focal point setting

Latest News and Discussion about the use of the DATV transponder on Es'hail-2
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sean2e0saf
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

RimaNTSS
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 https://www.satellite-calculations.com/ ... 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.

radiogareth
Posts: 315
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!
Gareth

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