Fat Air, more info required

[Inno]

I just saw the picture you posted on another thread regarding the Ku dish you attached to a C-Band and it looks very interesting to me. Certainly would be easier than having separate positioners etc. for both and being as how I already have a 10' dish that tracks the arc perfectly, it wouldn't be much work to add it. How well does it work and how well does it track the arc? I guess the biggest thing would be to mount it rigid enough so it is pointing at the same satellite as the C-Band dish is.
Is this a permanent setup or was it more of an experiment?

 

[FaT Air]

How I made a C band Bud work on Ku.

Well, I thought it would be temporary, but it works so well it's now permanent. It's only a 30 inch Channel Master but does a good job. Tracks just like the BUD- perfect. But being only a 30 inch, there's a couple of satellites and TP's it has trouble with. I chose this for weight considerations (my 1.2m CM's would be too heavy) But I'd bet the metal 36 inch dishes would be llighter. My dish is 100% steel, including the mesh. You'd have to determine if an aluminum dish will handle the weight. (Maybe a couple of guy wires fron the lip to the center of the dish??) My design goal was to have as little of the BUD shaded by the Ku dish as possible. Using the sun, and the shadow of the Ku, looks to be less that 1 sq ft. It's mounted with a large "barn door" hinge. One side square with holes, the other side a large triangle with holes, (the dish side) I aimed at a sat with C and Ku with the BUD, then tweaked the Ku on. Turnbuckle elevation, spring and small turnbuckle on edge of dish for Az. Then tightened the bolts holding the hinge to the lip. (there's some slop in that hinge) I hope the pictures are self explanatory. The first picture shows a zip tie on the edge of the Ku- been replaced with a small turnbuckle, and a spring on the opposite side.

 

[Inno]

Thanks for the details. I have a couple of 30" Star Choice dishes and a Channel Master oval (can't remember the model). I think the 1m might be overkill. My dish is a Orbitron 10'. That idea just makes so darned much sense to me I don't know why I never thought of it!I've been wanting a motorized Ku setup for a while but didn't want to spring for a positioner. Perhaps I can build a mount that will distribute the weight more evenly. My biggest concern is the extra weight will pull the 10 footer out of alignment. I don't think a little bit of overlap will drop the C-Band signal in a significant way as most of my satellites have quality numbers over 80, some as high as 99 on the Pansat.

 

[FaT Air]

I did it because the mesh on my BUD didn't work that well on Ku and also didn't want to spring for a positioner. The .7m CM really outperforms my BUD. Didn't know how much Ku I was missing.(well, yeah, I knew, just didn't want to admit) And moving the fixed Ku's around got to be too much. Sill have 3 fixed, besides the Ku on the BUD. (30°W,(that 1.2 on it's side) 125°W, and another, usually on 103°W*)
I don't think it would pull it out of alignment, but rather warp the dish. But maybe a couple of guy wires from the point the Ku dish attaches on the lip to the center of the dish, or to the dish/ring mounts. Another thought I had was a strut under the dish from the mount ring to the lip. Or both, strut and guys. I've thought that with a light weight dish, the foot of the mount could be mounted inverted under the lip. The dish would be mounted inverted on its mount, with it ending up in about the same place, or below, the lip of the dish. The Ku dish would end up in the normal position, lnb arm on the bottom. I brainstormed this for about 4 months, and fashioned it up as soon as the weather allowed. BTW, where my Ku is mounted is a double rib as that's where 2 panels bolt together. And again, all steel.
*103°W I have a feeling the skew is going to be normal, not 21° off, when SES 3 arrives.

 

[Inno]

I have never tried my BUD on Ku band for a few reasons. One, because I don't think it's "perfect" enough for Ku and two because I have my doubts about the mesh size and three because I have a voltage controlled LNBF on the BUD and I have not run a wire for a polarotor and the only C/Ku feedhorn I have requires a polarotor.

I think I'm going to give this a try. I have nothing to loose and lot to gain! Still looking for 30°W but that is going to wait 'till the leaves fall and after the solar outage occurs so I can pinpoint it.

 

[Dishman Dan]

Fat Air's design is simpler than the "totem pole" idea I dreamed but never tried...

and the main thing is his works!!!

 

[skysurfer]

interesting design. I think if I were to do it, I'd put brackets on my quad supports and mount the dish to that so the weight of the small ku dish gets distributed onto the quad leg supports and doesn't de-form the c-band dish parabola. The c-band dish would only get signal blockage from straight on signals and from an area about the size of the ku-band dish. I'd be surprised if that was more than about 10-15% the surface area of the 10' dish so it might not make much performance difference for most signals,