Is there any kind of kit to use multiple feedhorn/LNB's on a single dish?

[ancient]

Let's say you have a dish that looks like this:

Or this:

The idea being that it is a dish where the LNB is supported by four support arms coming from the outside rim or an inner support ring on the dish. Now if you have that kind of dish, is there any kind of kit you can buy that would let you attach TWO scaler rings and LNB's to receive nearby satellites? I think I remember reading somewhere that for some reason the minimum spacing was 4 degrees, due to the physical size of the scalar rings, and I don't know what the maximum would be, but let's say you wanted to receive (just as an example) a satellite at 99 degrees and another at 103 degrees, or maybe 105 degrees. Assuming one has no access to a metal shop and isn't real handy with fabricating parts, is there any kind of kit or bracket you could buy that would let you do this?

What about 3 LNB's on the same dish, would that be possible?

Any idea how much the signal might be degraded by not having one or two of the LNB's pointed at the direct center of the dish?

Or is none of this possible because the mounting poles would get in the way of any such arrangement?

Obviously I would want something like this for use with a fixed-position dish, not one that moves!

 

[fred555]

There is anothet thread on the subject somewhere where these are mentioned:
http://www.tek2000.com/cgi-bin/web.cgi?command=product&item=C-Band Dual Focus Scalar Ring-ND

I can't remember if they were any good.

 

[Jason S]

Not exactly a kit, but some pretty neat mounts fabricated for multi-LNB and LNBFs in Post # 269, found here:
http://www.satelliteguys.us/xen/threads/pics-of-the-dish-farm-post-yours-too.131140/page-11

 

[iBoston]

http://www.aliexpress.com/item/New-...nna-LNB-Brackets-Free-Shipping/571830473.html

I ordered one.. Ill let you know how it goes.

 

[ancient]

There is anothet thread on the subject somewhere where these are mentioned:
http://www.tek2000.com/cgi-bin/web.cgi?command=product&item=C-Band Dual Focus Scalar Ring-ND

I can't remember if they were any good.

That one is interesting but unfortunately it's not for dishes with four support rods:

NOTE 2: Attaches to 3 LNB support rods. If your dish has 4 support rods, remove one and space the remaining three equidistant around the dish rim and bolt the rods so that the scalar ring axis is aligned with the satellite arc (Clarke Belt).​

I really don't want to remove any of the supports so that one wouldn't work for me. Also it looks like the second LNB doesn't have a full scalar; I wonder if that matters?

 

[ancient]

http://www.aliexpress.com/item/New-...nna-LNB-Brackets-Free-Shipping/571830473.html

I ordered one.. Ill let you know how it goes.

I appreciate that. One thing that confuses me though, it says on the page:

New Design LNB Brackets, Use for C-band / Prime Focus Antenna

Use this LNB Bracket to add a second LNB to any 30``, 33`` , 36`` , or 39`` FTA Dishes​

If it's for C-band, why would they specify those dish sizes? I've never heard of anyone successfully pulling in C-band on a 30" dish! I wonder if they just copied that line from the description for a similar Ku-band product and forgot to change the sizes.

Again, it looks interesting. Personally I would feel better about it if it had more than one support rod, especially since I live in an area where there can be a significant snow buildup on an LNB in the winter. My fear is that the smooth clamp against that smooth rod would work fine until it got some snow weight, or maybe a high wind on it. But maybe it's not as bad as it looks and it really will hold its position. I'll be interested to know what you think after you get yours!

 

[ancient]

Not exactly a kit, but some pretty neat mounts fabricated for multi-LNB and LNBFs in Post # 269, found here:
http://www.satelliteguys.us/xen/threads/pics-of-the-dish-farm-post-yours-too.131140/page-11

I assume you are talking about these:

At least they have the right idea of using plenty of supports:

Words fail me on this one :

These pics (well, at least the top three, and especially that third one) are definitely more along the line of what I was thinking of, it's too bad there isn't a pre-made commercial solution like that!

 

[Jason S]

I assume you are talking about these:
These pics (well, at least the top three, and especially that third one) are definitely more along the line of what I was thinking of, it's too bad there isn't a pre-made commercial solution like that!

Those are the photos. To me, McGuyver's multi-LNB setups in the photos appear to be well thought out, neat and simple yet sturdy using inexpensive parts (flat aluminum stock, aluminum channel, electrical conduit clamps and a few nuts and bolts).

If you don't find a ready made multi-LNB(F) holder, at least there are workable alternatives.

 

[ancient]

Those are the photos. To me, McGuyver's multi-LNB setups in the photos appear to be well thought out, neat and simple yet sturdy using inexpensive parts (flat aluminum stock, aluminum channel, electrical conduit clamps and a few nuts and bolts).

If you don't find a ready made multi-LNB(F) holder, at least there are workable alternatives.

Right, that definitely looks doable. I realize the minimum spacing is 4 degrees and then only if you overlap scalar rings as shown in the last picture, but I wonder if there is any kind of formula as to how far apart the LNB's must be for each degree of spacing. But then I suppose that would depend on the size and depth of the dish. My only issues with that kind of mounting are the question of how well it would hold up under a load of heavy, wet snow without bending anything, and whether the fact that the LNB would not be pointed at the exact center of the dish (because the supports aren't curved at all) would degrade the signal significantly.

I suppose a mathematician could come up with a formula where given the diameter of the dish, the depth of the dish, and the number of degrees separation between the satellite you are trying to receive, it could calculate exactly how far apart (center to center) the LNB's need to be, and what the curve of the extender rods should be (though my guess is that curve would exactly mirror the curve of the dish itself). But whether you'd pick up any appreciable signal gain (more than a point or two of quality) by calculating with that precision is an open question. And anyway, I'm not a mathematician, so for me doing something like this would be all trial-and-error.

 

[gabshere]

ok i'm no expert at it but did get the chance to play with multi lnb's on one dish for a few hours last year . I don't get a lot of time to play with my dishes since i work out of state. this link shows several lnb's in a temp setup using conduit hangers.
although they are flimsy and shouldn't be used for anything more than playing / testing (for length of something more sturdy) mine only got 91,99,105 in testing so your mileage may vary its a project i hope i get more time this year to play with some more

 

[richyrich]

Here is the directions for multi-c band. They did not write directions for using a satellite dish without shadows after the cable companies put fences up to hide their dishes. Here is a picture of the design I have used which is offset for elevation accrued using the middle of a c band sized dish; for c or ku band sized dishes used my hands on the lnbf; from behind the dish to southern exposure; holding the skew and the stable aimed point using a bracket is easier. The problem is if the assembly moves a 1/4 inch; it stops working; so static bracing is required; and very good switch; and all lnbf's must be isolated from the mirror (satellite dish and associated ground; diseq sw is half of the assembly. Plastic or glass are the only materials for the isolation factor removes the dish from "electrically being ground as it is actually id's making an amount of electricity the lnb". The switch used only powers dc one lnbf at a time.
http://richtv.net/picsir.png
How it is done today using a ku dish is the AZ/EL mount that uses its "offset" design to give you one satellite at offset using the middle of the dish; and the marked elevation for when the pipe is a vertical. DBS dishes do the middle of the dish iused for one satellite the middle lnbf receives and skews to the 4 satellites it receives. The other satellites are aimed at using the assembly (dish toroidial feature built-into the dish; accruing aim of each. The picture from my link is when a dish plate is horizontal; the offset is the lnbf aimed to the middle of the dish from each offset; using offset as both AZ and EL from the true mirror and amplification a satellite dish has available to it (both angles) from the center of the dish. Motorized dishes were designed to move to all that is offset today; they only needed one lnb (then $1000) and the shadow was small because of only one lnb. Offset dishes upsidedown and backwards have no shadows to ANY OTHER SATELLITE FROM THE PLACED LNBf's onto the assembly. This is the same as taking a glorystar dish and using it upside down (; from where i live the lnbf is almost vertical because of itheir offset design (; with a re-movable offset their brackets..+24 lnbf's and is about $240+12 brackets for the ku band only assembly. They just do not write their instruction book for its use. Many parts on the dish; like the lnbf bracing are shadows to many lnbfs. The shadow is minor with only 1 lnbf. Keeping the assembly from shadowing each other is why it has to be offset; and if you look at directv's lnbf why 2 degree spacing is really hard to accrue. The lnbf's today are not designed for 2 degree spacing as the "bump into each other" unless they are cut and isolated from each other like directv's ku band lnbf as an assembly; or for FTA uses.

 

[migold]

I am using pipe clamps to attach a second LNBF. On my 8' dish, I get 6 deg. spacing for 99W (Focus) and 105W (offset), at best. On my 10' dish, I get 4 deg. spacing for 97W (focus) and 101W (offset).

 

[richyrich]

offsetting LNBf's from a center focus designed for one lnbf shadow only; means that the more lnbf's you mount, the more each cause shadow to each others direction it receives from. The DBS type is around 8 degree's also because of the shadows at aim for their spacing of the satellites; and ku band is small area of shadowing (nlockage of signals). Just like a c band dish needs the entire dish to reflect an entire satellite; always the middle of the dish is aimed at. Notice DBS dishes do not aim every lnbf/eye/cavity at the middle of the dish (C Band LNBf's must aim at the middle to achieve optimum signal gathering of the energy reflected; SO EVERY LNBf must achieve its "aim" using the middle of the dish. The offset for elevation sets the elevation of the lnbf aimed; the az is set with the middle of the dish at the same time for full satellite signals without any shadow/blockages by the other lnbf's mounted next to it. Then the entire dish can actually receive every satellite the plate can be aimed at; using offset for elevation AND AZ! The assembly looks like this picture

now look inside dtv's 3 satellite offset @ 2 degree's and that really is one feed; 3 satellites; ku band satellites circ. polarity; no shadows; 3 gig = 1000+ channels stacked and right on down the cable to their receiver; prefectivly. In Alaska; a satellite dish almost has to ne mounted upside down and sideways.

In the old days, while the concrete hardens; pipe/post/pole for polar mounting; I would take the assembled c band dish W/O mount; and point the dish straight up; then using my hands holding the feedhorn; i would plug a hdtv in next to the dish; and watch channels by aiming the lnbf at offset and AZ; across the middle of the dish
AND WATCH TV; you can too; to get every satellite at 4 degree's the scalars need to be cut physically to fit; and the dish must be mounted po nting straight up; and to get both c and ku the ku or whatever collector you mount must all aim at the middle of the dish; and curve; or follow the arc of and skew if any; of and with every lnbf; without shadowing each other the Design is already a fact!!