Thinking of building a Ku dish from scrap

[. Raine]

Hi Everyone,

Maybe someone's done this already? I have an old polar mount from a C-band dish that I'd gotten years ago. [the dish and a lot of other junk with it, had flown out of the back of a scrapper's truck onto the edge of my property and they never came back for it. The dish itself smashed into pieces but the mount seems unbroken, though the motor housing did break.] I've been cleaning up around my place the last couple of weeks and I came across this polar mount and had the idea of making a Ku dish out of it by welding together a frame and then some panels onto that and then onto the mount. I know I'll need to figure out length and angle of an LNB arm, focal point, but I'm not sure about optimal curvature of the dish, nor diameter. Or whether this would even work or not. What is the optimum diameter for a Ku dish? I suspect the diameter and curvature would depend on one another and that there's a formula for figuring it out, but I don't know what it is. I realize that no one can say one hundred percent whether it would work or not because it depends on my skills. This will probably be a project for next summer if it is doable because right now I'm setting up a C-band dish but if for some reason it's not feasible then I'll probably just stuff the polar mount into some corner of my garage again. If it is at all doable then I'll probably plant a pole for it at the same time as the one for my C-band dish.

 

[northgeorgia]

It's feasible, but a bit frustrating. No experience here, but I'm considering a C-band project myself, since it's MUCH more forgiving than Ku-band as far as imperfections in the dish construction go. Usually better to just find an old dish on Craigslist. Several old threads on this. There is a freeware Parabola calculator program somewhere for download (sorry, I don't know the link). Also check out http://www.vetrun.net/forums/showthread.php?t=1077 and http://www.worldofdth.com/thread-Ma...ellite-dish-antenna-in-less-than-Rs600-Part-1

 

[turbosat]

I don't know about building a dish from parts, I suppose once you get the parabolic shape formed that it could be done. But putting an existing ku dish on a c-band polar mount and making it work-yes, I have done it. Still using the setup today, 3-4yrs later and have not had to adjust a thing. The actuator is getting aged though, lol so it might be the first thing to die off. If you want to build yours that way, I'd say find at least a 1meter dish, should be plenty big enough. It's what I'm using on mine. If I can find that thread here, I think I had some pictures posted when I was in the construction phase. The hardest part of it for me was building enough "tilt" in the attachment of dish to mount, to allow for that extra 22 degrees of downward elevation that ku dishes have. Putting a prime-focus, KU only dish on it would have been cake.

 

[Anole]

Five (?) years ago, a bunch of guys on an Aussie forum made Ku dishes.
I think they said it took about a 5' dish to equal a commercial 3'er, so not real efficient.
Vertun forum
?
?I decided against bothering.

 

[gpflepsen]

I'd make a turntable and spin-cast a perfect parabolic shape. Maybe use that to make a fiberglass layup mold and go into production. Or spend $99 for a geosatpro 90cm dish.

 

[waylew]

I think you're time would be better spent in finding a good reflector,by good I mean 1.2 meter molded,and then use your skills to mount and make work on the C band mount.You'll be much happier in the end.
My 1.2m Primestar is mounted on an old Cband polar and works great from 72w(not much to look for east of that) to about 105w(the roof gets in the way after that).Took some froggin around to get it working but it wasn't that bad.

 

[Anole]

alternatives

Your goal isn't real clear.
But since you on already have FTA experience, let me suggest two alternatives.
.
Less capability but cheap:
- recycle one of the larger DirecTV Slimline dishes, mounting your own LNBF.
.
More of everything:
?- mount 1.2 mtr GeosatPro dish from SatelliteAV onto a STAB H-120 motor.
.
Don't forget, you would need a vbox/gbox to run the existing mount/motor, if it still functions.

 

[. Raine]

Northgeorgia,
Thanks! These pages were helpful.

 

[northgeorgia]

No problem. The vetrun site was the one mentioned by Anole, and was posted here several years ago on this forum. The other one I found on my own and looks to be from a guy in India...too bad we never found out the results of his experiment Best wishes!

 

[. Raine]

Thanks everyone for the replies, I'm pretty sure this project will be a go, so I'm going to put in the extra pole for it. Turbosat, i swear that I'd found the thread of your build a couple of nights ago but I just looked for it again and couldn't find it. Thanks for mentioning the tilt, I hadn't thought much on that, looking at the polar ring again and the angles made me think the dish probably wouldn't be able to tilt down far enough the way I'd envisioned mounting it. Thinking now that I may use a nice looking mount that I have from an old pizza dish welded onto a bracket on the polar mount to give me room for adjustment and go with 1 meter for the dish. You probably saved me a lot of headache mentioning tilt, thanks. Sorry Anole, I probably should've explained a little better my goal, a bigger Ku dish than what I now have, 76 cm. I could definitely afford to buy one or probably find a used one if I looked hard enough, as has been suggested. I figured I already have all this stuff and it'd probably be fun to do and the motor I'm thinking would work better than anything I could buy for a Ku setup. I have the welding equipment and metal, I have a few lnb's just hanging around doing nothing, a couple of receivers, the polar mount, a bunch of pizza dishes I've picked up here and there even though they're pretty much useless, I've got pretty much everything I need to do this, I think. Except a vbox/gbox for the motor, like you mentioned. The motor I have does have a broken housing but still runs, but it looks to be an aluminum housing so I should be able to tig weld it back together. Speaking of motors, vbox/gbox, is there a major difference between the two, or are they both pretty much the same thing?

 

[Anole]

There are a couple of Vboxes. The Gbox is far superior but no longer available.
See reviews for more info
Another coming controller that should be exceptional, is:
http://titaniumsatellite.com/news.html

Might be available by the time you need it.

 

[. Raine]

Thanks Anole,

The link didn't work for me but I went to their site and saw it, the ASC-1 positioner/controller? That does look to be real nice, wish they listed a price for it though. They also have a C-band PLL LNBF in their new section listed to be available in October, which looks interesting. Looks like they must be a newly started company? Some of their site doesn't seem to be finished yet and the only contact for them I saw was Facebook at the bottom unless my computer is messing up and blocking scripts or something, I'll probably try to look again tomorrow on my other computer or boot into Linux and do it. This computer's been messing up on the Vista install for me the last week or so and I haven't bothered much in trying to figure out why because I've already put another one together to replace this junker but have been procrastinating in swapping them out, lol, been spending to much time messing around with satellite stuff! Like I've seen other people on here say, it starts with one dish, and then....

 

[Anole]

Can't really say ny more about Titanim at this time.
When news is available, it'll get posted here.
?Backed by very reliable source, though. That's why I mentioned it.