how do I find right length to face lnb to the dish

[mrel]

Hello
Is there a forumla to find the focal point of an offset dish .
What is length of lnb arm should be point to the dish.
Found (label say mizushi )dish at swapmeet the dish did not have lnb arm and some other missing parts.
The size of the dish around 120cm.
mrel

[space86]

Is it a Dish 1000 ?

[bruin95]

Wrong forum. Post this question in the FTA section.

[Ext 721]

Wrong forum. Post this question in the FTA section.

Cover that sucker carefully in tin foil. smooth out all the wrinkles until it is as smooth as you can get it, and as close to a mirror as you can.

Then, use the sun.

or...

If the dish has elevation marks, compare the elevation marks to the dish face. What elevation does it read when the dish face is vertical? This will tell you the offset (or do we need to divide by half....hmmm.....)

Formulas would require you to measure the curvature of the dish (as in, how many degrees of curve for every meter/yard of surface...that's not easily done with any accuracy.

Much better to use the foil method. It will give quick and reasonably accurate results without having to measure the inner curvature of the dish...just keep moving that puppy until you get as small a blob of light as you can. Put the LNB there, angled so it faces the dish center.

[FTA Michael]

Or Google search until you find a matching dish, then either try to get a replacement arm or a good look at an assembled dish and arm.