LNB with two cables

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Rickles

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#195661 28-Apr-2016 23:09

My daughters house has a satellite dish with an old dual-throat LNB that has two cables coming out of it. Inside, there is a plate with two F type terminals.

I've seen lots of LNB's, both the old dual and the latest single throat types, but all seem to have just one cable.

What were these two cable beast used for? I'm assuming it is pretty old, and nobody would buy two set-top boxes or Sky boxes etc?

DjShadow

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#1543710 28-Apr-2016 23:50

The 2nd cable is for the part of the LNB that can pickup Optus C1/D3, if you remember back to 2006 I think it was when the old Optus Satellite had a failure and moved out of position cutting everyone off for a little while. The idea being Sky could move services onto C1 to keep everyone going. Also I believe the intention was they were going to use the newer D3 for services but this never happened.

Rickles

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#1543711 28-Apr-2016 23:54

Thanks Carl, I thought it would be something like that.

DjShadow

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#1543713 28-Apr-2016 23:57

Can't remember which way around it is but if you goto chan 998 you will get the Optus C1 test and 999 will give you the D1 test

RunningMan

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#1543719 29-Apr-2016 00:20

The second (and 3rd & 4th on some LNBs) are just additional identical but independent outlets. As the cable to an LNB is bidirectional it means multiple tuners or receivers can each operate independently choosing what satellite and polarity signal they want from the LNB. Basically, the LNB has a built in multi switch with 2 or 4 outputs. Each output can send whatever polarity or satellite that the receiver asks for.
Sky did this for a while some time back so that if they ever started using other than H pol on D1 then multiroom and multi tuner boxes wouldn't have t compete for which got the signal it wanted at any given time.