Just Sharing This Modified my CM LNB holder for KU and CBAND

[scopus]

wouldn't the ku band balance be disturbed then?

Yes, but you drop the dish down by 5 to 6 degrees again then Ku comes back in focus. Best to use another jack for the elevation ideally..

 

[danny10]

wouldn't the ku band balance be disturbed then?

The elevation must be reversed for the Ku band orientation.

 

[scopus]

is the result as good as if the C-Band LNB was in the centre without any mods?
i have another idea, another 1.8 !!!! my mrs will love that! i could paint it pink.

No, it won't be as good, and for fringe stuff like ESPN that could be a problem. A changer or as you say another dish is the answer..

 

[scopus]

presume these aren't for sale? @Trust

He may have one left at least he had when I last spoke to him a few weeks ago..

 

[Manikm909]

interesting - so would an elevation jack, save having to be spot on with a traditional arc as it replaces the motor elevation bolt, and then dish angle wont matter...as long as you're roughly in line with the ARC in the first place?

any links to Trusts changer?

 

[scopus]

interesting - so would an elevation jack, save having to be spot on with a traditional arc as it replaces the motor elevation bolt, and then dish angle wont matter...as long as you're roughly in line with the ARC in the first place?

any links to Trusts changer?

Correct, but still best getting it tracking the arc properly.

New Lnb changer

Today I finished the new Fibo lnb changer for 6 different lnb positions . The old one only could turn 180º and was controlled by a Omron PLC . The new one is controlled by diseqc 1.2 via a Openbox F-500 , just made only 6 channels at different satellites . I noticed that with diseqc 1.2 , the...

www.satellites.co.uk

Long thread...

 

[Terryl]

Solve everything, get a dual band LNB

 

[nelson_b]

No, it won't be as good, and for fringe stuff like ESPN that could be a problem. A changer or as you say another dish is the answer..

To my surprise .... after a bit of tweaking on my 1.8 c.m. offset it "was " as good as in the center position
something i never could achieve as a - side offset - on the same dish.

is the result as good as if the C-Band LNB was in the centre without any mods?
i have another idea, another 1.8 !!!! my mrs will love that! i could paint it pink.

see above @Manikm909

 

[RimaNTSS]

After reading this thread, I remembered I have a brand-new positioner from the early 90s. It is designed for Az/El offset antenna, but to be able to receive signals from several satellites. So only one LNB which can be moved. I think, after minor modification, this positioner can be equipped with several LNBs (for example Ku and C)and can work as LNB-changer. One day, I will test it on Channel Master 1.8m.

 

[Terryl]

After reading this thread, I remembered I have a brand-new positioner from the early 90s. It is designed for Az/El offset antenna, but to be able to receive signals from several satellites. So only one LNB which can be moved. I think, after minor modification, this positioner can be equipped with several LNBs (for example Ku and C)and can work as LNB-changer. One day, I will test it on Channel Master 1.8m.

That would work great on an offset dish,(LNB and arm mounted to the bottom of the dish) but on a prime focus dish it would be too much hardware out in front, it would probably degrade the signals so bad it wouldn't be worth it.

I wounder if they still make that puppy??

 

[RimaNTSS]

I wounder if they still make that puppy??

I do not think so.
In fact, there was 9V battery in the set which was made in West Germany.... means the set was made before 1989.
Sure, it is better to be installed on an offset dish.
Actually, it is a very primitive actuator. I think that today is possible to buy small actuators and use them as LNB-changer.

 

[moonbase]

interesting - so would an elevation jack, save having to be spot on with a traditional arc as it replaces the motor elevation bolt, and then dish angle wont matter...as long as you're roughly in line with the ARC in the first place?

any links to Trusts changer?

If you put an elevation jack on your 1.8m setup and used a dual axis positioner such as the RC2000 or one of the "dreamsat" units then you can forget about arc ultra accuracy.
Simply program the azimuth and elevation settings per satellite into the controller and then you auto return to that set of coordinates.

In theory you could have a Ku set of coordinates and a C set of coordinates for the satellites with different elevations, all programmed into the controller and always return to that alignment point.
You could use your current Ku arc as the basis for the controller Ku positions then add another set of positions with optimised elevation for C band if keeping the C band LNBF mounted above the Ku band LNB.

The ideal solution is to simply wad up, go out and get a 2.4m Channel Master dish for C-Band, job done.

 

[Manikm909]

Solve everything, get a dual band LNB

i hear they aint very good....

 

[Terryl]

i hear they aint very good....

Mine works great, it's on a 2 meter dish though, I get "C" band on it just fine, and Ku is great, but I mainly use it for the NASA UHD channel on 127W, one heck of a picture.

I also have one on my 3 meter dish, just takes a 22 kHz signal to switch between the bands, cover the Clark belt on all satellites I can see from my location.

 

[Channel Hopper]

Agreed, electronics at the top, should any water find it's way into the waveguide it would settle in the bottom corner of the waveguide tube well away from the probe entry points and eventually evaporate with the help of the slight heat generated by the lnb. Ideally no water or moisture is welcome within that area

The issue is eliminated if the dish reflector is inverted.

 

[zorrin]

Why don't you place the lnbs side by side on the horizontal plane?
for a C/Ku satellite you would have two orbital positions on your positioner.
Your antenna follows the polar arc, it will automatically be placed in the correct position on the arc.
All you have to do is refine the vertical position of the side LNB, it will naturally be lower than the central one.
Personally I would put the LNB C in the middle and the Ku on one side.

 

[zorrin]

like that

 

[stephan94]

in 2014 I made this montage with a C band LNB from Russia

 

[Manikm909]

Why don't you place the lnbs side by side on the horizontal plane?
for a C/Ku satellite you would have two orbital positions on your positioner.
Your antenna follows the polar arc, it will automatically be placed in the correct position on the arc.
All you have to do is refine the vertical position of the side LNB, it will naturally be lower than the central one.
Personally I would put the LNB C in the middle and the Ku on one side.

when i tried that, i couldnt get a signal - not sure why.

 

[nelson_b]

i hear they aint very good....

Mine works great, it's on a 2 meter dish though, I get "C" band on it just fine, and Ku is great, but I mainly use it for the NASA UHD channel on 127W, one heck of a picture.

I also have one on my 3 meter dish, just takes a 22 kHz signal to switch between the bands, cover the Clark belt on all satellites I can see from my location.

O.k for C band ... but not so good for k/u here in the u.k.

I bought a C - K/U combination l.n.b many years ago to fit on my 1.8 Channel master offset ... and using a cone scalar on it ... C band performance was o.k. (although i consider 1.8 a minimum size for most C band transmissions here in the u/k )
The problems are with k/u ... the combination l.n.b,s are i think designed with prime focus dishes in mind .. the scalar rings are " flat" on the k/u part of the l.n.b so is not ideal for an offset dish ...

Another reason for reduced k/u performance is the dielectric plate in the C band part of the l.n.b ... a lot of the C band satellites covering u/k and Europe have circular transponders - so need the plate ... this kills the K/u signals for all but the strongest ones ... for me the combined unit did not give any better k/u result on my 1.8 with a dielectric plate fitted than i would have got from a normal l.n.b on a a regular 1.0 meter dish

But i dont doubt that the combo l.n.b,s work well on k/u - on large prime focus dishes - when receiving linear c band.