Ok... My question and the reason for asking it was based upon fatally flawed thinking!
I am setting up a 1.2metre dish for QO-100.... I have an Green Octogon Quad LNB
I chose the Quad LNB because I want to feed & run my Air-Spy SDR independently of the amateur radio download/upload side...
Ok, so I thought a good strategy would be attach my little Edision Progressiv HD Sat Tuner
and to initially line the dish up onto the Sky Satellites @ 28.2E
That all worked well... So the next step was to pick a FTA DVB-S transponder on the commercial Es'hail satellite and tune the dish up on that as a precursor to accessing the QO-100 Amateur Transponder...
That failed to work and it took a while for the penny to drop as to WHY? But, Hey! this is all a learning curve... But it was so obvious that I should have realised it in the first place !!
So what was the flaw?