Offset dish LNB position ??

[g6agz]

Appologies if this is the wrong section for this question.
I have aquired a 1 metre offset dish / polar mount /jack etc.
However there is no LNB arm with it. I forgot to ask the guy I got it off ( free ) about the arm.
Is there ANY way of telling where the lnb should be?
Prime focus easy , use the sun. BUT offset???
do I just get another dish for the mount or is there a way?

 

[CROSSBONES]

Try and find out what make of dish it is, post a pic of it, some one will probably recognize it.

Then give you the measurements;)

Failing that there are formulas too work it out

 

[g6agz]

I found a dish for sale on ebay that looks exactlythe same as the dish I have..I did bid on it but lost out by 50pence ... drat

http://i75.photobucket.com/albums/i291/g6agz/dish.jpg

I have asked the seller to measure the arm and this may be my best bet but any help would be good.......