=331743&usg=AOvVaw0skN2xOv8IwWCIqvpUfF_I


Edit:
And here is a drawing of the relevant points in the geometry of the offset dish, showing the difference of measuring depth at the deepest point, and depth at the center:



Greetz,
A33
 
Last edited:
You can always measure the dish (to mm exact, and depth to 1/2 mm exact!), and then calculate the position of the focal point?

So, when you need help for the calculation, just say so!

If the dish face is flat, the inputs Height and Width of the dish, and Depth (to 1/2 mm exact), are enough. But of course all three measured without the rim!

Greetz,
A33
 
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Another, more primitive but still effective practical method to find and locate focal spot of unknown dish - is to use a few small glass mirrors, located in random places on the dish and wait for a sunny weather. The small mirrors can be bought from craft stores or Dollar Tree and could be temporarily attached to dish by thin 2-sided glue tape or magnets or other means.
The azimuth and elevations of the dish have to be unlocked and the dish should be moved until all reflections of these few (3 - 7 or more) mirrors converge into one spot. Then the needed measurements can be made.
I tried to promote this trick many times a few years ago and hoped that this
method were included in "sticky'' threads, but it did not get there... that's why many members once and again inquire for methods to find focal spot for unknown dish.
Greetings,
polgyver
 
A friend of mine has an article on measuring the accuracy of a dish but you should be able to use a similar setup for finding the focal point. Start with his basic setup but instead of having the laser pointer perpendicular to the sliding bracket shown in the article, make it able to rotate to the approximate offset angle of the dish, then scan looking for the focal point and adjust the offset angle until you can scan the entire length of the dish and have the laser stay in the same target area.

I did something like this once to a mobile satellite uplink van where someone whacked and bent the feed on the 2.4m Ku dish on the van roof. I stuck a strip of shiny aluminum tape across the long and short sides of the dish surface then scanned both axis with a laser pointer and was able to bend the feed arm back to its original shape. Dish accuracy checking with lasers ...de N6CA
 
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