Dual C-band Feedhorns... (1 Viewer)

Register Today to see less ads! It's Free!
Status
Please reply by conversation.

linuxman

SatelliteGuys Pro
Jul 16, 2006
3,903
15
North West of St. Louis, MO
Okay, this is gonna sound funny to you veterans, but how in goodness's name do I bolt the LNB's to the flanges? Which way is right? Do the probes have to match? Obviously the vertical isn't, it will be 90 degrees. does it matter?

Its finally dried up to the point I can walk around the Para without rubber knee boots, so I am gonna have a crack at that dual today, sometime.

Maybe this will help. :)

macom2.jpg
 
Register Today to see less ads! It's Free!

linuxman

SatelliteGuys Pro
Jul 16, 2006
3,903
15
North West of St. Louis, MO
Stogie,

I would say that outside one is the Horizontal and the center one is the Vertical.

You should rotate yours 90 degrees counterclockwise, and install it. It will either work or not. It doesn't make any difference which way the LNBs face. They will only fit in one direction. :)
 

stogie5150

Crazed Cajun Rebel
Jan 7, 2007
3,819
46
Slidell,LA
WEELLLLL...after all this time, all this money, and discussion...this will NOT work on a Paraclipse! The Para uses a steel ring to attach the feed legs to, and its only open on ONE side, and in order to skew the assembly properly, AND keep the proper F/D, the waveguide of the feedhorn hits the ring BEFORE alignment of the vertical polarity on the N/S axis of the dish! I tried moving the ring so the opening is in different positions on the dish, no go! :mad:

Pics shortly.

Keep in mind that the whole thing STILL has to go in at least 3/4 of an inch from where it is now for it to even be CLOSE to the right F/D. :(
 

Attachments

  • IMG_1588.JPG
    IMG_1588.JPG
    22.3 KB · Views: 88
  • IMG_1589.JPG
    IMG_1589.JPG
    45.7 KB · Views: 94
  • para2.jpg
    para2.jpg
    24 KB · Views: 110
  • para3.jpg
    para3.jpg
    118.1 KB · Views: 111
  • para4.jpg
    para4.jpg
    108.2 KB · Views: 122
Last edited:

voomvoom

SatelliteGuys Master
Lifetime Supporter
May 18, 2004
6,660
29
Lizella, Georgia Republic
Stogie, I have 2 like the one in your picture. And I say it doesn't matter which is V or which is H. Because they are both V and they are both H. They are both fixed and will not switch, One satellite will have one as Vertical and the other as Horizontal, while the satellite next to it (2 degree spacing) will have the Horizontal on the one that was Vertical and Vertical on the one that was Horizontal on the previous satellite. What will matter is how you have the Skew set, and how you merge the V and H together for the receiver.

Sorry it's not fitting on the Paraclipse.... If you decide to part with it (the dual feedhorn), give a loud holler...
But, I'm sure you will figure something out..!!!!
 

Anole

SatelliteGuys Master
Sep 22, 2005
11,819
12
L.A., Calif.
Can the assembly (feedhorn and all the goodies) be pushed forward to the C-ring in any of four 90° orientations?
It doesn't really matter if your "outside" LNB is up, down, left, or right.
That can be handled in the switch.

If there is interference between the feedhorn and C-ring/bracket, how much grinding on the C-bracket would it take to make clearance?
If a lot, then not a great idea. If just a little, then maybe something you could consider?

Guess I'm not visualizing the problem all that well.


edit: Voom, Linuxman, Stogie... have these dual-LNB feedhorns been around 20+ years?
I like 'em, but figured they were a newer solution.
Or, are they more old commercial as opposed to old end-user design?
I guess 20 years ago, two LNBs would have cost hundreds of dollars and not been popular with most non-professionals...?
 

voomvoom

SatelliteGuys Master
Lifetime Supporter
May 18, 2004
6,660
29
Lizella, Georgia Republic
edit: Voom, Linuxman, Stogie... have these dual-LNB feedhorns been around 20+ years?
I like 'em, but figured they were a newer solution.
Or, are they more old commercial as opposed to old end-user design?
I guess 20 years ago, two LNBs would have cost hundreds of dollars and not been popular with most non-professionals...?
I know they've been around for years, but I think it was more Commercial than End-User too.... But I'm just as sure End-User's did have them..??
 

linuxman

SatelliteGuys Pro
Jul 16, 2006
3,903
15
North West of St. Louis, MO
Stogie,

Is it an attached scaler/adjustable?

If so, you can take it off and use your existing scaler if it will slide into it.

If not, try a cutting torch for the offending parts. :)
 

stogie5150

Crazed Cajun Rebel
Jan 7, 2007
3,819
46
Slidell,LA
Can the assembly (feedhorn and all the goodies) be pushed forward to the C-ring in any of four 90° orientations?
It doesn't really matter if your "outside" LNB is up, down, left, or right.
That can be handled in the switch.

If there is interference between the feedhorn and C-ring/bracket, how much grinding on the C-bracket would it take to make clearance?
If a lot, then not a great idea. If just a little, then maybe something you could consider?

Guess I'm not visualizing the problem all that well.


edit: Voom, Linuxman, Stogie... have these dual-LNB feedhorns been around 20+ years?
I like 'em, but figured they were a newer solution.
Or, are they more old commercial as opposed to old end-user design?
I guess 20 years ago, two LNBs would have cost hundreds of dollars and not been popular with most non-professionals...?


Well if it were ANY other dish that the scalar ring just bolted to the feed legs, there would be no problem. But because the Paraclipse is built like it is, this is a non-starter. :(

The FIRST thing I though of, being a former aluminum shipfitter, was how MUCH I could cut off to make it work.....LOL...but after some on the fly measurrments I would have had to do away with one of the feed legs to give me enough adjustment.

Stogie,

Is it an attached scaler/adjustable?

If so, you can take it off and use your existing scaler if it will slide into it.

If not, try a cutting torch for the offending parts. :)


Same problem , Fred, no matter which scalar I used. I tried it. To get the F/D within an inch that ring would have to be notched farther than the support leg.

And I almost took a hammer to it, much less a torch...I have been plannign this for a MONTH! :)

Sometimes you just have to laugh, though. It happens. Like the Army folks say, " No plan survives first contact with the enemy." LOL

.... If you decide to part with it (the dual feedhorn), give a loud holler...

You have a PM, my friend. :)
 

gabshere

SatelliteGuys Pro
Aug 20, 2006
3,720
21
Rison , Arkansas
was this where all the measurments said the scaler should be of have you tested it with another lnbf


ok you might not like it :(

spacers and longer bolts extent the support arm bracket out some more ( might have to bend either the arm ends or the bracket)
this will also involve getting longer adjustment ( looks nylon or plastic scaler bolts)
this will involve getting the whole lnbf feedhorn between the dish & the support arm holder.


or
and this is going to sound weird
reverse the whole mount ( turn it upside down ) should place the mount closer to the scaler now you would have to figure out how to reverse the tabs that connect to the mounting arms

this should work
or place the mount below the arms with spacers maybe 1 inch scaler would have to be adjusted upwards toward the mount.

or you could make a larger support arm bracket one that the feedhorn fits through but still controls the scaler adjustments
 
Register Today to see less ads! It's Free!

stogie5150

Crazed Cajun Rebel
Jan 7, 2007
3,819
46
Slidell,LA
Thanks for the ideas George, but I have already abandoned the idea unworkable on my dish. Too much effort for an unknown result. :cool:

Brother Voomvoom has agreed to buy the whole shebang offa me, and he is gonna try it.

My future course of action is to wait on the gbox with the skew control, and go back to a regular old-style feedhorn with servo. I have a Norsat LNB I can use on a single feed. So right now that is the plan. :)
 

Lone Cloud

SatelliteGuys Pro
May 23, 2008
701
18
My local C-band guy says that dual feedhorns are inferior to singles with a polarotor.

he says that they work fine for a fixed dish, but not for motorized dishes. He says the fine, multi position control of the polarotor is much superior for skew, and that, especially out on the arc, the dual band feedhorns have to be tweaked and tweaked constantly.

This sounds like it makes sense. Does it?
 

truckracer

SatelliteGuys Pro
Sep 17, 2004
4,338
351
Charleston wv
My dual band dual polarity ortho feedhorn works fine all the way across the arc.
From 43w to 139W.

It tracks just like an H to H motor does on a small ku fta dish.
great strong signals all the way across. Both C and Ku are strong everywhere.

On any sat - no tweaking of the skew will bring in a better signal.
I thought the same thing as the previous post until I got mine tuned.

I would say that my ortho does as well or better than my corotor II. better meaning I probably just have it tuned more accurately.

It gives you the high performance signal of a proven feedhorn design with seperate lnbs with the function of an lnbf when using a multiswitch.
 

ACRadio

SatelliteGuys Pro
Apr 25, 2006
794
0
Near Asheville NC
I can more than make up for the lack of fine skew adjustment by doing away with the waveguide loss of a polorotor...not to mention that servo's are a pain in the buttocks. There is only one satellite where skew is an issue and that's AMC 1 KU...and I have a fixed dish for that. No more servo's for me...thank you...:)
 

Lone Cloud

SatelliteGuys Pro
May 23, 2008
701
18
43w to 139 w is pretty good. I can't get that far east.

Can you guys tell me what lnbs you're using?

Can you tell me how you moved them to get them peaked?



Although I can't argue with your results, I don't think it's the same skew action as an hh motor on an offset dish.
 

ACRadio

SatelliteGuys Pro
Apr 25, 2006
794
0
Near Asheville NC
43w to 139 w is pretty good. I can't get that far east.

Can you guys tell me what lnbs you're using?

Can you tell me how you moved them to get them peaked?



Although I can't argue with your results, I don't think it's the same skew action as an hh motor on an offset dish.
It's exactly the same skew action...it's no different at all. I just aligned the skew to 0 at the due south point, and the feedhorn tilts as the dish moves. It's the same with an offset dish...I have both. The vast majority of offset dishes mounted on a motor have LNBF's with no skew adjustment at all...physics is physics.

I use a pair of Norsat 8115's for C band and a pair of Japan Radio PLL's for KU.
 

truckracer

SatelliteGuys Pro
Sep 17, 2004
4,338
351
Charleston wv
skew is skew

I used to think a polar mount did not track the same (early in my learning days of satellite) but it does.

I forgot about amc-1 ku being twisted around a bit. I still get strong reading on amc-1 ku however I am sure they could be Peaked a bit with some skew control since that sat has an unusual skew on ku band.

I did what Linuxman did , get the skew set on "0" at true south and your done.

Peak a true south satellite transponder - In my case ku since it is the tightest beamwidth..

C-band from there on falls into place.

I with Linuxman ......."NO more servo's for me either!!"
 

rv1pop

SatelliteGuys Pro
Some of the very first dishes did not have the pivot points in a "fixed" location. One point could be moved to track the arc. If you did not set that right, then the dish would not track skew.... Then manufacturers realized they could calculate the attach points for both ends of the JACK as it was called then - it looked just like one - and fasten them permanantly, and less problems with skew. Now with adjusting the "bird in the box" (from bird in the hand story) the problem is mostly mute.
 
Register Today to see less ads! It's Free!
Status
Please reply by conversation.

Users who are viewing this thread

Users Who Are Viewing This Thread (Total: 0, Members: 0, Guests: 0)

Latest posts

Top