Ku and C Band on a single dish

[Chr0nik]

Hi,

I'm currently playing with the idea of having KU and C Band on a single dish so that when the dish moves to a position, I could get the KU and C side of sat - something like this. I'm using a CM 120cm to do so and with the setup as shown on the images.

I have the dish parked at 40e so I should get C but with setup below but it does not seem to work.


Can you please advice on what can be changed or give ideas?

Thanks!

 

[TJExcalibur]

I would think the C Band lnb is not focusing on the dish centre.

 

[John]

Hi,

I'm currently playing with the idea of having KU and C Band on a single dish so that when the dish moves to a position, I could get the KU and C side of sat . I'm using a CM 120cm to do so and with the setup as shown on the images.

I have the dish parked at 40e so I should get C but with setup below but it does not seem to work.

Can you please advice on what can be changed or give ideas?

Thanks!

It's asking a lot for a 1.2 dish to do what your set up is showing. If you do not have elevation control of the dish, which would give you the option to tweek the dish up / down for optimum signal then the next option would be to mount the Cband lnbf at the central focal point and put the Ku lnb to the side of it, not above and then tweek the dish left or right to optomise Ku signals. There is some bracketry fabrication involved to do all this and with very limited space available at the antennas focal point position it's a difficult job to achieve - possibly taking out small cuts of the Cband scalar to clear the lnb support arms. Is that a 1.8 in the back ground ?.

 

[Channel Hopper]

You should invert the dish to prevent water running into the LNB. As TJ says you would need to elevate the dish slightly to focus the signal onto the C band feed. Fitting a small motor where the elevation (or declination) threaded bolt /locknut goes, plus loosening the other nuts slightly might be the way to go.

 

[Chr0nik]

Is that a 1.8 in the back ground ?.

It is a 1.8m

Cannot mount it at the moment as it's too big for the garden and will need to redo the shed area in a couple of weeks

 

[Stevenvc19]

How about the coaxial cable going into the LNB?
It looks a bit dodgy...

 

[TJExcalibur]

Maybe swop the LNB's. The C band lnb needs to be perfect and you have a bit more leeway with the KU band lnb.

 

[nelson_b]

Hi
I,m sure you will need elevation control to get the best out of the arrangement you have chosen ...
I,v had a C-K/u arrangement on a 1.8 in the past that worked well overall ..... pic enclosed ... i never tried the same setup on a 1.2 as i think its too small for most c band sats ... even with the C band the l.n.b. in the center its going to be very limited on 1,2.

 

[Chr0nik]

@nelson_b that setup looks pretty nice!

I ended up using another dish for KU band - plan to get KU on a 110cm dish and C on the 120cm.

 

[Terryl]

The "C" band LNB looks to be too far off center for good reception on "C" band, and that dish is not the correct shape for an off-set LNB configuration, an elliptical dish* would work better.

*Elliptical dish, one that is wider left to right to cover off center signals.

And the dish in question would be very sketchy on receiving a "C" band signal, it's a bit too small, you may get lucky if the "C" band satellite is a strong one on "C" band.

A 2 meter dish is about as low as I would go, I use a 3.5 meter dish for "C" and "Ku" band operation with one dual band LNB at prime focus.

 

[Gladstones]

Something like this may help