Converting a 90 cm dish to a 1.2m dish

[spongella]

Has anyone tried or heard of increasing the size of an existing smaller( 90cm or 1m) FTA satellite dish to a 1.2m dish? It would just be a matter of cutting a number of "petals" and attaching them around the circumference of the dish to increase the diameter. Aluminum flashing comes in rolls and would be good as it is reflective, and can be cut into pie shapes and fitted around the perimeter. Granted, a lot of work, but would be cheaper than buying a brand new one. Wouldn't increase the weight of the dish too much and would allow using a small H-H motor to turn it.

Not sure how the increased size would affect the focal distance or focal point. Might be worth a try. Just have to keep the petals in the parabolic shape of the rest of the dish.

I have heard that way back when there was a company that made a retrofit for C band dishes to increase their size.

 

[RimaNTSS]

Increasing size of antenna by adding more metal around dish is just useless spending of time. Better way of converting is getting 1,2m dish instead of 90cm one. IMHO

 

[. Raine]

I've thought of doing it before, but haven't tried it yet. I was thinking of welding or brazing some pieces on in the same manner as you're thinking, in 4 or 5 petals that cover all of the old dish but extend beyond the original edges, using the old dish mainly just as a pattern for the shape of the parabola. I'm planning on trying from a 30'' up to 36''. Another thing I want to try is to just make a dish from sheet metal, which probably will actually be easier than making a existing dish bigger, as long as I do it as a prime focus dish. Have all of the stuff here, just finding the time to try it is the hard part!

I think making a dish bigger would move the focal point outward, so the LNB arm/supports would have to be extended too. Not sure, but I think it would.

A few months back, I watched a documentary on Netflix one night where some people were making satellite dishes in Iran, I think it was? where they had a wooden form in the shape of a dish that was spinning on a motor and they pressed a piece of sheet metal against it with a long board, within a few minutes or so they had a dish made. The show was in another language with English subtitles, but it was interesting. I don't remember the name of it but I'll try to remember to look on Netflix and see if I can find it again.

 

[danristheman]

It was called the dish where they ban satellite dishes.

 

[spongella]

Here's what it looks like so far. Kind of looks like a big sunflower. Next will get some wire mesh (screen) and connect the petals. Might be a total waste of time but never know until you try. If it does not work out then at least I can say I tried it.

 

[danristheman]

Sponge check out Casey website they have someone over there and there is a YouTube video of it to.

 

[fred555]

http://www.cemproductions.org/bridgetoiran/the-dish/

I saw it on TV somewhere a few years ago.

 

[polgyver]

I think making a dish bigger would move the focal point outward, so the LNB arm/supports would have to be extended too.

Respectfully, disagree.
Adding petals does not change the existing paraboloid nor its focal point. It just changes the f/D ratio (makes it smaller, say, from 0.6 to 0.4, maybe?). Providing, that the added petals continue the initial paraboloid.
From the last photos, it does not seem to be the case. The added petals should be press stamped, in 2 directions. Slightly rolling the flat sheet does not constitute paraboloid surface. These petals would create another, big, unshapely focal cloud, not a point, and further from the existing one, thus not contributing to the LNBF.
This idea was realized by a dish making company - I forgot the details, but it was prime focus dish.
Cheers, polgyver

 

[. Raine]

Respectfully, disagree.
Adding petals does not change the existing paraboloid nor its focal point. It just changes the f/D ratio (makes it smaller, say, from 0.6 to 0.4, maybe?). Providing, that the added petals continue the initial paraboloid.
From the last photos, it does not seem to be the case. The added petals should be press stamped, in 2 directions. Slightly rolling the flat sheet does not constitute paraboloid surface. These petals would create another, big, unshapely focal cloud, not a point, and further from the existing one, thus not contributing to the LNBF.
This idea was realized by a dish making company - I forgot the details, but it was prime focus dish.
Cheers, polgyver

So if that was the case, the arm/supports would actually have to be shortened a bit, not lengthened? The feed would have to be a little closer to the dish, if it changed the F/D ratio to a smaller value, right?

Another idea I was tossing around about making a dish was to make a mold out of something, probably cement, in the right shape, that could be used to make a fiberglass dish, [keeping in mind that I'm only thinking of making a 90cm Ku dish] one layer of fiberglass then the reflective material and then another layer of fiberglass. The hardest part of this I think would be sanding the first layer absolutely smooth for the reflective material to lay on, and laying the reflective material with no wrinkles.

Danristheman and Fred555, I think that is the show I was thinking about!

 

[danristheman]

Watch this video this is the one I wanted you to watch.

 

[spongella]

Thanks fellas for all the comments, pro and con. A lot of what has been done has been a combination of experience, common sense, and a little science.

The idea to convert a 3 foot dish to a bigger one was borne out of the realization that there's not much choice in the four foot range; companies that sold them previously now do not. One seller on Ebay has them for about $135 along with a shipping cost about the same. It is a GeoSat Pro dish. I guess it is a GeoSatPro but the picture in the ad just shows a plain dish, no logo, so who knows what the buyer is getting.

What is also interesting is that I rarely see a company logo on dishes these days that are for sale. Yes, logos are on the dishes the major companies. I think it is a matter of pride that a company making dishes should have their name on them. If I have to pay for a dish yes I want the name of the company that made (or sold) the dish to be seen. Fortec did it, DMS did it. It adds to the beauty of the product, and should be displayed proudly by the seller. Also gives the buyer a sense that someone has taken the time to put a little effort in identifying themselves a a purveyor of goods and is proud of it. Doesn't take much effort to place a stencil over the dish and swipe over a few quick seconds with some paint.

Now, sermon over,

 

[spongella]

Watch this video this is the one I wanted you to watch.

Thanks danristheman. Interesting that he does not use the conical scalar ring. This individual's attempt is admirable, must have taken quite a while to fabricate the panel extensions. A great example of American ingenuity and resourcefulness.

 

[RimaNTSS]

there's not much choice in the four foot range

Did you look in the second-hand market? It is actually full of offers at bargain price. Some antennas, after washing look like new and, needless to say, work like new. I would suggest Channel master 120. Great dish, in contrary to those, made of tin, just unbreakable.

 

[spongella]

Yes am scouting around for a 1.2m used dish. You have a good point, clean it up and put back into use.

 

[danristheman]

Thats how I found my 1.2 meter dish on top of the old kroger store got a 30" dish two for one deal.

 

[. Raine]

I have eight used dishes setup here and two new ones, right now. It is good to keep an eye out for used dishes and usually they do clean up good, specially the smaller dishes, but it's also fun to play around and tinker with the stuff too.

Today I messed around for an hour or so with mounting a LNB arm to a metal feed can cover here that's about 20'' in diameter and my wife asked me why I didn't just setup one of the small dishes I have stored in the garage...because I just wanted to see if it would work, which it didn't, got blips on my meter but no lock, if I'd used a PLL LNB, then it might've worked.

 

[polgyver]

So if that was the case, the arm/supports would actually have to be shortened a bit, not lengthened? The feed would have to be a little closer to the dish, if it changed the F/D ratio to a smaller value, right?

As the F stays the same, so the arm/ supports also will be the same (unless, we use some means, like re-shaping the original dish, by stamping press - which is not readily feasible).
By adding extra leafs on the circumference of the basic dish, we only increase its diameter D. D sits in the denominator of the fraction F/D, so, the fraction's value gets smaller.
Making concrete form for manufacturing fiberglass dishes was tried by a sat hobbyist, "satmex1" (or, was it Satcom1?), if my memory serves, from Chicago. I forgot, where he posted his photos.
He did commendable work, but did not get good results. He poured concrete on stretchable fabrics fastened to a barrel. The obtained shape was not paraboloid of rotation, but a surface profiled by a - so called - catenary (this is a curve formed by free-hanging chain with small links). Although similar to paraboloid, nevertheless it was the cause of phase incoherence resulting in the lack of usable signal.
Cheers, polgyver

 

[Jason S]

Thanks fellas for all the comments, pro and con. A lot of what has been done has been a combination of experience, common sense, and a little science.

The idea to convert a 3 foot dish to a bigger one was borne out of the realization that there's not much choice in the four foot range; companies that sold them previously now do not. One seller on Ebay has them for about $135 along with a shipping cost about the same. It is a GeoSat Pro dish. I guess it is a GeoSatPro but the picture in the ad just shows a plain dish, no logo, so who knows what the buyer is getting.

What is also interesting is that I rarely see a company logo on dishes these days that are for sale. Yes, logos are on the dishes the major companies. I think it is a matter of pride that a company making dishes should have their name on them. If I have to pay for a dish yes I want the name of the company that made (or sold) the dish to be seen. Fortec did it, DMS did it. It adds to the beauty of the product, and should be displayed proudly by the seller. Also gives the buyer a sense that someone has taken the time to put a little effort in identifying themselves a a purveyor of goods and is proud of it. Doesn't take much effort to place a stencil over the dish and swipe over a few quick seconds with some paint.

Now, sermon over,

Kudos on the experimentation! I'm curious to see the results.

Just my $0.02.

I completely understand about the cost of a 1.2m dish plus the shipping... On my first FTA seup I wanted quality 'name brand' (or at least industry recognized) equipment.

My first dish is a 1.2m Patriot that I payed full shipping price (same cost as the dish in 2014). My objective was to get everything on 125W and research indicated that I'd need a larger dish for the best reception. I found out that it was drop shipped from Wichita, KS (I live about 90 miles from Wichita). So for my second 1.2m dish I arranged to pickup from the warehouse. As a side note, they both have Patriot stenciled across the dish; additionally, I see Andrews dishes with the red lightening bolt and have similar thoughts to yours.

There are some good points to be made about keeping your eyes open while driving around town. Yesterday, while in the next larger town, I spotted a 1.2m on a closed gas station and a 6' on top of a Ford dealer. I commented to my wife about the 'orphaned' dish on top of the gas station. I've also found a 1.2m dish in town that is behind the former cable office, which I will be inquiring about.

On the other hand, there are plenty of good reviews on the GeoSat Pro dishes here (and retailers). Depending upon your ultimate objective, it may be better in the long run to get the proper dish for your goal.

 

[polgyver]

Found the thread, not exactly as described earlier...
https://www.satellites.co.uk/forums/threads/anyone-tried-to-make-big-dish-at-home.95314/page-7
the post # : 130

 

[spongella]

Thanks for the comments. Two years ago bought a new 6 foot (again, no logo on the dish so was buying an unknown brand) prime focus, set it up for stationary use, but signals kept drifting off and had to constantly re-point the dish. It worked to some extent, and yes an 8 or 10 foot would have been better, but I think the dish itself , consisting of 6 petals was of sub-optimal quality and probably was sagging or just misshapen. The anchoring pole was sunk four feet down with concrete and plumb so it probably was the dish in my opinion. Took it down.

Fooling with different size dishes and experimenting is fun, so will keep this hybrid 4 footer going until something better comes along.

Great group of folks on this forum, all willing to lend a hand with info. Thanks again.