First of all :
83 deg E : Insat 4A
93.5 deg E : Insat 4B
Secondly Insat 4A c band : min dish size required is : 170 cm, catchable on 6 ft (180 cm) dish...
For Insat 4B Ku band : min dish size required is : 60 cm dish.,..
For c band use 13k lnbf if possible,
for Ku band use : Sharp lnb.. that is the best....
Thanks...