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Thread: Add a offset Ku LNB to a prime focus dish that is 2.3 meter, Possible??

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    Question Add a offset Ku LNB to a prime focus dish that is 2.3 meter, Possible??

    Hi tried to us a 6'solid prime focus to get I-19 c band didn't work good, so used old 2.3 meter prime focus mesh dish and locked in C-band very good
    Found out the solid was steel and checking it found out under the paint very rusty all over and soft. and in some spots all over you could put your fingers through
    it.
    So could I mount a offset Ku band LNB on the same dish I know mesh does not work with Ku as good as C band for the Ku signal is thinner. But if i could use more of the dish to get more of the signal At least I can try the using a motor lock on to a C-band part of the next satellite and then look at the Ku side.
    Any body tried this?



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    You can buy a dual band lnb for c/ku have two i use now .The problem with the rust is it degrades the signal as the dish is not parabolic any more
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    Quote Originally Posted by hinekadon View Post
    You can buy a dual band lnb for c/ku have two i use now .The problem with the rust is it degrades the signal as the dish is not parabolic any more
    Thanks for the info the 2.3meter mesh dish is Alum all over solid built bought it about 15 years ago haven't used it for years so moved it next to my "man cave" my garage, I'm on I 19 and lot has been lost with changes to the hash mode. I looked a new one but the quality was not in it at all.
    So please send me the model number of your c-ku lnb and this would fit into the cband ring? Or does it come with a scaler ring?
    We used a C ku feedhorn combined a chapparel i think

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    Hi, the ones I use are the WSI model ns741 the reason is the kuband is on the back and you can move to in 90 deg s as its plastic and screwed on to the back of the c bander , some times i cheat a bit and use the ku seperate with a long round waveguide to a modified c band scalar ring . as they are a little more sensitive than the norsat ku lnbs . the top cover just snaps off so you can set up the c band hoz/vert easily and the skew for ku . Any how bought of fleabay cheers don
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    If you have a C/Ku feedhorn, just add a Ku LNB to it.

    Being a commercial-quality feedhorn, a separate Ku commercial LNB will have superior performance compared to a combined single C/Ku LNBF, which is a compromise on both bands to begin with.

    Whilst it can work with an offset LNBF, they are designed (obviously) for an offset dish, so there is signal loss when using them on a prime-focus dish, plus add to that, losses on a mesh dish.

    If possible, for best performance, use a separate solid dish for Ku.

    You could then combine the two dishes signals with a multiswitch.

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    We better get it straight ? are you [planning to offset a ku lnb beside you c band lnb or you have both mtv and myself confused with a offset dish lnb or offsetting a lnb , I got the impression you wanted to use a lnb dual c/ku lnb on a prime focus dish ???
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    Quote Originally Posted by hinekadon View Post
    Hi, the ones I use are the WSI model ns741 the reason is the kuband is on the back and you can move to in 90 deg s as its plastic and screwed on to the back of the c bander , some times i cheat a bit and use the ku seperate with a long round waveguide to a modified c band scalar ring . as they are a little more sensitive than the norsat ku lnbs . the top cover just snaps off so you can set up the c band hoz/vert easily and the skew for ku . Any how bought of fleabay cheers don
    I looked yours up on the intert and it looks like the one I'm getting can I use the same cable if so please give me some info.
    Thanks for you quick answer what part of the world are you in/ i am in Queensland near Brisbane Australia

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    yep the same cable is ok I use rg11 most of the time and crimp f types but that double sheilded rg6 is ok as well. avoid rg59 too lossy
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    Quote Originally Posted by hinekadon View Post
    You can buy a dual band lnb for c/ku have two i use now .The problem with the rust is it degrades the signal as the dish is not parabolic any more
    Dual LNB's are not that good they lose lot of signal both C & Ku.It is better of getting additional Ku LNB and attach it to the feed horn.
    Location: Sunny Perth

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    what instruments have you got to backup this story ???? sorry i dis agree with you there is no extra losses using a dual feedhorn with a ku lnb aligned correctly as opposed to single lnbs as the input signal is the same regardless what type of lnb you use , the length of the feed is enhanced by the removal of side lobes from the original input , and the losses from a stepped waveguide are less as well so what proof do you have ???? sorry you are under a misconception
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    I think tmsani is referring to a combination C/Ku LNBF, which are indeed a compromise.

    Separate LNB's on a waveguide combiner on a separate feedhorn work extremely well.

    The OP hasn't answered my questions about the feedhorn/combiner I asked to clarify.

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    Default lnb s

    In my tests the inline lnb shows a little more "gain" as there are no extraineous signals to degrade the amplification factor of the front end , such as those that come from side lobes and terrestial noise certainly multiple frequencies thru various wave guides suffer less than the imposed frequencys at the feed point due to the cutoff antennuation of the waveguide . ie the c band travels best thru a c band wave guide as a round wave guide with miniscule losses the ku travel thru the same area but with everything below c band cut off then only allowing ku band freqs to enter the ku lnb and nothing less there fore the lnb preamp has a cleaner signal to work with and is working where it was designed to work

    Sorry I missed out one part on your question yes you can use the same cable but you have to install a disq sw to decide if you want c or ku . that is your two feeds go into a sw and is decided by your reciever . ok now , please answer mtv question from earlier post ??? don
    Last edited by hinekadon; 15-09-19 at 09:14 AM. Reason: more
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    Quote Originally Posted by hinekadon View Post
    You can buy a dual band lnb for c/ku have two i use now .The problem with the rust is it degrades the signal as the dish is not parabolic any more
    Thanks for the answer
    First - put the rusty one in the tip.
    second -- Bought a combined one on the net from Satplus in Victoria his last one will fit it soon to my 2.3 meter dish, but no instructions.
    Now what to do, 2 photos in the internet show 2 ways of hooking up.
    one is loop the ku to the second post on the c band lnb and one cable to the reciever.
    also another shows the ku and c connected the either a disec swicth or a 22hz swich (i can't spell)
    Which did you use?

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    well depends on the dish if you dump it or not , whether you have a relationship with it have you ever slept with it and had sexual relation with it , lol yep dump ???secondly I have used both separate receivers two coax ,diseq switch, normally the 22khz is the easiest but some lnbs use that for lo adjustments or vert/hoz switching I tend to favour diseq sw at the lnb. Don't think you need instructions , you got austech lol. I have never used the loop arrangement as you can get " shadows" or other nasties from the lo of the c bander ok next question
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