Anyone enlarged their BUD?

[Cnut]

Just wondering if anyone has enlarged their BUD to a bigger size? If so, how did you do it? Use a frame from a second BUD and cut the ribbing to the size you needed to increase it, and bolting the ribbing on to an existing frame.

Just wondering, found a field with 4 10-foot BUD frames. Some frames have missing mesh panels. Only one BUD still has polar mount on it.None have the guide arms that hold the scaler rings. (I have spare guide arms in my shed, no problem there) The guy who owns the land said I could have all four frames for $50.

I have a 10.5 footer, but would love to have a 12 or 13.5 footer. Just wondering if anyone has tried this, or will I be embarking on a blind journey if I try to use these frames to make bigger BUD.

 

[beavs2112]

what a coincidence that you mention this topic. I went hunting for what I was told was a 12 foot mesh. Well the tape measure proved it was only a 10. So I politely left without the dish cause I already have three 10 footers. On my way home I realized I will probably never find a 12 footer here in Canada. So then I thought ..... why not make one. I have two identical model ten foot perf type dishes so today I disassembled one and started work on bolting the ribs and panels together on the other one. I will have to find some more mesh somewhere to fill in the gaps but no problem. Here are some pics of the dish I am enlarging. the last pic is a rough sketch of what I am doing. When done I think it will be 13 feet. The key is to use ribs from the same model dish so the parabola curve is the same. ie don't mix ribs from a sami and a wineguard cause the shapes are different. also your feed arms will have to be longer to account for the increased dish size.

 

[Cnut]

Wow, what a great start you have to your project. I will go back and check if any two of those four 10-footers are the same, so my parabolic curve will be the same. Hope they are.

keep me updated. I would like to see how your dish turns out and if you see an improvement in signal strength. Thanks for the ideas.

 

[Jason S]

I'm definitely interested in seeing what both your projects yield...

The key is to use ribs from the same model dish so the parabola curve is the same. ie don't mix ribs from a sami and a wineguard cause the shapes are different.

Another coincidence, as I'm currently refurbishing a 10' Winegard I actually looked over to my 10' SAMI and had a fleeting thought about that.

 

[Magic Static]

You will need to recompute the focal depth and F/D ratio then construct new LNB supports to take advantage of the larger size.

 

[KE4EST]

You will need to recompute the focal depth and F/D ratio then construct new LNB supports to take advantage of the larger size.

Was going to post the same thing. I turned a 6 footer into a 9 footer doing this one time. I think there are pics around here somewhere.
I had to extend the arms to take advantage of the larger diameter.

 

[Cnut]

Was going to post the same thing. I turned a 6 footer into a 9 footer doing this one time. I think there are pics around here somewhere.
I had to extend the arms to take advantage of the larger diameter.

KE4EST can you find those photos and post a link? It would help me alot!
Cnut

 

[FaT Air]

IF you keep the proper shape (parabola) the focal length will NOT change. The F/D ratio WILL change.
Just adding the outer foot of a dish to the lip of the smaller dish will NOT conform to the parabola (it will only block outside interference) unless there's some slight
'massaging' of dimensions from the baseline.
A 'tool' that may be useful Parabola Calculator 2.0

 

[KE4EST]

IF you keep the proper shape (parabola) the focal length will NOT change. The F/D ratio WILL change.
Just adding the outer foot of a dish to the lip of the smaller dish will NOT conform to the parabola (it will only block outside interference) unless there's some slight
'massaging' of dimensions from the baseline.
A 'tool' that may be useful Parabola Calculator 2.0

This is what I found out with mine. It appeared that it didn't really increase the gain much. However it did hold signals better that were borderline.
I will have to try and look, there was a thread about it a few years ago.
FaT Air may have been the one that told me the reason, I was holding signals better at the threshold, was most likely due to blocking territorial interference.

 

[KE4EST]

KE4EST can you find those photos and post a link? It would help me alot!
Cnut

Oh I doubt it, I didn't get real fancy like you are. I took sheet metal and just extended the petals, it wasn't very pretty.

 

[Cnut]

Bummer about the no increase in gain. I may not try this and see what other ways there are for me to get a bigger dish.
thanks guys

 

[FaT Air]

http://www.satelliteguys.us/xen/threads/adding-panels-extra-to-a-6.260928/#post-2587140 ??

 

[fred555]

Just adding the outer foot of a dish to the lip of the smaller dish will NOT conform to the parabola

Correct

The formula of a parabola is not linear, meaning the shape continuously curves at a differing rate, taking
a section of the existing parabola and moving it outward, does not form the exact correct shape.
That new last foot is not the exact correct curve.

Theoretically: One could actually take measurements on an x/y axis of the dish, derive the correct parabolic equation, then using the derived equation, construct the correct parabola for the last new foot of the dish.
Also, even when extended to infinity, the focal point of a given parabola is constant.

 

[. Raine]

I've thought on this a bit before and was thinking that extending the dish in the center a bit might work better as far as keeping the parabola shape as long as it wasn't extended too far, but it also would double or triple the work involved because the work being done in the center of the dish would mean that pieces would have to be made to fill in the gaps between the outer parts of the dish created by doing this.

Never worked through the math for it to see if it's feasible because I'd decided to just make a C dish from scrap but kinda set that project aside when I picked up a 12'.

 

[beavs2112]

FaT Air Thanks for that link. It will definitely come in handy when building my new enlarged dish. Here's a pic of the ribs that the dish uses. The bottom curve is where the mesh goes over facing the satellite. So my original plan was to just bolt the extension rib to the existing rib like this So this way the width is 416cm and the depth is 116cm. Feeding that into the parabola calculator gives a F/D ratio of 0.22 which is wrong cause my dish has an original F/D ratio of 0.35. But all is not lost. I think I can fix it by pivoting the extension rib at the edge of the dish to get the more of the right curve (see attached pic "new curve"). Also I can cut the ribs to make the curve steeper if necessary.

What do the experts think? Is this doable? Your honest opinion would be appreciated.
Here are two pics of the mesh panels

Kevin

 

[Titanium]

Unless you create an extension to continue the parabola, the pattern will have significant side lobes and pick-up unwanted signals from adjacent satellites (decreasing the Signal to Noise Ratio). As others have said, the panel extensions will probably only help attenuate ground/terrestrial noise and not increase the gain on the main lobe for the target satellite. Always fun to experiment!

 

[fred555]

One must figure out y=ax^2 +bx+c for current dish parabola shape then apply to the the extensions.

 

[FaT Air]

Here's W. E. Johns's notes http://www.gizmology.net/parabola.htm

 

[bpalone]

OK, I've been playing with the mathematics of extending my 8 foot dish to a 10 footer. Think I may have a way figured to be able to carry the proper curve out. I like to have a decent plan laid out before starting off on an adventure and as such have discovered that if I expand to 10 feet, my F/D goes from .40 down to .29, but the focal length remains the same, as it should.

That would in essence place the throat of the LNBF about 1.2 inches +/- (an estimate) lower than it is now. Can someone tell me just how important the FD setting is. Just wondering how detrimental it would be to leave it at .40? Or, should one plan on extending the legs in order to place both the FD and focal point correctly?

Thanks in advance.

 

[FaT Air]

but the focal length remains the same, as it should.

That would in essence place the throat of the LNBF about 1.2 inches +/- (an estimate) lower than it is now

Conflicting statements - If the focal length remains the same, the feed placement does not change. Only the scalar placement changes if you readjust the F/D setting.
Think the illustrations here http://adlfeed.com/fp_feed_pat.htm should answer your question about not changing the scalar placement. Leaving the F/D setting at .4. Think the 3rd one down on the left is what you'd end up with -
F/D setting higher than the dish calculation.
One way to lower the F/D, without extending the legs, would mount to the front of the scalar.