I have a dish pointed at 61.5 with a single LNBF. Can I just take off the LNBF and put on the new 1k.4 LNBF without readjusting the dish angle? I don't think it will be possible but just want to quickly check. I don't want installers touching my junk so I'm going to do it on my own. BTW, my dish is 18". Do I need a larger dish? I think they have 21" or 34"...