MULTI-SATELLITE SIGNAL ACQUISITION

[bygfoot]

OK...

I have a dish 33X30 paired with 2XDual LNB on a Y yoke.

Trying to acquire 82 (nimiq 4) + 91 (Nimiq 1,3)

I seem to do OK with elevation and skew because I can find a happy medium whereby if I rotate the dish I can get OK signal on either one.

The problem is that I do have to rotate it between them.

I am not certain that the yoke (or LNB's, although they are standard lnb's) are meant for this dish... the yoke was taken from a different smaller dish but seemed to measure close to the same.

Could these results indicate that the lnb's are sitting too close (or too far) from the dish itself.

Any help appreciated, just a novice trying to figure things out.

 

[Slartibartfarst]

The standard Dish for Bell TV is a 20" slightly eliptical Dish. The exact same as the Dish 500, used by Dishnetwork.

I always advise on setting the skew based on the data for your location, then forget that part, do not touch again. Then connect a solid line (no switch etc) from the 91 LNBF, right back into the receiver. Peak the signal. Then add the second LNBF and switch's. Now run a check switch, you should see both birds.

 

[bygfoot]

well.....

The problem with this is that I had to purchase a large dish because I am far enough south to be doubtful of the ability to get good signal from bell 82 (nimiq 4)

second problem is that the dish cam with a "yoke" that did not fit my existing LNB's, so I had to improvise by substituting my previous y style yoke for 2 lnb... even though the length measurements etc. seemed the same, I have no way of knowing for certain if it holds the lnb's at exactly the right angle\distance etc.

Thus the question... could my current aiming attempt results be caused by the lnb's being to far or too close to the dish because they are different somehow than the intended lnb's might be.

I guess more specifically... what kind of symptoms might one see if the lnb's were incorrect distance from the surface of the dish.

 

[Slartibartfarst]

what kind of symptoms might one see if the lnb's were incorrect distance from the surface of the dish.

No Signal.

A std Dish should get you 91 degrees. Then use the second one for 82, abandoning the "Y" yolk.

 

[bygfoot]

So you are saying, give up on the idea of getting them both on one dish, focus on the big dish for Nimiq 4... then use an additional standard dish for 91 ?

makes sense I guess... just a buttload of hardware for two sats.
Of course watching HD Hockey night in canada during the playoffs would be worth it.

Still curious about what kind of signal issues might be seen with slight inconsistancy in the position of the LNB, would it always be just "No Signal" ?

 

[Mr Tony]

So you are saying, give up on the idea of getting them both on one dish, focus on the big dish for Nimiq 4... then use an additional standard dish for 91 ?

yep

makes sense I guess... just a buttload of hardware for two sats.
Of course watching HD Hockey night in canada during the playoffs would be worth it.

I have 2 fixed dishes for Starchoice and one receiver....2 37x27 dishes

Still curious about what kind of signal issues might be seen with slight inconsistancy in the position of the LNB, would it always be just "No Signal" ?

low or no signal. If the LNB cant collect the correct amount of signal from the satellite you get no picture. With a larger dish the LNB's are farther apart then a traditional 20" dish. The Y adapter for that is for the correct focal length of a 20" dish

I use to use a 24" dish in Minnesota for 91/82 and the gap between the LNB was about an inch....on a 20" dish the LNB's touch

 

[OnlineLC]

I use a Winegard 76 cms and modified things to get both 91 and 82.

I used an old LNBF arm from my old 18 cms dish that I got with my 4700 back in 99 and sawed it to about 10 inches in length and mounted the LNBF to the end feeding the cables through the inside.

I then mounted it to the existing arm on the 76 cm dish by purchasing a metal bar from Home Depot. The bar was about 4 ft long and maybe 2 inches wide and had holes all along. I then cut them into 4 10 inch lengths and purchased some 2.5 inch bolts with wing nuts. By placing a bar on top and one below straddling both arms I held the 2nd arm in place and had some degree of adjustment of angle etc. I did the same a little lower down to ensure rigidity. Each pair of cross bars were held by 3 bolts.

As 82 is my weakest signal, I aimed the dish for that and then adjusted the 2nd LNBF arm to pull in 91.

I would attach a photo but I am way behind the times and don't have a digital camera.

 

[SJ44]

It would be easier to go with 2 appropriate size dishes.

 

[bygfoot]

This is great info guys, thanks for taking the time so quickly, I am very curious about the arm modification procedure (must be the Red Green show in me).

Is there a formula for calculating Dish size\Lnb arm length\lnb position below dead center\distance of lnb from dish surface.


I also have a great deal of difficulty getting my head around the reflective signal model that predicts dish position in relation to the desired bird(s) and how to visualize that when positioning.

Does anyone know of a good tutorial or pdf somewhere that addresses this?
kind of like a "understanding dish pointing for dummies"