I dont see any benefit to
grounding the dish.. or the LNB.
First off, the dish and LNB are not connected to each other.
And second what are the chances lightning would hit your dish, let alone the LNB.
If your LNB had a spiked, I think your unit may get burned w/ or w/o ground, no?
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Fortec 80cm dish, Univ LNB.
Fortec Classic NA
Captiveworks 600S Premium.

C-band 10ft dish, with Echostar 4000 IRD.