Question for the LNB/switch experts

968 Views 11 Replies 7 Participants Last post by bobnielsen, Dec 30, 2006

Brantel

Discussion Starter · Dec 29, 2006

I have a question regarding how the built in multiswitch works on the slimline dish.

Does the slimline actually have 5 dual LNB's feeding the built in multiswitch? If not, how does each LNB provide both even and odd transponer info per sat to the multiswitch?

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bonscott87

· #2 · Dec 29, 2006

It's exactly like the Phase III triple LNB dish. You have 4 independent outputs from the dish. If you only have 4 total tuners or less then you can run these directly to your tuners.

If you need more then 4 tuners then you need an external "cascadable" multiswitch. For the 5 LNB dish the Zinwell WB68 and their 16 port are the only ones that will work with the KA band for sure. I'm sure other companies will have compatable switches soon if not already. Make sure it is before you buy.

Any old multiswitch you have will not work with the 5LNB because it cannot get the KA band sats.

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harsh

· #3 · Dec 29, 2006

Brantel said:
Does the slimline actually have 5 dual LNB's feeding the built in multiswitch? If not, how does each LNB provide both even and odd transponer info per sat to the multiswitch?

In general, a DBS LNB does both even and odd as required. If they didn't, you would need two dishes as only one LNBF can be in the right place for each dish. In the case of the Slimline (AU9) and Behemoth (AT9), one of those horns is handling both Ku and Ka band.

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Brantel

Discussion Starter · #4 · Dec 29, 2006

Thanks, I fully understand this, this question is not related to your response, but deeper into the theory of how they work.

There are 5 sats picked up by this dish, I undersand that one LNB does the 99,101, and 103 combined. The others get 110 and 119.

My question is, how do these 5 produce both even and odd transponder signals. Are they actually two LNB's inside each of the 110 and 119 heads and six LNB's inside the 99,101,103 head?

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Brantel

Discussion Starter · #5 · Dec 29, 2006

harsh said:
In general, a DBS LNB does both even and odd as required. If they didn't, you would need two dishes as only one LNBF can be in the right place for each dish. In the case of the Slimline (AU9) and Behemoth (AT9), two of those horns are handling both Ku and Ka band.

It is impossible for 1 single output LNB to provide both even and odd transpoders at the same time. Otherwise we would have no need for switches.

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harsh

· #6 · Dec 29, 2006

Brantel said:
My question is, how do these 5 produce both even and odd transponder signals. Are they actually dual LNB's inside the 110 and 119 head and six LNB's inside the 99,101,103 head?

It helps to ask what you want to know directly.

The LNBs can change polarity electronically, so the big horn only needs three. For five satellites you need five LNBs. Note that some satellites are use a "circular" where polarity is not involved. Dish Network has three satellites with circular orientation.

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harsh

· #7 · Dec 29, 2006

Brantel said:
It is impossible for 1 single output LNB to provide both even and odd transpoders at the same time. Otherwise we would have no need for switches.

The job of the polarized Low Noise Block downconverter is to receive and separate the incoming high frequency polarized signals into lower frequency bands. The switch routes the required band.

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Brantel

Discussion Starter · #8 · Dec 29, 2006

Maybe this will help you understand what I am asking...

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P Smith

· #9 · Dec 29, 2006

Brantel said:
It is impossible for 1 single output LNB to provide both even and odd transpoders at the same time. Otherwise we would have no need for switches.

All of them are dual output LNBF (don't mix with Twin models, ie a block of TWO LNBFs getting signal from TWO satellites ).
As to one output LNBF, there are plenty of them - bandstacking models, Dish DP LNBFs also is same type.

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jdspencer

· #10 · Dec 29, 2006

Brantel,
It is actually a combination of your two diagrams. The 101 and 119 LNBs use both odd and even TPS, whereas the 110 only uses the even TPs. I'm not sure about the 99 and 103 sats. Anyway, the 110 LNB is of a special type that downconverts TPs 28, 30, and 32 to 8, 10, and 12 which are then combined with the 119 even TP signals. DirecTV doesn't use TPs 1-21 on the 119, thus this combination works. The receiver sends a switching signal to the LNB assembly to select which satellite it needs. Odd TPs are selected by use of a 13v/0kHz signal. The Evens by 18v/0kHz. For 110/119 a 22kHz signal is added. For 99 and 103 there is some other kind of signal used.

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carl6

· #11 · Dec 30, 2006

As jdspencer noted - and to better clarify the answer to your question - where both odd and even are used, the LNB assembly must be a dual LNB assembly in order to simultaneously provide both odd and even.

DirecTV transponders and corresonding LNB's use right hand circular polarization for odd transponders, and left hand circular polarization for even transponders. You are correct in your questioning - a single LNB is not able to receive or handle both simultaneously.

Where it gets a little tricky is the fact that not all transponders are used on all satellites, and the LNB/internal multiswitch electronics do frequency shift transponders in order to squeeze it all in to the four possible "request combinations" a receiver can send - 13V no tone, 13 volt with tone, 18 volt no tone and 18 volt with tone, which request 101 odd, 110/119 odd, 101 even and 110/119 even transponders, respectively.

So the internal multiswitch in the Phase III dish is really a 5 input 4 output multiswitch. Two for 101, two for 119, and one for 110.

Carl

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bobnielsen

· #12 · Dec 30, 2006

I haven't actually checked, but I believe that with the 5 LNB dishes, 99 is piggybacked with 101 and 103 is piggybacked with 110/119. The outputs are on different frequency bands so they can exist at the same time.

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