When I connect IBU a Sat Finder immediately gets noisy even while LNB is on the ground. When I connect Inverto C120 or GI-209P using the same cable there is no noise coming from Sat Finder. I was thinking maybe a cable conductor is not long enough for LNB connectors to make a proper connection...
Finally I got a few LNBs for PFA and wanted to test them today. I removed IBU which I used on my PFA and replaced it with Inverto C120 + feedhorn, but turned out it doesn't show any signs of life. After that I replaced that one with GI-209P and again the same story, no signal. With IBU it works...