found my error

[truckracer]

This goes back to last summer with my 10' sami dish.
This dish has never performed as well as i thought it should. changing various feedhorns and lnbs among other things it has never significantly out performed my 7.5' except on s2 signals.

I started messing around tonight and low and behold i found that somehow my feed was 1/2' off center on the struts. I re measured and got the scalar all centered up from the edges of the dish. You wouldn't believe what 1/2" can do.
My signals have shot to the moon.

also the dish had to have the elevation adjusted a bit to properly illuminate the dish with the feed properly centered. I thought i had centered it before but somehow it got out of shape.

anyway it booms now and my 7.5' won't touch it.. time to put the norsat 8115 back on.

 

[Anole]

Congratulations! - :up

That's the kind of story we want to hear. -


. . . and it should be part of any BUD alignment FAQ, too!

 

[Cadsulfide]

good detective work

 

[brentb636]

Great job, it's almost an inspiration.

 

[truckracer]

I am even OCD when it comes to that kind of stuff and i don't know how that slipped by me.
I just had this feeling to get out the tape measure and start measuring. I have thought about making some type of device like a an alignment tool that will be light weight enough that you can sit on the face of the dish from the edges to show you the center where the feedhorn should be.

You should see how far off the slotted holes on the struts that center really is.
the scalar is all the way to the end of a couple of the slots and in the middle of the other two.

I used an inclinometer to properly align the feedhorn to the scalar- that corotor fits very sloppy in the scalar ring.

 

[Sadoun]

Congratulations. Centering feed to a prime focus dish is mighty important.

 

[Corrado]

When we reassembled the 6' Fortec dish recently, I learned how critical it was. I figured it was off when I noticed that C and Ku required re-aiming on the same sat. It looked OK visually, but was no where close.

I had a piece of pipe that fit in the scalar perfectly and carefully slid it through down to the dish. It touched about half way off the center plate. I used the pipe as a guide and tweaked it until perfectly aligned. I also have a automotive style hose clamp on the backside of the LNBF and a few layers of tape to help keep it straight in the scalar. I wish those generic rings had 3 set screws instead of one.

 

[LocutusOfBorg]

This goes back to last summer with my 10' sami dish.
This dish has never performed as well as i thought it should. changing various feedhorns and lnbs among other things it has never significantly out performed my 7.5' except on s2 signals.

I started messing around tonight and low and behold i found that somehow my feed was 1/2' off center on the struts. I re measured and got the scalar all centered up from the edges of the dish. You wouldn't believe what 1/2" can do.
My signals have shot to the moon.

also the dish had to have the elevation adjusted a bit to properly illuminate the dish with the feed properly centered. I thought i had centered it before but somehow it got out of shape.

anyway it booms now and my 7.5' won't touch it.. time to put the norsat 8115 back on.

1/2 an inch or 1/2 a foot? If 1/2 an inch, I didn't think C band would be that fussy.

 

[Anole]

When we reassembled the 6' Fortec dish recently....
.... It touched about half way off the center plate.

For those of us who don't have that dish, how far was it?
Two inches? Three inches?

1/2 an inch or 1/2 a foot?
If 1/2 an inch, I didn't think C band would be that fussy.

I assumed he meant half-inch, and it affected Ku band alignment, not C-band reception.
But that's a guess ,and I'd like the actual answer, too!

 

[truckracer]

It hurt c and ku pretty equally. My dvb s2 signals were real flakey in the rain on c band.
Keep in mind rain does not really hurt c band. I knew something was wrong.