Is it possible to get international channels from AMC-16 which is at 118.75 as well as Echostar 7 which is at 119 with the same LNB?
Is there a dual LNB that can accomodate wide band starting at LOF 10750 MHZ and be able to recieve frequencies of 10700 to 12200 in 118.75 and 12200 to 12700 in 119.
Finally can a 18" dish good enough to catch 118.75 or a 30" dish absolutely necessary.
I would very much appreciate your experience in this regard.
30 inch Dish is an absolute mininum for 118 (118.75 Linear Polarization). You can try to use an Universal ( both Linear and Circular) LNB to get 119 and 118.
However, 118 transmitts weeker signals, so you must aim at 118 to get the best possible signal, and 119 (circular) will be the secondary (whatever you can get residually).
Because you are optimizing with 118 (Linear polarization), you might have better luck with a 33" Dish so your secondary 119 satellite will have a better signal.
But in NO WAY you can get it with an 18 or 20 inch Dish and expect to get 118 without investing big $$ on supplemental amplifiers and equipment.