Results 1 to 14 of 14

Thread: Super Feed Horn Scalar ring

  1. #1
    Junior Member
    Join Date
    Jun 2014
    Posts
    11
    Thanks
    6
    Thanked 14 Times in 3 Posts
    Rep Power
    0
    Reputation
    290

    Default Super Feed Horn Scalar ring

    Hi, I am setting up my mesh c-band dish and are now at the point of alignment. I bought a new LNB & feedhorn scalar ring combo (mediastar sg5150 + superfeedhorn scalar ring) now the problem is that the scalar rings are deeper then the standard scalar ring: 60 mm vs 28 mm.
    The focal point of my dish is 1426 mm and if I understand it correctly that is the measurement from the centre of the dish to the edge of the scalar ring. With the standard scalar ring that works out fine, however with the super scalar ring the support arms seems to be to short as I can't get further then 1416 cm.

    Any input on the right installation of the super scalar ring? does the bottom plate of this scalar ring need to be 32 mm further away from the dish compared to the normal scalar ring?



Look Here ->
  • #2
    Banned

    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,779
    Thanks
    5,562
    Thanked 1,964 Times in 714 Posts
    Rep Power
    0
    Reputation
    35657

    Default

    heres the answer for you , go to the dollar shop buy tiny mirrors for $2 for ten or so take them home to dish and glue them to the outside of the dish mesh once this is done get a sheet of a4 cardboardand hang it on the lnb stays then move the dish directly on the sun so you have a shadow equally on the center of the dish then you can move the holder to get the smallest and brightest light on the card board measure this spot to the center of it and thats where your lnb throat goes you wont have a lot of time as the sun is continuously moving so every 3-4 mins you have to move the dish but its the most accurate way to do it and any distortion in the dish will show up as well so you will end up with a very effective dish good luck

  • The Following User Says Thank You to hinekadon For This Useful Post:

    phri (15-05-21)

  • #3
    Senior Member
    B52's Avatar
    Join Date
    Jan 2008
    Posts
    829
    Thanks
    37
    Thanked 402 Times in 224 Posts
    Rep Power
    367
    Reputation
    7116

    Default

    As showing on the LNB is placed back from the feedhorn edge. You measure 1426 mm from the center of the dish to within 5 mm inside the LNB throat.. On the LNB you'll see marking, should be between 0.36 to 0.38. to the fixing collar.
    Ultimately you'll need to tweak the LNB V/H orientation and focal distance using a satellite meter for the best BER and MER.

  • The Following User Says Thank You to B52 For This Useful Post:

    phri (15-05-21)

  • #4
    Junior Member
    Join Date
    Jun 2014
    Posts
    11
    Thanks
    6
    Thanked 14 Times in 3 Posts
    Rep Power
    0
    Reputation
    290

    Default

    Quote Originally Posted by B52 View Post
    As showing on the LNB is placed back from the feedhorn edge. You measure 1426 mm from the center of the dish to within 5 mm inside the LNB throat.. On the LNB you'll see marking, should be between 0.36 to 0.38. to the fixing collar.
    Ultimately you'll need to tweak the LNB V/H orientation and focal distance using a satellite meter for the best BER and MER.
    I extended the arms on the scalar rings to the maximum, put in the lnbf roughly right, subsequently tweaked with locked signal on c/n ratio. LNBF ended up 10 mm deeper then the front of the scalar rings. So yes that worked out spot on in the focus.

    Would it be better to move the scalar ring a bit closer to the dish, while keeping the lnbf in the focus? ( I am not sure what the scalar rings are doing).

  • #5
    Banned

    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,779
    Thanks
    5,562
    Thanked 1,964 Times in 714 Posts
    Rep Power
    0
    Reputation
    35657

    Default

    the scalar rings keep the signal from being corrupted from bounced signals off other parts of the dish as these are out of sync with the original signal and degrade the primary sig dramatically with larger rings it is imperative to get the distance to the outside diameter of the dish exactly the same , normally measured six times around the dish bit hard to do when its up in the air ? but a bit of string is the easy way if you think about it It always works out exactly to the maths any way you know all that pie type stuff you should have read up on but didnt cos you knew it all lol

  • #6
    Junior Member
    Join Date
    Jun 2014
    Posts
    11
    Thanks
    6
    Thanked 14 Times in 3 Posts
    Rep Power
    0
    Reputation
    290

    Default

    The scalar rings I use from the "superhorn" are differed compared to the standard prime focus as the inner scalar ring is less deep then the outside one, Impact??

    I moved the scalar ring closer to the dish while keeping the lnbf in focus. movement of 20 mm in-out of the scalar ring seems to have little impact on strength & quality of signal, in contradiction of lnbf focus & orientation which is critical.
    The mediastar sg5150 lnbf seems to be good with little interference. If I compare with my 2.3 mesh with old Strong lnbf, lots of interference on strong signals on Intelsat 19.

  • #7
    Banned

    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,779
    Thanks
    5,562
    Thanked 1,964 Times in 714 Posts
    Rep Power
    0
    Reputation
    35657

    Default

    you are dealing with to different things re moving the lnb / scalar rings , lnb is to do with focus of the incoming signal and max input moving scalar rings is to do with rejection of out of phase signals which degrade the input signal by removing these the amplifier only works on the band required and is only presented with that so works better . better to view it as a pipe that goes from your dish to the sat so if its bent all the signal dont reach the lnb ????

  • #8
    Premium Member

    Join Date
    Jan 2008
    Posts
    4,311
    Thanks
    5,982
    Thanked 4,171 Times in 1,771 Posts
    Rep Power
    1348
    Reputation
    50392

    Default

    Quote Originally Posted by hinekadon View Post
    you are dealing with to different things re moving the lnb / scalar rings , lnb is to do with focus of the incoming signal and max input moving scalar rings is to do with rejection of out of phase signals which degrade the input signal by removing these the amplifier only works on the band required and is only presented with that so works better . better to view it as a pipe that goes from your dish to the sat so if its bent all the signal dont reach the lnb ????
    Gosh, I wish that you would punctuate your replies instead of just rambling on in one great rush to get it all out.

    Doing so, would make them far clearer for the reader, particularly for those with little or no knowledge of the subject under discussion.

    Nevertheless, thank you for replying to the OP's question.

  • #9
    Banned

    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,779
    Thanks
    5,562
    Thanked 1,964 Times in 714 Posts
    Rep Power
    0
    Reputation
    35657

    Default

    never been much on punctuation yes I suppose I expect those to know but Im only trying to help get the Idea thru ! most punctuation is done with my hands and it dont show up on screens ?

  • #10
    Banned

    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,779
    Thanks
    5,562
    Thanked 1,964 Times in 714 Posts
    Rep Power
    0
    Reputation
    35657

    Default

    how much of my ramblings helped him ? more to the point ?

  • #11
    Junior Member
    Join Date
    Jun 2014
    Posts
    11
    Thanks
    6
    Thanked 14 Times in 3 Posts
    Rep Power
    0
    Reputation
    290

    Default

    Quote Originally Posted by hinekadon View Post
    how much of my ramblings helped him ? more to the point ?
    It all helps. If I can visualize how it works I can understand what is most critical in the set-up.

    It is important for me as I am close to pixelation on some of the incoming signals, and still missing some of the transponders I am chasing (on telkom4 from melbourne). I already use pro rg11 cabling with proper crimp connectors, tried an inline amp (lots more signal but no quality gain).

    btw I am still puzzled what the best set-up is with these "super" scalar rings.

    With the standard set-up it's strait forward: set front of scalar ring at focus and move lnbf to fb/f ratio, followed with fine tuning best on s/n ratio & quality.

    As I mentioned before this isn't doable with the "super" scalar ring as it's much deeper, therefore the arms can't extend far enough to get 32 mm further to meet that point.
    Last edited by phri; 01-06-21 at 01:04 AM.

  • #12
    Banned

    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,779
    Thanks
    5,562
    Thanked 1,964 Times in 714 Posts
    Rep Power
    0
    Reputation
    35657

    Default

    lets change the view, once the signal is in the feedhorn theres nothing to do ! so getting the desired signal into the throat , true and square to the dish is critical . next is the out ouf band or unwanted signals that get into the throat , this is the area that your supadupa rings work by not allowing the feedhorn to "see" them because the more signals the lnb sees the more it has to work and is amplifying unwanted signals and noise , If it only has to work on the signals you want then it produces more gain for your wanted signals . the reason the standard is "Easy" is because there is no linear rejection . the longer the rings the more rejections so it has to be mounted in a more exact position . if you put those little mirrors on your dish you can see any out of position errors and correct them you will also see any mis-alignment as well ok ?don

  • The Following User Says Thank You to hinekadon For This Useful Post:

    phri (05-06-21)

  • #13
    Junior Member
    Join Date
    Jun 2014
    Posts
    11
    Thanks
    6
    Thanked 14 Times in 3 Posts
    Rep Power
    0
    Reputation
    290

    Default

    Quote Originally Posted by hinekadon View Post
    lets change the view, once the signal is in the feedhorn theres nothing to do ! so getting the desired signal into the throat , true and square to the dish is critical . next is the out ouf band or unwanted signals that get into the throat , this is the area that your supadupa rings work by not allowing the feedhorn to "see" them because the more signals the lnb sees the more it has to work and is amplifying unwanted signals and noise , If it only has to work on the signals you want then it produces more gain for your wanted signals . the reason the standard is "Easy" is because there is no linear rejection . the longer the rings the more rejections so it has to be mounted in a more exact position . if you put those little mirrors on your dish you can see any out of position errors and correct them you will also see any mis-alignment as well ok ?don
    Ok thats clear. I haven't tried the mirrors on the edge yet, as the dish is on a 2.7 meter pole thus the top is high on a 3.7m dish. I might try this on a sunny windfree day this spring. I think tuning is ok for now based on the transponders I receive. btw, I actually just can reach the lnb when I am standing on my A-frame high ladder.

    The modern superdupa scalar rings as well as the normal scalar rings seems to be quite flimsy compared to the scalar rings which were made 20-30 years old. Is there any gain to be expected with the old meaty rings, or is that just old style, none efficient use of material?

  • #14
    Banned

    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,779
    Thanks
    5,562
    Thanked 1,964 Times in 714 Posts
    Rep Power
    0
    Reputation
    35657

    Default

    I can add that the older rings were better because of the effect of the sun and they distorted less on hot/cold days the only disadvantage is the material that was use is a but cruddy and can corrode badly i found to make them last ,I put them in my lathe and spun them to a polish finish then epoxy painted then ! did one in 1985 , its still as good as new , the other secret is to use nickel anti seize on your bolts as its very conductive and they undo readily even in the alli parts . the mirrors can be a great help if the dish is getting a bit old as you can see the distortion from the reflections even a few helps to align it . I have put then on with a long stick and blue tack with rtv on the back of the mirror so long as they are flat on the mesh its all good once they are in place a bit of paper and meths on the stick cleans them up good then a cardboard sheet a4 size will show where each one is pointed and then you get the whole dish being used effectively . the mirrors are only about 25 mm across from the $2 shop easy as pie cheers don

  • The Following User Says Thank You to hinekadon For This Useful Post:

    phri (06-06-21)

  • Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •