Feedhorn Modification Possible?

[dougbrown]

I recently acquired a dish that I believe is identical to the one in this photo (credit to phlatwound for the picture) http://www.satelliteguys.us/attachment.php?attachmentid=40924&d=1250182016
I'm playing with the feed-horn and it looks to me like it might be possible to modify it to accept a second lnb in a horizontal orientation thus creating a makeshift ortho feed-horn. Has any one else tried this or have any thoughts on such an endeavor?

 

[phlatwound]

Can you take a pic of that unit without that plastic piece that covers up the "forward" end of the Rx LNB?

That might give the mad scientists here an idea of what you are talking about.....and I would like to see what's under there, never took mine apart.

 

[Anole]

I don't see why not.
Might be a problem finding the right plumbing to mate up, but now that you mention it, ya seem to be on the right road.
Right now, there is probably a transmit filter in the transmit chain.
That'd have to go to get receive signals through.
Never had one of 'em apart, so I'm anxious to see what 'cha got, too! - :up

From what I've seen of the DirecWay dishes, they don't have the nice hardware you might be lookin' at.

 

[dougbrown]

Ok here are some pics

I tried to take some quick photos of the feed off of my latest dish, and got a bit carried away. I ended up shooting all of them. The quality of the feed shots isn't that good but may help clarify things a bit, at least you can see the two feeds are in different orientations H & V.

 

[dougbrown]

No thoughts? or am I just being unclear?

 

[Anole]

I was sure we had some experts who could help ya, Doug.
Have seen mention of an adapter (actually called a transformer) to adapt the LNB between round and rectangular.

Here is what I was picturing while thinking about your problem.

Don't give up, I'm sure there is a simple solution.
Plus, I like the big feedhorn.

edit: wait!
I just looked again at your first picture!
(All those BUD pix were distracting!)
Can't you just bolt on two regular Ku LNBs to what ya got there?

Naw, I looked once more, and don't know what I'm seeing.

 

[Shawn95GT]

It should be doable. I did somethign similar with a VSAT dish I got off craigslist:

Mine originally had a notch filter in it which I removed and bolted a LNB in it's place:

 

[dougbrown]

OK, the first pick shows both the feed outputs on the feed assembly. the vertical on the left and the horizontal on the right. The vertical was where the reception lnb was mounted, and the visible portion of it is clear of obstructions. The horizontal feed is where the transmitter was mounted, and it has a system of baffels on it to the point where I can not see light through it, but air passes freely. The second pic is an attempt to show part of the baffles. the third pic is where the conical feed horn mounted. it was originally covered with an opaque plastic, but the sun cooked it. there was also a membrane just inside where the feed horn mounted onto the assembly, it was all dried out and damaged so I removed it. The first two bud pics are my second bud, still in the assembly stages. I don't have the actuator on it yet. The stand for it is an idea I developed with a friend of my who has alot of old iron and welding equipment. Eventually I will be able to drag it any where in the yard I want and level it within a few minutes. Then I have a couple of shots of my (Prodelin?) offset dish, which I'm hoping to eventually have multiple LNB's on it, but it's still in setup at this time. The NPRM came with it as well all for the best of prices $0. The last shot is from behind my Radio Shack perforated 9ft H2H.

 

[pendragon]

If there are baffles, you would likely have to find a way to eliminate them. They are there to prevent Tx-side energy from reaching the Rx side and will filter unnecessarily for dual Rx use. The photos are too blurred to see any details in the throats, but the LNB-side ports do appear to be in the correct configuration for orthomode use. The devil is in the details, so without them I can't say for sure.