Focal Distance of a Dish

[chapelrun]

I have this dish and I want to use it for 97W and 101W using a Sadoun KLB LNB (both pictured)

Only problem is the dish did not come with an arm to hold the LNB. I made one that works but I'm not sure I have the focal distance correct.

If someone has this exact dish could you measure from the center of the dish to the center LNB?

 

[turbosat]

What's the size of the dish, I may have an old one like it in my storage area. If it' s about 20" or so I can go look for you. and measure f/d

 

[chapelrun]

YardStick Rules

A quick measurement of the face shows 30" wide and 23" tall.

 

[Tron]

It looks and measures like a Superdish reflector, but usually they are marked with the Superdish logo. Is the mount still attached to the back? That dish is somewhat small for Ku FSS (although it would probably work if you can find the feed support arm)...

 

[chapelrun]

I do have the mount

Yes, I have the mount but I do not have the arm that holds the LNB.

The first arm I made was out of wood but I don't think that will work because its not rigid enough. I might be able to find the right arm or I might bag entire idea and purchase a GloryStar dish with the 4 degree separation.

I think I like the tinkering part of this hobby the most....wife still thinks I'm crazy....but that's OK.

 

[bloomdog]

Click here --> Determining the focal length of a parabolic dish

 

[chapelrun]

I tried that

This formula only works for circular parabolic dishes. My assumption is that the math is more complex for an oval dish, but I'm not sure.

I have guessed that the focal distance is about 20.5" but I think that figure is not quite right.

 

[Hermitman]

If you really want to know the exact location of your focal point, here's a webpage for you. Have fun.

CALCULATING THE FOCAL POINT OF AN OFFSET DISH ANTENNA

 

[olliec420]

Yes, I have the mount but I do not have the arm that holds the LNB.

The first arm I made was out of wood but I don't think that will work because its not rigid enough. I might be able to find the right arm or I might bag entire idea and purchase a GloryStar dish with the 4 degree separation.

I think I like the tinkering part of this hobby the most....wife still thinks I'm crazy....but that's OK.

Hey man, thats a dish 1000 right? i have one of the metal superdishes with no mount on the back but i have the arm that holds the lnb. if you can figure out if it is the same let me know and i can send it to you if you pick up the shipping.

 

[bloomdog]

I have been researching for you and it appears to be a 500 + Dish, described as:

General Information
DISH 500+ allows customers to receive programming from three orbital locations; 118.7°, 119°, and 110° using a dish antenna size similar to SuperDISH (Parts are not interchangeable with other dishes). DISH 500+ will display DBND as the device for 118.7° when a Check Switch test has been run.


Dimensions:

1 5/8" mounting mast
23.8"h x 30.9"w dish face

Standard Configuration:
DISH 500+ includes a Dual Band LNBF and one DP Dual LNBF. All DISH 500+ will need to be installed with a DP 34 switch.
DP Dual Band LNBF for orbital locations; 118.7°, 119°
DP Dual LNBF for orbital location; 110°,

Models 2800, 6000, and 721 may display the 118.7 orbital locations in the Point Dish and Installation Summery screens as “119K".
Others will display the 118.7° orbital locations as "118" in these screens.

* All DISH 500+ will need to be installed with a DP 34 switch or DPP44.

Receivers NOT compatible with DISH 1000: (*no 129/118.7 support)
1000, 2000, 3000, 4000, 5000, JVC-IRR, DISHPlayer 7100/7200

 

[chapelrun]

Thank you

Hey man, thats a dish 1000 right? i have one of the metal superdishes with no mount on the back but i have the arm that holds the lnb. if you can figure out if it is the same let me know and i can send it to you if you pick up the shipping.

Check your PM.

BTW, the Dish I have is 30" x 23" and is a DISH Plus

 

[olliec420]

Check your PM.

BTW, the Dish I have is 30" x 23" and is a DISH Plus

Pics to confirm....

 

[chapelrun]

Two Questions

That looks right, but two questions.

1. What is the size of the DISH in the pic?
2. How long is the LNB arm in the pic?

BTW, I would need the bolts too.

 

[olliec420]

I havnt measured but it is the size a superdish, im sure you can find it on google or something. it looks just like the one you have. i will measure the arm and giving the bolts is no problem. i dont need anything off it, the mounting hardware on the back is gone so im just gonna throw it away. it was a freebie from craigslist and i took the lnbs and dont need the rest.

 

[chapelrun]

OK, Cool!

I think that is the ticket then. I will send another PM right now.

 

[chapelrun]

OK, I finally got back to this

Thank you Ollie for the Super Dish Arm !!! - - - I finally got back to this

OK, I put everything together and mounted this dish on my house to try to get more KU band. Here is my problem.

I still don't have the focal length correct. It is currently 21.5" from the center of the dish to the LNB which I think is too long. The arm that holds the LNB came from "olliec420" (thanks again) and came off an old DISH network Super DISH. My dish is 30 x 23 and is a DISH Plus which is slight smaller than old Super DISH. I think I have the angle of the arm exactly correct but don't yet have the focal length exact yet.

I plan to remove the bolts holding the LNB and temporarily attach it with cable ties and move the LNB up and down the arm until I have get 61.5 signal correctly.

Any thoughts or help - - - my wife now thinks I have completely lost it...dish parts all over the front porch

 

[Larry1]

From the picture, the LNBF seems to be pointing to the top of the dish and not the centre of the dish. Might be different with yours, but with the dishes I have seen (generic and not the Dish Network in question) the LNBF points to the exact centre of the dish. Should be pointing to between the two, left and right, bolts. Is the LNBF's from that dish or are you attaching them from another dish. If they are from that dish that should give you another clue to the arm length.

 

[Pepper]

Some notes about the picture:

1. the pan is from a dish 500 PLUS or dish 1000 PLUS.

2. the arm is, according to who you got it from, from a superdish.

3. the LNBF assembly is a 119/121 from a superdish and not the Sadoun one in the original post. one of the LNBs is DBS (the one that is "straight"), the other is FSS (the one that curves off to the side). Besides that both are bandstacked.

 

[chapelrun]

Fiddle-ing on the roof

I tried to follow "Hermitman" math and could not figure it out. Thus I used the simple formula below and since the dish is oval, I did the formula twice once for 30 and once for 23 and took an average. RAW numbers are 30 x 23 with a depth of 2.5"

Numbers came out 900/40 = 22.5 (for a circular dish of 30")

and 529/40 = 13.225 (for a circular dish of 23")

Average those two and you get 17.86" (My logic here is dizzying)

I guess I'm going to try a focal length of 17.86" but I have to cut some of the arm to make the LNB fit correctly.

Trust me I'm still having fun - - - no really....

 

[Pepper]

Any dish network dealer/installer want to jump in here and give the correct measurements for a DISH PLUS arm? Or somebody that has one want to go outside with a tape measure and let him know?