I have BEV on 91W and am south of Phoenix by about 60 mi and I am missing about 8 transponders but when I go NE about 150 mi I get all my transponders with my RV 18" dish. I found this out last spring. This winter I tried a 24" here in Florence AZ and still miss 8 transponders both odd and even numbers. Should I try for a 30" dish or am I S O L Any help would be appreciated