perhaps you are confusing the superdish with the dish 500. the dish 500 is the one with the plastic yoke. the superdish has the lnb assembly bolted directly to the arm and then surrounded with a protective/decorative plastic cover.
Understood, but as I view the pictures I can see the mounting screw where the LNBF is attached after modification. It appears that the LNBF, if mounted directly to the tube, will be set quite a bit forward due to the way the original LNBF is constructed.
i guess i still did not answer your question that i assume is about the dish 500 . yes if you remove the yoke the focal point will be affected and the arm will need to be made longer to compensate for the missing portion provided by the yoke . adding the equivalent length will restore the focal point to its correct value.
Yes I am well aware of the difference the yoke causes with the Dish 500. What I am saying is the pictures imply the Superdish LNBF appears to be a greater length as compared to mounting an LNBF directly to the end of the tube...and it appears that this length is quite substantial. If it is then the same would be required of the Superdish...additional length would be required to bring the feedhorn to the correct focal length.
sorry but our answers seems to have crossed in the time it took me to type the reply. the original lnb is installed in the center position in respect to the dish as is the replacement one. the two lnbs are made differently and this seems to account for the difference. the replacement lnb is recessed under the plastic cover and the original one is not.
I think the pictures in this thread are insufficient to clarify the LNB mounting question.
Hopefully, the one below will help.
Sorry I don't have the name of the SatGuy who posted the good one originally. edit: found a link to where I posted the relevant pictures before.
Without having a SuperDish to play with, it would appear that BobInVa's clever use of the rectangular-based linear LNB is pretty darned swift!
I guess I never looked closely enough at the pictures before to realize it!
And, he winds up with a dual output (which is more desirable to some) for under $20.
Okay, here's the definitive view I was thinking about.
That's the stock 105° LNB at the stock location, without any distraction of the shroud.
Looks to me like a rectangular based LNB would fit into the support arm, and be pretty close to the focal point.
Okay, here's the definitive view I was thinking about.
That's the stock 105° LNB at the stock location, without any distraction of the shroud.
Looks to me like a rectangular based LNB would fit into the support arm, and be pretty close to the focal point.
Yep, I experimented with this and found that the proper focal point for a rectangular tube LNB was indeed to just have the LNB sit at the end of the arm. Just feed two cables up the support arm, and you have a dual LNB solution that looks great. Not too bad at pulling in signal either.
I guess the problem was I couldn't see the second mounting screw on the arm and it appeared the LNBF was being attached to the screw hole seen in pic 1 and that isn't really the end of the arm.
I see.
The white piece is bolted to the metal (screws are hard to see).
Then, that big bolt holds the black LNB holder to the white thing.
Creative.
Below is a drawing I found while wading through the marshes one day.
It shows how to get the original LNB center/height/distance before an LNBectomy, and to verify your new one afterwards.
Should be self explanatory.
The white piece is just 1/4" plastic, used two of the original LNB screws (t8) to mount it. I drilled and tapped it to 1/4-20 for the bolt that holds the black mounting bracket (ebay). The Linear LNB's nose lands right where the old ones did. Makes it easy to fine tune for max Q.
Not too bad at pulling in signal either.
