6 foot fibreglass

[Papacito62]

I just recently picked up a 6 foot fibreglass dish that was used for ku band and want to convert it to c band. One small issue I'm having is it didn't come with arms to hold the LNBF and I can't find how to calculate for a off center dish.

the next thing I am wondering is why C band uses a scaler ring and KU band / DSS does not. This dish has a non moving mount so my LNB's will need to be fixed and the scaler ring would get in the way if I wanted to install more than one to get multiple satellites and the satillites are next to each other.


Looking forward to working on this project and the help from you all

In advance........thank you

Papa

[Terryl]

The "Scalar ring" is used to cut down on the side image from other satellites, without this your LNBF will/could pick up satellites of to the side of the main satellite, this can cause problems with the transponders on the main satellite if the side satellites have the same or close to the same frequencies on the transponders.

The Ku band satellite dishes do not have the "Receive Bandwidth" that a "C" band dish does, they have a narrower beamwidth, so the side satellites are not that big a problem, also the spacing on the transponders used for Ku band is a bit different.

And the dish your trying to use may not have the necessary beamwidth to receive more then 2 satellites, if it was designed for only one prime focus satellite the LNB's mounted off to the side will not have that good a signal, and may have fade out problems.

This is why almost all "Multi satellite" dishes are of the elliptical design, they have a wider then normal receive beamwidth and can pick up 4 or more satellites without problems.

The best dish for up to 5 satellites is the one from Wave Frontier, it is called a T55 or a T90, but it is expensive and also requires special LNB's.


And your offset dish can use the scalar ring if you get one that is mounted on the LNBF it's self, you can also get a "C" band LNBF mount for that type of dish, look at the link below.

http://www.satpro.tv/conical-scalar-ring-c-band-lnb-bracket.aspx

You can also get a mount for that dish that will allow the use of a linear motor to move it around.

[Papacito62]

Great info.....thank you

Any idea how to calculate for the brackets that hold the C band LNBF

[Costactc]

I had a 6' prime focus dish whose arms had given out, I had arms made for me. I don't recall the exact mesurement but I think they were 36" in length. You will scan in many sats on the American arc but those tougher sats will not come in with a 6' dish.

[jvvh5897]

Actually all Ku band LNBF have built in scalar--they are stepped conical and hidden under the rain cover. Although one Ku band LNBF that was built into a combined C and Ku LNB has a flat scalar. I haven't seen that conical scalars give all that great an advantage over flat scalars, but it does seem easier to visualize the pattern you get with cone shape rather than the complex way those flat rings interact with the signals they get.

There is a simple way to calculate the length of arms you need. The equation for a parabola is just y^2 = 4* f * x where y is the distance from the center of dish to the edge (y^2 indicates y is squared), x is the depth of the dish from edge to center and f is the focal length. You find f and then figure the distance up from the center to where you are mounting the arms and subtract that from f, and build the triangle for distance to LNB and the distance out toward the edge where the LNB arms go--figure the hypotenuse of the triangle (who says geometry and trig was a waste?).

[hondoharry]

Why would you want to use a 6 ft. heavy fiberglass dish for C Band? It's not practical to motorize.

The legs are unique to those dishes and have special ends for the angles and LNB holder. I have one and have ordered the LNB holder. You can order the legs that fit by searching online. Parts are kind of expensive as few places have them. I saw somewhere the exact EL degrees from dead center and the distances. Good luck with your project.

[Papacito62]

Actually I paid 150 bucks to try to get some spanish programming for my wife as non is available in Canada. I am ok with Univision but I see a few others that I checked I only require a 6 foot as per the beam chart. Two satellites are next to each other with lots of programming but not sure if I can mount side by side like DSS does, I seen on you tube some one did it, I prefer the off center dish because of the snow here in Canada as I did have a old 8 foot 25 years ago and snow was a continuse issue, off center you apply a little Pam and it slides off.

Thanks everyone for the info......great start !

Will keep you updated......next up LNBF off eBay

Papa

[fn59]

If you're in southern Ontario you can pick up Hispasat at 30 degrees west. Lots of Spanish channels there.

[Costactc]

If you're in southern Ontario you can pick up Hispasat at 30 degrees west. Lots of Spanish channels there.

Sounds like he's interested in the Univision and Mexican channels where Galaxy 16 and 19 would be excellent for. Unfortunately, a side feed is usually 5-7 degrees apart from where your dish is actually pointing to.

[jvvh5897]

I do multi linear sats on single Ku band dish, so the same should work for C band--the equations are not changed though. You need lots of room for the C band scaler so you might not be able to physically mount the two LNB next to each other if the two sat are really close. I've found that you need about 10 degrees of arc between two bird to fit two LNB next to each other. DTV is doing some interesting stuff with their LNB feedhorns now though--they use an elliptical shaped scaler and fit closer together birds because of it.

[Terryl]

He needs one of these hummers.

http://www.tek2000.com/cgi-bin/web.cgi?command=product&item=C-Band%20Dual%20Focus%20Scalar%20Ring-ND

And you will also have to re-point the dish so it is right in-between the two satellites.

We use to use a wide band elliptical dish for "C" band, (made by Andrews) but it was a monster and a big pain in the back side to setup, it had a curved bar along the focal areas (matched the curve of the dish) so you could mount up to 5 "C" band LNB's on it, it was about 12 foot wide and 20 feet long, took about 5 yards of concrete on the base to keep it stable, it was too big a hassle (and had a big price tag) so we went back to single dishes for "C" band feeds on the head-ends.

[Costactc]

He needs one of these hummers.

http://www.tek2000.com/cgi-bin/web.cgi?command=product&item=C-Band%20Dual%20Focus%20Scalar%20Ring-ND

And you will also have to re-point the dish so it is right in-between the two satellites.

We use to use a wide band elliptical dish for "C" band, (made by Andrews) but it was a monster and a big pain in the back side to setup, it had a curved bar along the focal areas (matched the curve of the dish) so you could mount up to 5 "C" band LNB's on it, it was about 12 foot wide and 20 feet long, took about 5 yards of concrete on the base to keep it stable, it was too big a hassle (and had a big price tag) so we went back to single dishes for "C" band feeds on the head-ends.

Nice site Terryl, I haven't come across this one before. Unfortunately, most of their c band equipment is out of stock. I will keep this site in mind if I need to replace anything.

[Papacito62]

Ok now that's its summer and on vacation I'm working on the dish

Just want to check my math and see if I know what I'm doing.....

The dish is 70.5 " width and 6.75 " deep is my focal point 46.02 "

Thanks

Papa

[Papacito62]

Ok now that's its summer and on vacation I'm working on the dish

Just want to check my math and see if I know what I'm doing.....

The dish is 70.5 " width and 6.75 " deep is my focal point 46.02 "

Thanks

Papa

Ok that didn't work so I cut down the arms 3" I found oce channel HTS so I must be getting close.....

Focal point anyone befor I cut another 3"

Thanks

Papa

[jvvh5897]

Well the 46 inch focal length would be my guess, but I don't know if you have a prime focus dish or an offset dish, it makes a diff.
I cringed when you said you cut down arms--if they were for the dish, why start cutting?