Invacom LNBFs: Twin or Quad interfering

kenglish · #1 (**permalink**) 02-24-2007, 05:50 PM

I had something wierd going on with the Invacom Circular/Linear Quad LNBF QPH-031.....sometimes I got a signal, and sometimes I didn't.

Changed it out with an Invacom Universal Twin TWH-031.

I am using two different Fortec receivers, fed by the two outputs of the LNBF. What seems to be happening is, when both receivers are operating (powered on), they both have to be on the same polarization, or neither one will receive a signal.

Aren't "twin" LNBFs supposed to have two completely independent outputs, for feeding two separate receivers? I'm wondering why this is happening? Crosstalk of some kind between the two receivers?

I'm now thinking this might be why the Quad was seeming to be flakey.

brentb636 · #2 (**permalink**) 02-24-2007, 09:08 PM

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.

N4ST · #3 (**permalink**) 03-02-2007, 07:58 PM

I am feeding two FTA receivers and one DirecTV receiver from my Invacom Quad with no signs of interference/crosscoupling. I often have all three receivers on simultaneously (even when I am the only one home

).

rainman · #4 (**permalink**) 03-03-2007, 02:00 PM

it maybe a problem with your coax cross feeding try new cable or separate your cables and see what happens.

wejones · #5 (**permalink**) 03-03-2007, 03:05 PM

One other thought. Are both receivers plugged into the same circuit? If not, perhaps there is a ground problem between the two receivers. If so, it could be that the DC sent to the LNBF has different ground potentials from the 2 receivers,which could confuse things. Haven't thought this senario out, but you might try making sure both receivers have the same ground.
I had a DC power supply once that was sending +6/-6 to one piece of equipment, and had another supply sending +12/0 to another connected to the first, and that really confused things.

kenglish · #6 (**permalink**) 03-05-2007, 06:42 PM

Last night, I tried swapping the two RF cables at the receivers, and again at the LNBF (the "twin").

Either way solved the problem. Now, I wonder if the LNBF has a blown steering diode or something......I'll try one of the other LNBFs in a day or so. Then, the quad, too.

It's been waaaaay too cold to do much lately, but it's warming up this week.

Thanks.