If you plan on using a 1.2 meter offset dish then I recommend you use the flat scaler ring that comes with the LNBF. Any dishes smaller than 1.2 meter or f/d ratios greater than 0.55 seem to work better with a conical scaler. Currently I am using a 1.2 meter offset dish with a DMX241 LNBF and a metal socket inserted within the inner ring at 3:00 oclock position. I tested the BCS621-2 LNBF on this setup, it worked well for KU but C-band was a little weak. The BCS621 has a gain of 68db and a noise figure arournd 18K. The DMX241 has a sligthly higher gain around 70db, but the noise figure is significantly lower around 13K upping the signal quality greatly and bringing in a lot more C-band channels, almost all of them across the arc on the 1.2 meter dish. The addition of the metal socket to the scaler jumps the signal level and quality significantly!
I am attaching photos of my motorized 1.2 meter dish for C-band and the motorized KU 76cm dishes on my garage roof. Currently I am using a diseqc switch to select either the 76cm KU dish or the 1.2 meter C-band dish. However I beleive there is now a C/KU combo with the same specs for C-Band as the DMX241, possibly its the DMX741. I plan on purchasing one of these new combo LNBfs this spring and putting it on the 1.2 meter dish, then take down the 76cm dishes from the garage roof.
I am very happy with my mini bud, picking up FTA from all satellites from 139W through 55.5W, can't get any further east as there is a lot of trees to the east of the yard. Your test results may vary, dependent of your location. I live a few miles east of North Bend, roughly 40 miles northwest of Omaha NE. Here in the center of the nation is a hot spot for most satellite signals.
Your biggest obstical in setting up a dish like this is getting a sturdy mount and attachment from the motor tube to the dish that holds up in high winds. Next is finding the right placement of the LNBF. I will have to take a photo of the degree markings on the LNB tube and mounting bracket to give you a rough idea of where to start, I will try to do this and post back later today with the photo. The next thing is the placement of the scaler ring; as you move the ring toward and away from the dish you will find it peaking a several positions. The maximum peak appears to be when the scaler ring is at is closets position to the dish with the Feed tube extending about 1/8 inch into the rings.
C-band has added roughly 20 real quality FTA channels for me in addition to what I am receiving from KU. Of course to each his own, there are tons more Cband I receive, but would not watch on a regular basis. The wife would never allow me to put up a large Cband dish, the size of the 1.2 meter is just right. Come this spring she will be happy when I take down the two 76cm dishes from the garage roof. Then I will have to find a great permenant local in the side yard for the C/KU band combo dish. Maybe she will let me install two!
Here I maybe comparing apples to oranges, but most Cband signal levels are above 80% strength and 90% signal quality. These results are from the Coolsat 5000 receiver. There are some channels with lesser quality, RFDTV for example on 103W receiving at 72% signal quality but has good picture and audio even during inclimate weather. Speaking of weather, these photos where taken before the last snow storm, getting tired of digging out once a week! You should see the drifts in the back yard; 8 to 10 feet deep from the snow that blew off the corn field!