focal point setting

Latest News and Discussion about the use of the DATV transponder on Es'hail-2
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Posts: 77
Joined: Thu Nov 21, 2013 5:29 pm

focal point setting

Post by sean2e0saf » Thu Sep 05, 2019 12:33 am

anyone give any pointers on focal point setting prime focus IRTI 1.5m dish i measured the original FP to be about 625mm from the tip of the scalar rings on the original feed horn.. i assume i simply use these same measurements for new lnb and patch antenna waveguide then i put the cap on..?

thanks all
23cms AATV from io83qn ( wn68ns )
23cms DATV from i083qn ( wn68ns )
70cms DATV from io83qn ( wn68ns )

wimo shf-2344
parabeam 70cms/18ele

Posts: 21
Joined: Fri Apr 12, 2019 9:29 am

Re: focal point setting

Post by RimaNTSS » Thu Sep 05, 2019 4:05 am

It is always possible to calculate. You just need to precisely measure diameter and depths of the dish and then enter data in some of the calculators, like this ... lector.htm
Make sure feed is pointed to the center of the dish. Also move feed closer/further and observe when signal lever gets maximum.

Posts: 314
Joined: Wed Jan 06, 2016 9:46 am

Re: focal point setting

Post by radiogareth » Thu Sep 05, 2019 6:53 am

As above, measure and calculate. I was able to 'prove' by using the sun and putting a small piece of paper to 'see' the focused sun - but my dish is clean alloy - no paint. You can also use your hand......with care if its a big dish - mine is 66 cms and it gets hot!

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