I've been running two receivers off my
Invacom QPH031 since June last year, and haven't seen that problem. Been using a Buzz Plus,
Classic NA, Ariza Xtreme, Merc II, and ExtremeView Magnum on the lnb.
I would take my receiver out to the lnb with a TV and see if I had the same problem there. You are correct that the lnbf's are isolated from each other. By the way, it's called a "dual output" or "dual" lnbf. A "twin" handles two different satellites.
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Searching the sky with a Fortec Star 80cm dish, Invacom qph031 quad LNB, STABS HH90 motor, on
a Buzz Plus .
And a Fortec Star 90 cm dish, Invacom QPH031, Moteck SG-2100 and a Mercury II.
The official neighborhood crazy guy !
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www.sadoun.com "