I am using a GT SAT GT-S40 Universal LNB that claims 0.2 dB NF. Usually 10 cad. I have not had the oportunity to test it in the same conditions versus others 0.5 dB NF units or 0.2 dB NF or any other Linear or Universal LNB to give an opinion. not yet, at least.

I also read yesterday about 121W AMC 21 on the SatelliteGuys.US forums giving problems to 123W G18 reception. Like you say lyngsat does not list anything. I beleive some SatelliteGuys.US user wanted to try to find an anwser using a Spectrum analizer or something similar. In my case apparently I aimed the dish more toward 121W therefore nothing from 123W interfered me.

My offset 90cm Fortec complays with the 2 degrees spacing (+- 1.97 degrees signal goes down 3db) so theoretically if aimed properly it will not get interference from either neighbour Sat namely 121 and 123W respectively. But 1.97 gives me a very narrow margin for mis-alignment. The skies are crowded this days therefore the need for a bigger dish. Minimum to complay with the 2 degrees spacing is 90 cm or 36" so in your case the 33 " at 11700, the -3 dB cut off would be beyond 2 degrees. I do not remember the exact values and it also depends on the manufacture quality of the Dish itself (quality of the surface , warps or whatever you call it) but if you search the before mention website you will find the values. A bigger Dish will be your solution apparently but the interference could be a temporary problem , maybe they are testing those TP or who knows. Time will tell.

Donnyjaguar, you mention the focal point. I have not been able to find any documentation pertaining to the focal point of my 90 cm Fortec Star Offset Dish. So far I have been assuming the LNB bracket was designed to grab the LNB by the neck and very close to the head , so therefore I always locate the LNB head almost touching the bracket itself. So far I can not complain about the results obtained even with the motor and the pole not perfectly plumb but someone told me that your are suppose to attach the LNB by the middle of the neck. Of course being an Engineer, I asked a few questions more (to check the backgroud knowledge of the person) and realized that maybe that knoledge was probably based more in practical trial and errors results which in my opinion are very important to take into account but I guess it was easier for me to set the skew properly if the bracket grab almost the head (where the reference scale is) of the LNB. What is your experience/opinion on that?

You are right the typical LO stability of a cheap consumer grade LNB is +- 1 Mhz. Imagine the cheap FTA Box!!!!.