With heavy Norsat LNBs and Chaparral feedhorn you need to play with the arms to get the focal point right. I can tell you it's a royal pain in the ass. I have a 6 foot Fortec pointed at AMC1 and an 8 foot Fortec pointed to AMC10. The only reason I use these dishes is for the ground mount. With the 6 footer, I use it only for DW-TV. Certain parts of the year, reception is perfect, and other parts it is sub par. Right now, most of the day the reception is good enough to produce a stable picture, and around 9PM the signal gets blocky.
With the 8 foot Fortec, I use that for the Weather Channel digital on AMC10 transponder 24 H digicipherII. It's the same reception as for AMC1, where parts of the year the reception is rock solid, and other parts, like now, reception is good enough for most of the day, and around 11PM, it falls below the threshold to produce a slightly blocky picture, like with DW TV on AMC1 with the 6 foot Fortec. Also, I use a heavy Norsat LNB and Chaparral feedhorn on the 8 foot Fortec too.
I want a Prodelin 2.4M but really has no ground mount like the Fortec that can be mounted like the ground mount. I'm not sure why the Fortec dishes have these reception problems, but I'm dying to get rid of them and get a decent commercial dish to eliminate these reception problems.