"Redneck" feedhorns

[14karat]

Ok, First off... I hope that doesn't offend...
BUT... I wanna know about the homebrew feedhorns I'm seeing using a C-band only with a Ku grafted onto the side of it.
Just how are these working? Are there 2 degrees separation on them or what?
How do they perform well if they aren't in the "prime" of a prime focus, eh?
I've got two old c-band only feedhorns that I was planning to replace with dual units, but... I'm also all about using a hacksaw, duct tape and bailing wire to build a rocketship (hah!)

 

[truckracer]

Mine works great except its not grafted to the side.

I used a cheap dms international c band only lnbf. Then I used a dms international ku lnbf for an offset dish.

I used a large step bit in my drill and drilled a hole approx. 1" or so in the end of the c-band lnbf.

I cut the scalar ring off the dms ku lnbf except for the inner most ring that forms down to the
throat of the feed.

Then I used a bench grinder and trimmed the burrs and imperfections around the ku lnbf.

I made sure it fits snug into the rear of the C-band lnbf.

Now you have to install the c-band unit first to make sure when you put them together that the H and V probes are line up between the c and ku lnbfs. If not one of your lnbf's will have reversed polarity.

After you have your C-band signals in line, hook up the ku lnbf and use a good known transponder on the same satellite. I aligned the ku band (you can look down the C-band lnbf's throat and see into the ku band lnbf and align the probes. On mine the isolator bars DO NOT line up , but it seems not to be a problem.

IMHO I believe my homemade one works better than my BSC-621!

The difference being that the BSC-621 has another scalar ring in the bottom of the C-band part that is a second scalar for the KU band part. That means on a 621 KU signal is being subjected to two scalar rings. I think that is why these 621's are so hard to tune and give a compromised performance.

After you get your homebrew lnbf aligned I used JB weld from the hardware store to adhere it together.

I have one that has been in service for over 3 years on a 7.5' sami mesh.

If you scan a circular polarity satellite or satellite position (Say you blind scan G-11 KU band)
with the homemade one you will get the normal linear tp's but it will also scan in some circular tp's from the nimiq bird. That's the only "downfall" I can see with mine.

 

[truckracer]

Hey some of the greatest engineers have been rednecks LOL

 

[qwert1515]

Truckracer that sounds like an interesting modification, do you have any pictures?

 

[truckracer]

pics

I don't have digital camera (I know I am probably the only person who does not own one). I was trying to get pics from my cellphone camera to my laptop using the usb cable but the Motorola razr v3i won't communicate with my pc.

I guess I could send the pics in a message to someone else's cellphone and they could post them.

 

[tdti1]

I don't have digital camera (I know I am probably the only person who does not own one). .

Your not alone, I don't have a digi cam

 

[Mr Tony]

Ok, First off... I hope that doesn't offend...

You aint gonna offend any of us. Heck, take a look around the FTA area and check out some projects we've done


But to the original question, I had 2 C-band LNB's on a 6 footer
http://www.satelliteguys.us/843368-post1.html

 

[truckracer]

Ice,
I could see how the two lnbf's on a 6 footer would work great because of the large sidelobe reception of a 6' dish at c-band frequencies. You could probably park that thing in the middle somewhere and get several degrees both directions as long as the FEC was not too crazy.

 

[Mr Tony]

I luck out and from AMC3 to AMC4 the elevation is within a degree (my TS is 93W) so aiming it was easy

 

[truckracer]

Ice,
Can you lock 3824H 1808 on amc-3 C-band with a 6 footer?

 

[Mr Tony]

let me try tomorrow