It seems that the Norsat 3220 LNB has very little rejection of 22kHz on its supply (and maybe a general lack of rejection to any supply borne noise). I was testing LNBs on SES6, 40.5W using the beacon on 3947.5H. Switching to the Norsat as a reference I noticed sidebands on the beacon. At first I thought that either the synth had developed problems or data had been switched on the beacon. It turns out that I had left the 22kHz enabled and the Norsat is very susceptible to it. The 1st plot...
Norsat 3220 C band LNB Warning
Norsat 3220 C band LNB Warning