36" Ku dish setup problems

[rrob311]

I bought a pair of 1m ku offset dishes last summer locally for a good deal. I also got a couple of Fortec Lnbs. When I initially setup the 1st dish I could not get enough depth travel with that lnb so I couldn't get any signal. I put my trusty old LNB in that has more adjustment and was able to get 70-72% quality on 97w on most of the channels. I left the dish like that for awhile but I just got a triple mount for the dish and I want to utilize my 2 fortec lnb. The center lnb on this setup fits differently on the dish and still seems to have a depth problem. Does anyone have any suggestions on how to get the focal depth proper? I am not sure how to measure it on an offset dish like this. Should I drill holes in the main arm that comes out so I can bring the LNB in? This dish is just one of the cheap 39x36 ones. I have a similar one on my house with a motor and it works great. This one I can't get much out of. I expected a better signal on 97w but could never get more than 72%. I am pretty sure the focal depth was never right but I ran out of adjustment. The Fortec LNB has almost no adjustment for this. I have the 2nd dish still not setup yet and I don't want to put it together until this one works properly. I plan on getting 97w, 87w and maybe 83w if possible with the tri mount.

 

[polgyver]

Did these "good deal" dishes come with original LNB holders (brackets) ? Could it be that this one you are trying to use is a little distorted (bent) ? Did you run a string test to exclude this problem? Can you post some pictures of this dish? I have a few dishes sized 40" x 35" with a name Q-sat, they are relatively big, but they have rather short focal length, appr. 22" from LNB face to the "centre" (a place roughly equally distanced from the 4 mounting bolts). I could not get 97 and 101 with regular LNB's (2" face dia) unless I would substantially "shave" them. Other dish, 36" x 33", despite being smaller, allowed for it, as it has 24" focal length.

 

[rrob311]

I can post pics hopefully monday. The original lnb holder worked for 97w but I am pretty sure the focal depth was off because the q jumped big time bringing the lnb in as far as it would go. It seemed that I could get more but I ran out of room. The fortec lnbs have almost no adjustment. maybe 3/8". I am not sure how to check the measurements on these offset dishes. But the center mount on the tri lnb bracket seems to bring the lnb out further so I would like to be able to set that one properly. The other ones are fully adjustable so once the center one is good I should be able to get those. How far apart should I be able to go for satellites numbers?

this is the ebay item # for the tri bracket I bought:360207724637
and dish:
39 inch by 36 inch Megasat Juggernaut International dish

 

[Keith Brannen]

One way to bring the LNB forward is to get a much longer bolt, and add spacers between the plastic LNB holder and where it attaches to the centre metal post of the new bracket. Depending on the length of the new bolt, you could move it quite a ways closer to the dish. For spacers, I'd use something like thick square metal strips (which would add to the stability of the unit the further out you go).

 

[AcWxRadar]

Rrob311,

You should have better responses than that with this dish. I suspect that there may be an assembly error here.
Take a closer look at the support struts that come in from the sides of the dish for the LNBF support arm.
Where these arms attach to the end of the LNBF support arm, there may be other holes in the arm to attach them.
Also, check the points where these support arms attach to the perimeter of the dish, there may be other mounting holes there, too.

If there is only one set of mounting holes available, at both ends, then you have it assembled as they intended it to be.
However, it doesn't mean that it is correct.

You might try this. Remove the bolts that mount the two outside support arms to the perimeter of the dish. Loosen, but don't remove, the other bolts for the LNBF support arm so that the arm can move freely. Ensure that the main (center support arm) can pivot where it attaches to the bottom of the dish. If it cannot naturally pivot here, this won't work.

Position the two side struts higher (or lower) on the dish perimeter. The same amount each side. Secure them temporarily with duct tape or a light clamp. Then recheck your signal quality readings. This will allow you to adjust the focal distance to some degree, but it will also change the focal point, too.

If you find a "sweet" spot by doing this, you can simply drill two new holes in the rim of the perimeter of the dish and bolt the side support arms to these new holes. Just ensure that you get them aligned perfectly (same height on each side).

You won't be able to move them too far, but you may only need a little bit to get it to work better.

RADAR

 

[FaT Air]

Calculating the focal point of an offset dish: CALCULATING THE FOCAL POINT OF AN OFFSET DISH ANTENNA
Seems I had a link to another, a bit simplified, calculator. Beats me where I lost it(???)
FOUND: the prog here will also calculate FL Parabola Calculator version 2.0

 

[rrob311]

I flipped the LNB holder around so I could lower it some. I locked 91w and I am getting 70-72%q on the abc news channels.(same quality I had on 97w before I switched the mounts) I am having trouble finding birds because the DBS satellites are so powerful. I think I am going to buy a satellite finder. Its difficult for me to find Ku with the analog meter. I was looking at a satlink.

 

[Othea]

The focal depth on my brand new WS9036 was about a half an inch off (that was a couple of years ago), so I just bent the support arms slightly and that solved the problem. There were no "extra holes" to make an adjustment. If I'm not mistaken, the dealer website galaxy has since then corrected the description of the proper focal depth.

Maybe this will help. It's a great dish when properly "adjusted."