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Distance of triple LNB to 18x20 Dish?


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17 replies to this topic

#1 OFFLINE   beachlover

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Posted 16 April 2010 - 07:04 AM

I'm making trying to use a dish that doesn't have the proper arm, can anyone give me some measurements as to where the triple lnb should be in relation to the dish? Maybe the measurement from the plastic middle lnb to the center of dish? to the bottom of dish? and to the top of the dish? With those three measurements I should be able to make it work.

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#2 OFFLINE   boba

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Posted 16 April 2010 - 08:05 AM

Good luck you need the focal point of the dish you are using, not the dimensions of the phase 3 dish.

#3 OFFLINE   beachlover

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Posted 16 April 2010 - 08:20 AM

Good luck you need the focal point of the dish you are using, not the dimensions of the phase 3 dish.


I thought that's what i'm asking for.... in laymans terms?

#4 ONLINE   carl6

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Posted 16 April 2010 - 09:01 AM

I thought that's what i'm asking for.... in laymans terms?


In laymans terms, the size and shape of the dish determines the distance the LNB needs to be from the reflector. Unless the dish you are trying to use is the exact size and shape of the 3 LNB dish, the focal point won't be the same.

So any measurement of any other dish is going to be irrelevant.

#5 OFFLINE   beachlover

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Posted 16 April 2010 - 09:08 AM

In laymans terms, the size and shape of the dish determines the distance the LNB needs to be from the reflector. Unless the dish you are trying to use is the exact size and shape of the 3 LNB dish, the focal point won't be the same.

So any measurement of any other dish is going to be irrelevant.


That's why I wrote 18x20 dish in title.....so it's the same, but the arm is not....

#6 OFFLINE   curt8403

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Posted 16 April 2010 - 10:24 AM

That's why I wrote 18x20 dish in title.....so it's the same, but the arm is not....


So, you are saying you have an 18 X 20 dish, but the arm is broken, or missing, or maybe a different mounting device (Like from a different dish)

why not just order a dish upgrade from directv?
I am no longer connected with Directv or any other satellite provider

#7 OFFLINE   beachlover

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Posted 16 April 2010 - 11:05 AM

So, you are saying you have an 18 X 20 dish, but the arm is broken, or missing, or maybe a different mounting device (Like from a different dish)

why not just order a dish upgrade from directv?


I have my reasons but will not discuss them here

#8 OFFLINE   litzdog911

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Posted 16 April 2010 - 11:43 AM

We can't really help you if won't disclose your "reasons". What you're trying to do is just about impossible. The dish geometry and LNB type & positions must be closely matched for proper reception of multiple satellites with one dish. And with the newer mix of Ka-band and Ku-band satellites, it just about impossible to combine multiple dish/LNBs together anymore.
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#9 OFFLINE   curt8403

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Posted 16 April 2010 - 11:55 AM

remember, spraying your dish with PAM will result in rather buggy reception.
I am no longer connected with Directv or any other satellite provider

#10 OFFLINE   Floyd

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Posted 16 April 2010 - 10:11 PM

Jeesh folks, it's a fairly simple question, with a fairly simple answer.

from top front edge of dish to middle of middle lnb = 18"
from center of top two bolts to middle of middle lnb = 13-1/4"
from front of lower edge to middle of middle lnb = 12"
Dish is 18" H x 20-1/2" W

#11 OFFLINE   beachlover

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Posted 17 April 2010 - 05:16 AM

Jeesh folks, it's a fairly simple question, with a fairly simple answer.

from top front edge of dish to middle of middle lnb = 18"
from center of top two bolts to middle of middle lnb = 13-1/4"
from front of lower edge to middle of middle lnb = 12"
Dish is 18" H x 20-1/2" W

you have restored my faith in humanity Thankyou

#12 OFFLINE   JJJBBB

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Posted 17 April 2010 - 06:44 AM

Kinda tough getting that out wasn't it? Why didn't anyone else just help him? Sorry dude wish I saw this thread sooner.
NATIONAL HD... I want it all, I want it now. I've been really patient. (Will dance for more HD :stickman:)

#13 OFFLINE   boba

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Posted 17 April 2010 - 07:19 AM

Kinda tough getting that out wasn't it? Why didn't anyone else just help him? Sorry dude wish I saw this thread sooner.


Nobody helped him, he was just given useless information.:nono2:

#14 OFFLINE   joe diamond

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Posted 17 April 2010 - 07:41 AM

you have restored my faith in humanity Thankyou


Beachlover,

It is not as simple as you think. That dish is a parabolic reflector...like the inside of a spotlight. You need the formula for the inside curve of the dish. Then you have to find the focal point of that dish. Outside dimensions alone will not give you this.

What you want to do is possible but beyond the skills of most. After you have the dish correctly pointed (az, el & tilt) at the satellite 23,000 miles out you have to correctly position the LNB to intercept the signal at the focal point of the dish.

It is easier to acquire a dish outside the Directv or DISH system. Retailers like Solid Signal will have what you want and ship the same day.

Report success.

Joe

#15 OFFLINE   Floyd

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Posted 17 April 2010 - 10:53 PM

There seems to be a reading comprehension failure here.

#16 OFFLINE   cartrivision

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Posted 17 April 2010 - 11:33 PM

There seems to be a reading comprehension failure here.


There sure does. At least the OP finally got the information that he needed (from you Floyd).... now he just needs to ignore all the people who are trying to "help" him by giving out bad information based on their misunderstanding of what he needed.

#17 OFFLINE   Rosco

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Posted 18 April 2010 - 12:02 AM

Don't know if this is what you are wanting to do or just fabricating one from scratch, but I've done one of these phase III dishes with the newer SL3 lnb, as the post say, better signal when you grind off the rib on the bottom of the lnb and re-drill the lnb mounting holes in the arm.
http://www.dbstalk.c...=phase III dish

#18 OFFLINE   JJJBBB

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Posted 18 April 2010 - 07:05 AM

There seems to be a reading comprehension failure here.


fgjkhj'; hklf'' ... !

:D
NATIONAL HD... I want it all, I want it now. I've been really patient. (Will dance for more HD :stickman:)




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