1.2M offset Flat Vs Stacked Cone Scalar
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Stacked cone Scalar
Nice job on construction of the Scalar.
I used the same aluminum flashing and cut a strip 1/2" by 11" and wound that around the Ku section at the Scalar. It works really good and on the DMX741 puts the Ku/C at same focal distance. I'm very happy yet today with the Ku/C performance and hope you have the same success.
I just finished testing the BSC621 with the 1/2" spacer and find that it should be 5/8" on this LNBF for optimum f/d match. But the BSC621 just can't perform as well as the DMX741 on a small dish. For a bud it makes little diff.
Nice job on construction of the Scalar.
I used the same aluminum flashing and cut a strip 1/2" by 11" and wound that around the Ku section at the Scalar. It works really good and on the DMX741 puts the Ku/C at same focal distance. I'm very happy yet today with the Ku/C performance and hope you have the same success.
I just finished testing the BSC621 with the 1/2" spacer and find that it should be 5/8" on this LNBF for optimum f/d match. But the BSC621 just can't perform as well as the DMX741 on a small dish. For a bud it makes little diff.
This is interesting. I hope the manufactures of DMX741U C\KU would apply this modification to their next generation of DMX741U.
Is this modification only necessary for offset dishes? I wonder how well the Ku side works on prime focus dishes.
DMX741 mod details
Minimo first posted this mod and it was on a 6' PF dish.
Here are pics with mod details to work from. I don't recall but the screws are either M2 or M3 by 3/4".
He gets credit for this improvement, I just confirmed his work on PF and Offset dishes.
Minimo first posted this mod and it was on a 6' PF dish.
Here are pics with mod details to work from. I don't recall but the screws are either M2 or M3 by 3/4".
He gets credit for this improvement, I just confirmed his work on PF and Offset dishes.
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Anyone tried replacing the single KU side on the C/KU combo with a regular Dual-ouput LNB using this method?
You bring up an interesting idea. Seems like that could work. Although, the scalar ring for the Ku LNB within the combo is flat, not conical like most stand alone Ku LNBs. You'd probably have to find a feed horn. Maybe a feedhorn like the one I have pictured below. It may not matter what the scalar rings look like.
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Wow! Great pictures, ADAM. I added my last post without noticing these. This will certainly help when I receive my DMX-741u on Monday!
There might be a little business venture for someone who buy's these bulk and then modifies and resells them. I'd buy 10 at a time, do the mods and then slap them on a dish to confirm they are working up to spec and then resell them at a $40 to $50 premium. I'd bet you would get some business. A lot of people are reticent to go into the guts of an lnb like that even though it's not too terribly hard.
I received the DMX-741u and modified the space between the C-band feedhorn and the Ku LNB. Unfortunately, my results weren't that great. I get about a 60 quality on CBS Newspath with the mod. With my Invacom Ku LNB, I get up into the 80s. With the 741, I had the highest ku quality when I hand held the Ku LNB about 3/4 inch away from the C-band feedhorn. I wrapped the exposed area with 3/4 inch flashing. The problem is that the 741 has to be set so far back that the face is flush with the plastic LNB bracket. In other words, I lose any room for placing the C-band scalar rings onto the 741. This kills my C-band reception. I might try to place the LNB support arms out further somehow. I'm certainly not giving up, though. If FTA has taught me anything, it is to be patient. That, and there is usually a solution to just about any problem. You just have to think about it long enough.
Longer lnb arm
Yep, in another thread I posted how I had made the LNBF arm for the GeoSatPro 1.2 m dish about 1 1/2" longer. If you do this then you may want to try the 1/2" spacer again. You also need to adjust the dish elevation for the new LNBF position.
Yep, in another thread I posted how I had made the LNBF arm for the GeoSatPro 1.2 m dish about 1 1/2" longer. If you do this then you may want to try the 1/2" spacer again. You also need to adjust the dish elevation for the new LNBF position.
DMX-741 not as good as seperate Ku LNBF
Hope I didn't give you the wrong idea. The DMX-741 Ku section is not as good as a stand alone Ku LNBF. I was just happy to get both sections to tune on my dish. (results will vary with dishes and hobbyist)
Example: Ku on 76cm dish on RTV with Coolsat 6000P SQ = 92 on 1.2 M dish with DMX-741 70 to 87 SQ.
What I like is I get very good 91W C and 99W C and still get all the Ku I like to watch on the same dish.
The DMX-741 was designed to work on a large BUD and a few here are doing that.
Hope I didn't give you the wrong idea. The DMX-741 Ku section is not as good as a stand alone Ku LNBF. I was just happy to get both sections to tune on my dish. (results will vary with dishes and hobbyist)
Example: Ku on 76cm dish on RTV with Coolsat 6000P SQ = 92 on 1.2 M dish with DMX-741 70 to 87 SQ.
What I like is I get very good 91W C and 99W C and still get all the Ku I like to watch on the same dish.
The DMX-741 was designed to work on a large BUD and a few here are doing that.
Fortec f/d
I remeasured the distance from the plastic LNBF cover to the center of the dish between the four bolts and it is set at 31 3/8". Your dish has a shorter f/d then mine. If you re-read my first post here you'll see that the f/d is different.
I remeasured the distance from the plastic LNBF cover to the center of the dish between the four bolts and it is set at 31 3/8". Your dish has a shorter f/d then mine. If you re-read my first post here you'll see that the f/d is different.
You didn't give me the wrong idea. This hobby is very experimental. 
I measured from the center of the four bolts to the LNB holder and it is 34 3/4 inches. Would it still make sense to lengthen the LNB support arms?
I measured from the center of the four bolts to the LNB holder and it is 34 3/4 inches. Would it still make sense to lengthen the LNB support arms?
You didn't give me the wrong idea. This hobby is very experimental.
I measured from the center of the four bolts to the LNB holder and it is 34 3/4 inches. Would it still make sense to lengthen the LNB support arms?
Yes, so that the black plastic LNBF bracket is in the center of travel of the LNBF. Your dish has a different geometetry then mine and once you find the f/d that gives best operation for the DMX-741 on both bands, then others using this dish will be able to follow your findings.
Nice job guys... Do you guys know the formula of creating this kind of scalar ? coz of my friend says there is a formula for creating scalerring so am looking for more info about it
I think their "formula" = "trial" + "error" and seems to be working. I have a DMX-741 and read about bent probes...to straighten them before putting it on the dish. I hope I got them straight enough and inline with each other...C=Ku. I am curious how much this 1/2 spacer affects a BUD?
I am very interested in this FD thing.
Very good work.
I am very interested in this FD thing.
Very good work.
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