simple lnb question

[zcubed]

Hi,
I know this is a stupid question, but here goes:
I don't know about dish installing. I had mine "professionally" done (it was a kid that showed up). Anyway, i was told about single lnb and dual lnb, and that if you want to run two or more receivers then you need a dual lnb dish, multiswitch, etc. So, i just took it at that and didn't worry about it. Now, my friend is getting into the hobby. He just bought a single lnb walmart system. He asked me why he couldn't split the signal from the single dish and run it to two receivers. I told him it just doesn't work this way. He kept asking why it wouldn't work, and i couldn't answer him. He wanted me to ask the den, so i am. Thank you.

[zcubed]

A little clarity --
when i said split the signal to two receivers, i mean to set it up so the recievers can view channels independently such as would be the case if they were on a dual lnb. Thanks.

[smack]

The signals coming from satellites (applies to 101 and 119) are polorized (Left-Hand-Circular - LHCP and Right-Hand-Circular- RHCP)...roughly a 50/50 split...half of the channels are LHCP, half of the channels are RHCP.

Each individual LNB can go one way other the other, LHCP or RHCP, but not both at the same time. The polorization is selected by changing the voltage to the LNB, if ~18VDC is sent (from the receiver), then the LNB looks at the LHCP signals...if ~13VDC is sent then the LNB looks at the RHCP signals.

With one receiver (IRD), when you change the channels, the receiver changes the voltage as appropriate.

If you have two boxes talking to the same LNB, and one is trying to watch an RHCP signal and the other is trying to watch a LHCP signal, then the LNB is gonna switch to LHCP (higher voltage wins).

If you have a "DUAL LNB" there's actually two LNBs under the cup, with two external connections for the RG/6 coax. Each receiver talks to it's own LNB, commanding the LNB to switch according to the channel that each of the receivers are tuned to.

If you have more than two receivers, then a multiswitch is necessary for the same reason mentioned above.

To use a standard two-in, four-out multiswitch (a "2X4"), you MUST have a dual LNB...that's rule #1, and it's in concrete.

The multiswitch is a group of switches, either mechanical (relays) or electronic (silicon...like a transistor). In a situation where some of the receivers are watching programming sent on a RHCP signal and others are watching programmingsent on a LHCP signal, the multiswitch energizes the LNBs such that one is "tuned" one way, and the other is set the opposite. The multiswitch then feeds the correctly polorized signal to the receiver (it knows who wants what because of the voltage level sent by the receiver).

Within each block of polorized signals, there is a range of frequencies available to be selected...just like TV or radio...the signals are always there, you tune to the frequency within the block that you want to listen to. The multiswitch has sent the LHCP or RHCP block of frequencies, now the receiver can select the correct frequency within that block that's appropriate for the channel you want to watch.

More-often-than-not, the multiswitch will keep one LNB at LHCP and one at RHCP for faster channel switching if it can.

SO, again, splitting a signal from a single LNB doesn't work in a normal setup because the receiver presenting the higher voltage level will always win at the LNB. Many splitters aill drop, divide, or block the voltage to the LNB and you only get half the channels available (Scan for "Only getting the ODD transponders" ..there's a sh*tload of 'em, and most are from people trying to use splitters, or have bad cable (drops too much voltage, can't get to 18VDC), or crummy connectors, or flakey grounding blocks.

Sometimes trying to use a splitter can smoke one or both receivers (depends on the splitter, and how it's hooked up). There are some splitters on the market that lead you to believe that they are for splitting one dish to two receivers...it ain't so. Printing a satellite on the face of the splitter does not impart enough of the correct magic into the splitter to get it to work in this fashion (splitting dish to multiple receivers).

Now...to (hopefully) cut off the few that'll try to correct me on that point: there are some special splitters that WILL split one LNB to two receivers BUT it's still a bad idea, you have to know EXACTLY what to buy, and know EXACTLY how to connect it...and it's STILL a bad idea...Dual LNBs are not that expensive, multiswitches are not that expensive. Do it right or get cable TV (IMHO).

Hope this help to clear things up. Good Luck.


FWIW

Scott

[SMOKER]

Well said smack.....wow....I've tried to put into words just what you said a hundred times and still keep it simple for the guy that is just going to install one dish. Your post just proves why your the answer guy.

[zcubed]

smack,

Thank you so much for the response. Very, very informative. I really appreciate it. Even non-technical people such as myself and my friend are able to understand the concepts you mention. My friend always questions why things are the way that they are. This will set him straight. Thanks again.

zcubed

[EAO]

THIS IS EXCELLENT,I'VE ADDED A LINK DIRECTLY TO YOUR POST WITH THE DETAILS IN THE INFO THREAD IN MY SIGNATURE BELOW

.IT MIGHT JUST ANSWER A ? BEFORE A THREAD IS STARTED.


. NICE JOB,THANK'S FOR SHARING IT.




Originally posted by smack
The signals coming from satellites (applies to 101 and 119) are polorized (Left-Hand-Circular - LHCP and Right-Hand-Circular- RHCP)...roughly a 50/50 split...half of the channels are LHCP, half of the channels are RHCP.

Each individual LNB can go one way other the other, LHCP or RHCP, but not both at the same time. The polorization is selected by changing the voltage to the LNB, if ~18VDC is sent (from the receiver), then the LNB looks at the LHCP signals...if ~13VDC is sent then the LNB looks at the RHCP signals.

With one receiver (IRD), when you change the channels, the receiver changes the voltage as appropriate.

If you have two boxes talking to the same LNB, and one is trying to watch an RHCP signal and the other is trying to watch a LHCP signal, then the LNB is gonna switch to LHCP (higher voltage wins).

If you have a "DUAL LNB" there's actually two LNBs under the cup, with two external connections for the RG/6 coax. Each receiver talks to it's own LNB, commanding the LNB to switch according to the channel that each of the receivers are tuned to.

If you have more than two receivers, then a multiswitch is necessary for the same reason mentioned above.

To use a standard two-in, four-out multiswitch (a "2X4"), you MUST have a dual LNB...that's rule #1, and it's in concrete.

The multiswitch is a group of switches, either mechanical (relays) or electronic (silicon...like a transistor). In a situation where some of the receivers are watching programming sent on a RHCP signal and others are watching programmingsent on a LHCP signal, the multiswitch energizes the LNBs such that one is "tuned" one way, and the other is set the opposite. The multiswitch then feeds the correctly polorized signal to the receiver (it knows who wants what because of the voltage level sent by the receiver).

Within each block of polorized signals, there is a range of frequencies available to be selected...just like TV or radio...the signals are always there, you tune to the frequency within the block that you want to listen to. The multiswitch has sent the LHCP or RHCP block of frequencies, now the receiver can select the correct frequency within that block that's appropriate for the channel you want to watch.

More-often-than-not, the multiswitch will keep one LNB at LHCP and one at RHCP for faster channel switching if it can.

SO, again, splitting a signal from a single LNB doesn't work in a normal setup because the receiver presenting the higher voltage level will always win at the LNB. Many splitters aill drop, divide, or block the voltage to the LNB and you only get half the channels available (Scan for "Only getting the ODD transponders" ..there's a sh*tload of 'em, and most are from people trying to use splitters, or have bad cable (drops too much voltage, can't get to 18VDC), or crummy connectors, or flakey grounding blocks.

Sometimes trying to use a splitter can smoke one or both receivers (depends on the splitter, and how it's hooked up). There are some splitters on the market that lead you to believe that they are for splitting one dish to two receivers...it ain't so. Printing a satellite on the face of the splitter does not impart enough of the correct magic into the splitter to get it to work in this fashion (splitting dish to multiple receivers).

Now...to (hopefully) cut off the few that'll try to correct me on that point: there are some special splitters that WILL split one LNB to two receivers BUT it's still a bad idea, you have to know EXACTLY what to buy, and know EXACTLY how to connect it...and it's STILL a bad idea...Dual LNBs are not that expensive, multiswitches are not that expensive. Do it right or get cable TV (IMHO).

Hope this help to clear things up. Good Luck.


FWIW


HISTORY
THREAD START - ZCUBE 2-26
3 POSTERS

SMACK POST - FEB 26,2001

LAST POST IN THREAD PRIOR TO THIS 2-27,2001

5 164 October 10th, 2001 07:57 PM #'S AS OF THIS POST
6 559 December 10th, 2001 10:21 AM

7 mos 164 before link 23+ vpm
2 mos 395 after link 197+ vpm



Scott

[bballfreak]

I installed a new oval dish 18x24 with 2 dual LNBs pointing to 119. It did not come with a multiswitch. I bought a TERK multiswitch, with 3 -in and 4 -out. I am not using the 18" dish.
There are 4 coax connections coming out of the oval dish , two from each LNB. I connected only one from each LNB to the TERK, one says 13V and another is higher voltage. I did not know which one should be connected to what?? The center one on the TERK is for the air-antenna which I have not hooked up.
Then, I connected one older Sony receiver to the one output and it works OK. I connected a second output to a SONY-HDTV receiver and I do not get a ATR, is it because of my connections. Do I need a multiswitch to begin when I am using only the oval dish??
Please help!!

[EAO]

Originally posted by bballfreak
I installed a new oval dish 18x24 with 2 dual LNBs pointing to 119. It did not come with a multiswitch. I bought a TERK multiswitch, with 3 -in and 4 -out. I am not using the 18" dish.
There are 4 coax connections coming out of the oval dish , two from each LNB. I connected only one from each LNB to the TERK, one says 13V and another is higher voltage. I did not know which one should be connected to what?? The center one on the TERK is for the air-antenna which I have not hooked up.
Then, I connected one older Sony receiver to the one output and it works OK. I connected a second output to a SONY-HDTV receiver and I do not get a ATR, is it because of my connections. Do I need a multiswitch to begin when I am using only the oval dish??
Please help!!

i'm by no means an expert on this.but i did install a multi with a dual lnb round dish. i had my problems and therefor read quite a bit.

a dual lnb round dish set up has only 2 connections coming out of the dish.

you have 2 from each lnb. the oval dish is used to get both satellite's. i'm only assuming but the reason you have 2 on each is because one is for 1 sat and the other is for the other.

the ird's i believe only have 1 sat in connection.
so somehow those two coax's must be combined. i would imagine the instructions would tell you how.
if you bought this as a pkg with the ird's all the h/w and switch's necessary should be included.

i'm going to assume you brought the dish as a replacement or add on .
still i would think it wold give you the necessary h/w switch's/combiner to install it.

well on 2nd thought if either of those was true you probably wouldn't be asking the ?'s your asking.

so it's 2nd hand no instructions and no addt'l h/w.

there's something you need to combine the 2 lines into 1. i don't know what but a search here should help to answer that ?
or maybe someone will correct what i'm saying or give you the parts required.


the one you describe has 2 sat in's and a tv ant in. the 4 outputs go to 4 ird's.

i didn't use the tv input but from reading you need something else for it to work. i think it's called a diplexer and that's needed because of some technical reason having to do with the difference between how the sat's handle the siagnal and a tv antenna.

you only need the multi switch if you are hooking up 3-4 ird's.
if you need the multi,after you find out whats needed to combine the 2 lines in to 1 from each lnb then you can proceed with the installation.

it doesn't matter which coax goes to which sat input.

WHATS MOST IMPORTANT FOR EVERYTHING TO WORK IS THAT YOU MAKE SURE YOU INSTALL EACH F CONNECTOR PROPERLY.

YOUR GOING TO BE INSTALLING A LOT OF CONNECTORS WITH JUST 2 IRDS,BUT WITH THE MULTI THERE'S MANY MORE.

A BAD CRIMP/STRIP WILL CAUSE YOU THE MOST PROBLEMS.
that's from expierience.

give the details on how many ird's. and where you got the dish from.

hope this helps

gl

[EAO]

as i mentioned above i thought the 2 lines on each lnb were for delivering the 101 and 119 sat's signal. and they must be combined.

seems there's a 4x2 multi that is 4in from the dish and has 2 out's. thise 2 outs would go too 2 ird's sat in or to the 2 sat ins in a 2x4 multi that has 2 sat in from the dish which is then distributed to the 4 ird's sat in.

here's the link

http://www.dsschat.com/forum/showthread.php?postid=379164&highlight=%2Acombine%2A#post379164


there is also mention of a combiner but i'm not sure if it's the same

[EAO]

it seems you have to have a specific switch for dtv oval/ellipticall dish set ups.

the link to the thread confirfming you need a switch that combines the 4 outputs from the oval/ellipticall dish into 2 outputs at least.

http://www.dsschat.com/forum/showthread.php?postid=197903&highlight=%2Acombine%2A#post197903

the dealer link that sells the 22khz switch says it's its no longer available.

i'm going to check the dealer links from my research when i was going to buy the multiswitch to see if they offer one.

[EAO]

OK HERES A LINK TO A 4 INPUT 4 OUTPUT MULTI.

IT SAYS IT FOR 2 SATELITTES ETC.. MAY OR MAY OT BE THE RIGHT SWITCH BUT IT SEEMS IT WOULD. IT'S UNDER 22KHZ SWITCH'S AND FROM READING THE THREADS/POSTS THAT'S WHAT'S MANTIONED AS BEING NEEDED FOR THE DTV SYS.

http://www.channelmaster.com/pages/22k.htm

THAT'S IT

[EAO]

HERE'S A LINK TO THE SWITCH AND THE DESCRIPTION SAYS ITS FOR DT> PARATODOS MULTI SATTELITE SYSTEMS. PRICY

http://www.starkelectronic.com/newstuf.htm

YOU NEED A MULTI SATELLITE MULTI SWITCH.
THE ONE YOU HAVE I BELIEVE IS ONLY FOR A SINGLE SAT DUAL LNB DISTRIBUTION TO 4 IRD'S.

DO YOURSELF A FAVOR AND BUY A RG6 CABLE STRIPPER.
YOU CAN'T BUY THEM AT RAT SHACK. YOU'LL ONLY FIND THEM WHERE PRO INSTALLERS BUY THERE EQUIP. THAT SITE PROBABLY HAS IT.




GL