LNB placement

[Cosmokramer11]

So I have a primestar 84E dish and my lnb is invacom QPH031. No I have read that the 84E should be only used with its original lnb. I do have that lnb it works fine, but it doesnt get all the channels. I know if I use a multi switch I can get both V and H signals. But I just want to use my QPH31. So what I did was I zip tied the QPH31 to the primestar lnb arm. I do get signal but I cannot get any quality. Its too late for me to put on the original lnb back on. So my question is since the QPH31 isnt on the lnb bracket is thats whats giving me my current problem? Other than that my setup is the same.

 

[Anole]

If your QPH-031 is not at the focus, performance of the dish will be degraded.
I assume it's left/right or high/low, relative to the original LNB (or maybe too far away/close to the dish?)

Likewise, the feedhorn/scalar in the QPH-031 is designed for a round dish, and it will not give optimum performance on an elliptical dish.
Doesn't mean it won't work, but it won't be optimal.

edit:
Or, you could graft a 10750 FSS LNB off a DishNetwork SuperDish to your 84e's feedhorn.
That'll give ya both polarities and no switches. Just gotta be able to handle bandstacked.
..or get the Hughes LNB off eBay...
I think the pictures below are courtesy of Tron:

 

[Cosmokramer11]

I dont mind if its not optimal. I just want to get some quality!. Its not left right or high/low. Its actually right where the Primestar lnb arm ends.

 

[Wescopc]

Is the feed-horn of the QHP-031 in the exact same position (up/down left/right) as the original feed horn? That is the focal point of the dish and where I would start trying it. It will never work as well as the original horn that was designed for the Primestar and maybe not at all for weak signals.
Bob

 

[Mr Tony]

The issue is the QPH would sit higher than the "stock" LNB because the throat is bigger. In the past I've gutted the casing right behind the eye of the LNB...but a QPH I'd think twice since they are spendy units

Here was one of my Primestar dishes with a gutted LNB for 74W

 

[Cosmokramer11]

So I just rehooked up the primestar lnb and I got my channels back. So it looks like I have to find another way to mount my QPH31

 

[Anole]

If a 2x4 (or 3x4) multiswitch would solve the problem...
.. I think we've had discussions about finding them cheap.

Also, revisit my post above ...
I spent too long editing in some pictures 'till after you posted, and ya might have missed the comments on alternate LNBs.

Lastly, you might post a picture of your existing LNB/feed, and how you had the QPH-031 mounted.
Unless you just happened to use the wrong outputs, I'm sure a picture will give some hints as to what failed.

 

[guacharaca]

Sometimes even if you get the new lnb in the exact sweet spot, there are more or better scalar rings on the original lnb. I replaced an old Japanese single polarity ku lnb with a new dual polarity (both designed for an offset dish) and the new one could not get the S2 signals that the old lnb could receive. The old lnb was designed for this particular 1.2 meter dish and had the scalar rings that matched the dish. The new lnb was generic for offset dishes. The new one just could not get those difficult to receive signals. Because I wanted the S2 signal of OETA on Verticle, I decided I could live without the horizontal feeds on that satelite and left the original lnb intact.