Dish Specs, Trust But Verify!

Discussion in 'C-BAND Satellite Discussion' started by bpalone, Mar 21, 2017.

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  1. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    Purchased a new 10 footer from Tek2000 to replace my 8 footer. The weather improved to a point that I decided to go ahead and do the install. The install went as expected, up until the point and aim portion.

    My due south is 105W and only has S2 signals. Couldn't raise a thing, moved to 107.3W, was barely able to raise some S signals. After 4.5 days of checking rechecking and replacing components I came to the point of the only thing I hadn't checked was their numbers.

    So, strung string again (had done a string test) and measured the depth of the dish and diameter. Then doing the math, found that the focal point was 43.14 inches not the 48.5 inches all of their documents state. Had to do my own math to approximate where to mount the support rods, as their support would only state that the focal point is 48.5 inches.

    Moved the rods to a point close to what I calculated (was off) and moved the scalar and LNBF much closer to the correct point over the dish. The results were great, was able to check my tracking of the arc and button up to wait for another round of decent weather. Need to adjust things to get scalar and LNBF just a bit higher. Will shim the rods higher when I get a nice day, which will get me to the point I need to be at. That should give me a bit more Q on the weaker signals.

    MORAL OF THE STORY, trust but verify. You should take the time to check the focal length yourself. It only takes a few minutes and can save days of frustration. This is true whether you are rescuing an older BUD or setting up a new one.
     
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  2. waylew

    waylew SatelliteGuys Pro

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    I seem to recall it mentioned here somewhere that there are 2 different sets of arms for those dishes and they need to be attached in different places.
     
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  3. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    Yes, that is the case, but supposedly all have a focal length of 48.5 inches. They even have a sheet that was placed in the hardware box telling about the different rod lengths and clearly states that the focal is 48.5 inches for their 10 footers. My problem was that I wanted to believe their data. But, the tape measure and math proved otherwise. Just wished I had found it earlier.
     
  4. hank123

    hank123 COLORADO CONNOISSEUR BUD HUNTER Lifetime Supporter

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    Post some satellite porn.

    How does the back assembly seem to be on this dish? Will she hold up? Your not to far north of me and I know the wind blows up there.
     
  5. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    They have beefed up their mounting. I can't compare with an old version of their 10 foot mount, but can their old 8 foot mount. It is better and only time will tell. I am in a place where somewhat sheltered from the heavy winds. The pipe portion I had another one built to fit my existing pole and it is heavier than what they ship.

    Running a camera wasn't one of my priorities while fighting my issue. In fact, zero pictures were taken. Being as how everyone really, really like pictures, I will get some. It may be a bit, or maybe even as early as today. Will make point of getting decent picture of frame, etc.
     
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  6. Arion

    Arion SatelliteGuys Pro

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    This is good to know. I intend to get out of their 10' packages in a month or so and it's a concern of mine that since these dishes are made in China and I'm sure the guy at Tek doesn't speak or read Mandarin, that some of the instructions translated into English might not be accurate. Your experience here may save people following you a lot of trouble so thanks for the info. Overall are you satisfied with the build construction considering what you paid for it?? Also, did you source your own mounting pole or get one of theirs? And if one of theirs does it seem adequate?
     
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  7. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    I am pleased, so far. Aside, from the wrong focal point issue. Doing the string test, they touched just as they are supposed to. As I stated above, I had a new pole mount portion made to fit my existing pole, that ran the cost up another $300. But, my back thanked me for not having to dig up and plant another pole. I would recommend that you source your own pole, as I would guess that their poles are probably marginal. That is a guess, so take it for what it is worth.

    Who knows, why my dish isn't the same as what they claim all of them to be. It could of been that while loading containers in China, that someone else's dish got mixed into Tek2000's. I don't know and at this point I don't really care. I got to the bottom of the issue and have a working 10 dish, now. I'm pleased with the performance I have seen so far. Just don't expect to get a Mercedes for a Yugo price.
     
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  8. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    OK, here are some pictures. The first two are showing the change in Q after the adjustment of the feed support arms. I apologize for the flash glare, but had to use it because of a window behind me.

    The second two show how far I had to move the LNBF support arm to get equipment into the focal point correctly. The second one displays some of my handy work, er, well maybe I should say shows the Farmer John, in me. :) The longer bolts I bought were, well... quite long enough.
     

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  9. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    More Pictures of the dish and mount.
     

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  10. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    Got to thinking about all the pictures. Since I had a custom made pole top/saddle made and pictured above, that I thought maybe I should show the pole top/saddle sent from Tek2000. So, here you go.
     

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  11. iBoston

    iBoston SatelliteGuys Pro

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    These are really inferior. Strong winds will tear the welds right off! - I speak from Experience. Your custom work looks GOOD.
     
  12. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    Thanks. The very reason, I figured I had better post pictures of the stuff provided by Tek2000. My goal with the custom one, was to fit the pole I had set. It also benefited from being made from heavier iron.
     
  13. mkv7196

    mkv7196 Well-Known SatelliteGuys Member

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    That's a huge difference between the lnb rod mounting points. Maybe they sent you the wrong sized lnb rods? Can you measure the length of your lnb rods?
     
  14. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    The rods were 59 inches. The measurement and math do not lie. Here are the measurements: Edge of Reflective surface to Edge of Reflective surface -- 117.5 inches

    Depth at center, to the plate -- 19.5 inches to that add 0.5 inches for the plate, so depth is 20 inches.

    Those numbers yield a focal length of 43.14 inches, rather than their many places stated 48.5 inches. Also yields a F/D of 0.367 rather than their stated 0.4.

    Prior to setting at the appropriate focal point, could not lock a single S2 signal. After, just getting in neighborhood was knocking down the S2's with ease. After adjusting to proper focal point (not tweaked, just at measured focal point) am getting the maximum I have seen on my A3 for Q on many of the channels. So, again, I would have to say that the tape and math are correct.
     
  15. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    Finally took time and made a copy of the insert they send in the hardware box and scanned that into a PDF. Quality is not the best, as the original was beat up quite a bit in transit. It recites the support rod lengths and focal points of the different dishes.
     

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  16. zack

    zack SatelliteGuys Family

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  17. bpalone

    bpalone Topic Starter SatelliteGuys Pro Pub Member / Supporter

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    Will respond no further. But, suggest anyone questioning my measurement and calculations, do some searching on finding the focal point for a parabolic reflector.

    Nothing more to say.
     
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  18. a33

    a33 SatelliteGuys Pro

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    Well, it wouldn't be the first time that a manufacturer or vendor gives wrong specs. :rolleyes:

    And I don't understand the reasoning tek2000 gives:
    "With reference to the diagram below, the correct focal length is the distance from p to the parabola vertex v. It is NOT the distance from p to the centre disc (which in all likelihood he was measuring). You have to add an additional 2 inches from the disc to the vertex."

    Adding 2 inches also to the depth of 20 inches measured by bpalone gives 22 inches, even gives a focal length of 39.22 inch. Nowhere near the claimed 48.5. So that reasoning doesn't add up.
    If he meant substracting ('adding to the other side of the disc surface'?), that would give 47.94 as focal length; that would be nearer, but still not 48.5
    But what is exactly the position and curvature of this central disc? Is it really very different from the normal parabolic form, as tek2000 claims? He doesn't give his own measurements.
    So the reasoning in his post I cannot follow.... Something wrong with me or with my reasoning?

    For now I believe the calculation of bpalone, and the improvements he got by the alteration of the LNB position.
    'Trust but verify'!

    greetz,
    A33
     
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  19. armadillo_115

    armadillo_115 SatelliteGuys Pro

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    A33... I figured it the same as you and bpalone... two days ago. I have to remove my socks to count beyond ten though. :oops:

    Dish would need to be several inches wider... or depth less... or a combination to get the stated Focal Length. I never bother to figure the FD after that.

    Maybe they forgot to convert the Canadian Inch to the American Inch. :facepalm
     
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  20. zack

    zack SatelliteGuys Family

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    I never liked math, just saw that on a different site and just passed it along!
     
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