Three LNBs C-band/Ku/DBS... No problem

[bigOleB]

Now this is a creative way of making it happen with three LNB's and a big ole scalar ring...

 

[Shawn95GT]

I saw that yesterday and was thinking that it'd be easily re-creatable.

It looks almost like hot-glue was used to secure the DSS LNB to the C-band one.

A setup like this is why I was trying to understand how a scaler ring works. I understand what it does.... I want to know how it does. If the rings are insignificant other than for stiffening purposes it's all good. If they actually do something than a couple feedhorns poking through will probably wreak havoc.

 

[bigOleB]

That was my thoughts exactly... BUT

The scalar ring is designed to block interference from other sources. If this holds true, theorectically the other LNBs would not help or hurt the rings ability to block noise or so one would believe.

 

[Shawn95GT]

Looking at the positioning of the Ku LNB feedhorn to the waveguide opening for the C-band... I know my Ku LNB wouldn't put up with that. It's too close and forward of the opening.

It may not be a factor for the c-band wavelength though.

Shawn

 

[spyder]

Now this is a creative way of making it happen with three LNB's and a big ole scalar ring...

I've been doing this with 4 lnbs on a 10 ft system for some time now.

http://community.webshots.com/album/100919814SUmqRr

 

[zodiak]

:shocked Wow!!!! :shocked
What a setup, man! You are my hero!

Do you mind me asking what are you using the elvevation servo for? I'd also be interested if you post some comparison between you feedhord-mounted Ku LNB vs. the Invacom.

Great job!

 

[spyder]

:shocked Wow!!!! :shocked
What a setup, man! You are my hero!

Do you mind me asking what are you using the elvevation servo for? I'd also be interested if you post some comparison between you feedhord-mounted Ku LNB vs. the Invacom.

Great job!

elevation servo? I'm not sure which part you are referring to there. ?

The quality readings between the Norsat ku lnb and the Invacom lnbf are actually about the same, even though the Invacom is at about a 2 degree offset from the central feed throat. I mainly use the Invacom for the atlantic region where the 'low-band' ku signals reside.

 

[zodiak]

elevation servo? I'm not sure which part you are referring to there. ?

Well, this question is not directly related to this thread. I'm talking about this photo.

The quality readings between the Norsat ku lnb and the Invacom lnbf are actually about the same, even though the Invacom is at about a 2 degree offset from the central feed throat.

I assume you use adjusted angles when you position your dish, right?

 

[spyder]

Well, this question is not directly related to this thread. I'm talking about this photo.


I assume you use adjusted angles when you position your dish, right?

Oh , that's the gear/chain drive for the horizon to horizon mount. That simply moves east/west along the arc. All the elevations/declinations are preset in the dish mounts and hrdware.


Yes, when tuning in a signal with the Invacom I need to track about 2 degree west of the actual satellite location to get the proper bounce angle. Same goes for the dss lnb exept to the eastern side.

 

[zodiak]

OK, thanks spider, I guess that wheel is attached to a worm screw or something like it...

Another question, did C-band performance changed at all when you cut the scaller to attach those Ku LNBs?

 

[spyder]

Actually I noticed no difference at all in any signal reception after the scaler machine work.

It started as an experiment just to see how well I could get signals locked in on the extra lnbs' , and it turned into a serious project after I seen how well it really worked. I know this is a slight 'missapplication' of the hardware, but hey, it' working well so far.

 

[jerryt]

Hey Spyder

How does your KU LNB get the proper skew for each satellite with your polar mount.

The LNB doesn't tilt as the dish moves does it?

 

[spyder]

Hey Spyder

How does your KU LNB get the proper skew for each satellite with your polar mount.

The LNB doesn't tilt as the dish moves does it?

Yes, it rotates long the axis just as the dish does. The main Norsat lnb has mechanical skew adjustment but once set really doesn't need any adjustment as the dish moves from east/west. The Invcom also is set at the horizontal plane at true south, so as the dish rotates it also rotates/skews automaticly along with it. Really in the same way a ku lnb skews itself on a smaller offset dish as it rotates.

 

[jerryt]

Hey Spyder

I can see how the Polar Mount follows the satellite arc, but I don't understand how it would change the skew of the dish.

I can see how with a HH motor the offset arm on the motor causes the skew to change fron East to West.

Could you help me understand this? Does the KU lnb actually have a physically different skew when most West and Most East?

Thanks

 

[spyder]

Hey Spyder

I can see how the Polar Mount follows the satellite arc, but I don't understand how it would change the skew of the dish.

I can see how with a HH motor the offset arm on the motor causes the skew to change fron East to West.

Could you help me understand this? Does the KU lnb actually have a physically different skew when most West and Most East?

Thanks

It has the same effect on a polar mount dish as it does on an offset arm refelector. The physical laws of rotation are still the same. Only difference is, that a small offset reflector is actually just a small portion of a large prime focus dish. The offset dish reflects the signal at an offset angle into the lnb instead of centering the signal focus to the centered feedhorn.