Thread: Im trying to make my own Ku/C Band Feedhorn but I am failing

Inspired by what I saw on some other thread I cant find right now (I think it was made by "Paragon" who combined 4 C band feedhorns on his BUD) I tried to put to use one of the old chaparral C Band feedhorns I have lying around and add some Ku Band to it by using an universal ku lnb. Now my dish is a 10 footer and I have had success using this universal ku lnb (mainly used for offset plates) on my BUD by using a Ku on a C dish bracket like you can see in the following pic:













as it is right there in that pic I can get every channel @ 97, 101, 105, 94, 93, 85 and 83, which is about as good as im gonna get if I go by what the beams show for my area (near Mexico City, I get no beam for 87, 91, 99, 103).

Since I got fed up with the C/KU lnbfs that I bought and never worked (if interested you can check out my sad story here http://www.satelliteguys.us/c-band-s...at-6000-a.html
and here: http://www.satelliteguys.us/free-air...block-buy.html) and buoyed by the fact that I was getting a decent signal with this offset Ku LNB plus knowing that my C band chaparral works very well on the C band side I went ahead and tried to combine both thinking if I kept the ku band lnb close to the center and at pretty much the same length I might at least get something but unfortunately I have not been able to get any strength of signal yet on the Ku side, meanwhile the C band reception I get is pretty much the same as with the other untouched Chaparral Feedhorn I normally use, here is the final product:









before I even made this ghetto corotor I even tried positioning the ku band lnb above the chaparral and even below it, always keeping it in the center but same results no ku band.

I guess my question is am I completely wasting my time with this experiment? what suggestions can you all make so that I can at least get some ku band to complement my great c band experience without shelling out the big bucks for a corotor (which I probably will still end up buying)

I read your post three times to see what you were actually asking.
I was distracted by the in-line pictures....

Are you saying you NEVER got any Ku on that BUD with the little Ku LNB, or just never got Ku when the Ku LNB was beside your C-band LNBF???
Did you move the dish a few degrees to recenter the Ku lnb on the satellite?

Another consideration is that you won't get great Ku signals with that LNBF on a BUD, because the F/D ratio is not optimal.
The LNBF expects about F/D=.7 (maybe .6), but the BUD provides F/D =.3 to .4
....meaning that your Ku LNBF is looking only at the center of the dish, not all of it.

I'd suggest you search our Gold Sponsors for something
like this LNBF

, designed for your exact need.
Alternately, look up the Invacom AF-120 feedhorn, and get a suitable LNB to mount to it.

Originally Posted by Anole

I read your post three times to see what you were actually asking.
I was distracted by the in-line pictures....

Are you saying you NEVER got any Ku on that BUD with the little Ku LNB, or just never got Ku when the Ku LNB was beside your C-band LNBF???
Did you move the dish a few degrees to recenter the Ku lnb on the satellite?

correct, never got ku when it was besides the chaparral and yes I moved the dish but nothing, seems that that particular ku lnb has to be EXACTLY at the center in order to work on my dish

Originally Posted by Anole

Another consideration is that you won't get great Ku signals with that LNBF on a BUD, because the F/D ratio is not optimal.
The LNBF expects about F/D=.7 (maybe .6), but the BUD provides F/D =.3 to .4
....meaning that your Ku LNBF is looking only at the center of the dish, not all of it.

I'd suggest you search our Gold Sponsors for something
like this LNBF

, designed for your exact need.
Alternately, look up the Invacom AF-120 feedhorn, and get a suitable LNB to mount to it.

I kinda knew that going in but still was wondering if it was possible. Thanks for the suggestions, especially that geosat pro lnb for prime focus!

the only question I have about that geosat lnb is how to mount it on my dish, would I need the bracket and hold it by it's "throat" like I do with lnb I posted in the first pic or does the ring come with holes

The GEOSATpro SL1P has a 40mm throat for mounting in a traditional LNBF clamp.

Originally Posted by Anole

....Another consideration is that you won't get great Ku signals with that LNBF on a BUD, because the F/D ratio is not optimal.
The LNBF expects about F/D=.7 (maybe .6), but the BUD provides F/D =.3 to .4
....meaning that your Ku LNBF is looking only at the center of the dish, not all of it.

I'd suggest you search our Gold Sponsors for something
like this LNBF

, designed for your exact need....

I don't understand why that SL1P LNBF would work better on a prime focus dish, it's specs show it to be designed for a .5-.7 F/D?

Is it the little flat scalar, or......?

My expertise is very limited in this area, & I have never experimented with this, but on a C/Ku LNBF the Ku is 8"-10" past (higher) then the C part. Wouldn't you then need to move this farther away from the dish to get signal? Also I'm guessing this is just a fun project for you so keep up the good work. It's very interesting

I'd go with the Invacom ADF-120 prime feed. It can be adjusted to match the f/D of almost any BUD. You can get a small variety of Invacom LNBs to attach to the flange on this feed, but some are hard to find and a bit pricey. Instead, the DN Superdish FSS 105 or 121 LNBs are very good, fit this flange and usually go for a song on eBay.

You might consider putting the Ku feed dead-center and offsetting the C-band side. Given that most BUDs don't focus well at Ku frequencies, this is probably your best bet. If you had a perfect dish, you would do a little better by offsetting both feeds from center by the same amount, but I would not suggest this for a mesh dish. Whatever you do, make sure that when the dish is exactly at true south, the centers of both feeds are on a horizontal line.

Originally Posted by phlatwound

I don't understand why that SL1P LNBF would work better on a prime focus dish, it's specs show it to be designed for a .5-.7 F/D?

Is it the little flat scalar, or......?

well it does work I tried 3 LNB's a while back with the 6 footer for a member

http://www.satelliteguys.us/1903812-post13.html
I have a 6 footer set up with it just in case I find a low quality feed that I really want to watch