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Thread: cku feedhorn on a 3.7metre mesh dish

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    Exclamation cku feedhorn on a 3.7metre mesh dish

    hi everyone, i have a octagon 518 satellite receiver i have 2 ku dishes a 90cm on d2 at 90cm on c1 plus my 3.7metre running into a 4 way diseq 1.2 switch .i was wondering if the c ku feedhorn still have the same problem like the inacuracy a mesh dish is with a ku feedhorn on it . i look at the specs on my dish its rated at 65db for ku band and my cband is only rated at 50degrees .i was wondering does the mesh dish still have the trouble with ku band signals like when you go from 1 satellite to the other on a c ku combined feed the dish needs peaking again also there is a small loss on the cband portion of 3.7metre orbitron which my dish is!! also if i can get adl feedhorns which i can would it be better running a skew as you can peak the dish to the max using a skew which my dish has but its not hooked up but it can be if i got a adl 400 or similar or a chapparel cband feedhorn ok, thanks hamguy2 nsw



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    Never having played with a mesh, I always thought they werent optimul for Ku band signals as the mesh wasnt spaced correctly to reflect the Ku wavelegth.
    ie that a mesh was like a sieve where Ku was concerned.
    I must admit I also thought a 'solid' wasnt good for C band and the C band LNB had to be on a tripod in the prime focal postion untill I got a Prodeline solid that is an Offset for both Ku and C band.
    I understand now that to begin with most C band signals were a lot weaker than they are now and because of this they needed a large reflective surface area which if they were a 'solid' structure instead of Mesh, they are very heavy and need substanial mounting stuctures to carry them as well as reducing the effects of wind loading.
    A few years ago in the old forums, there were many postings of suggested ways of 'lining' Mesh dish's to improve their Ku receptability.

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    Smile i reckon a skew introduction would be better

    i might have to go to a skew control bcz these cheap cband lnbfs work ok but you cant optimize them on every satellite youve got to compromise your good signals atleast with a skew you can get them all ,un lesws you pay between $1000 to $5000 aus for a comercial 1 ,tyhanks hamguy2 nsw

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    Just try it hamguy.
    A mate of mine runs similar and has pretty good results.
    Your mesh type will influence your reception but the size of your dish will make up for that.

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    If the holes in the mesh are small enough not to let the KU wave pass straight through there will be no problems.
    The box that the dish came in should mention the KU gain telling you its good for KU.

    If your dish needs a different position to lock KU signals just rename sats as C band and KU ie asiasat4C, asiasat4 KU with their own positions.

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    Quote Originally Posted by Godzilla View Post
    If the holes in the mesh are small enough not to let the KU wave pass straight through there will be no problems.
    If memory serves me correctly, the holes have to be less than 2mm and as a rule there will still be a bit of signal loss when receiving KU on a mesh. A solid dish may have a 5% to 10% gain or more over a mesh dish.

    UFO

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    3.7m mesh, where Ku rated - like Hamguy's Orbitron brand yard mount are just fine for C/Ku. (Popular OS for RX of C1/D3).

    Messing-about the install is needed to optimise, I think Ham's, at the moment, using a combined C/Ku LNB - such product I recall use a 22Khz switch internally to switch bands.

    When saving a satellite store position to motor control menu on a decoder under this system, one often needs to save TWO positions per satellite; one for C, one for Ku, as often the LNBF 'target' is not 100% focused.

    Ham's now considering ADL feedhorn systems, bear in mind too some of these need power> additional cabling required, I understand that after install, one 'peaks' for quality each time again. BUT I've not gotten around to going this far, yet. (Being eliminating debt - GFC, this year, but will bounce back early next to go down the same path and new toys).

    So, anyone else here with experience with feedhorn type installs?


    Hamguy - Any reason why you would not simply run ONE 90cm Ku with a multi-LNB holder for RX of D2, C1-D3, D1, even IS8? Dish size is fine for such a job, AND keeps things tidy:-)
    Last edited by Keepleft; 04-10-09 at 10:41 AM.
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    You're right Keepleft.
    I used to have one of these dual band LNB's and ended up giving it away.
    Since both probes are mounted fixed in the throat and are not individually adjustable it will always be a compromise in regards to skew. And furthermore a compromise in focal point aswell. It's impossible to have the KU probes AND the C probes sitting at the same focal distance so again it will always be a compromise.
    Nevertheless it should still be fine for strong signals.

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    Smile ku on mesh dish

    hi thanks for the reply i have enough cables coming in here now with stuff maybe on the bigger dish maybe i might get some other ku beams on pas8 maybe or asiasat5 etc who knows thats why i want to try with a skew etc and experiment i knew i should have put in a 5 to 6 metre dish ,thanks hamguy2 nsw

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