Is it possible to get both C-band and KU on same offset Dish?

angusc

Hi,

I'm a novice to multiple satellite reception but like to "play" with things and would like to know if it is possible to recieve both C-band and KU Universal band on the same 0.90m dish fitted with Motek H-H mount. I tried by attaching a C-band prime focus LNB but although i used a sat meter to pick the highest C-band signal I could not get any results on the blind scans that i tried. I have attached a picture of my "play time". Please could you advise me how i might be able to get this to work, I have looked thruogh the site sponsor pages for combined C-band and KU band LNB's but they do not seem to exist.

I'm living in Beijing and the satellites of interest are: 146E (KU), 138E (KU), 122.2E (RHC), 105.5E (C), 100.5E (C), 95E (KU). There are others but until i can get the above working.........

Thanx for all your advises
angusc

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pedro2000uk

What size is that dish and is that a diseqc motor?

We got C Band down to less than a 1m dish as a test in central UK, but it really limits how many satellites you can get on C band- better a 1.5m or more for C.

Putting an LNB at the side of the focal point on a moving dish has its problems because it is only really right at one place on the arc where you set it up.. once you move the dish it's always going to be variously off the focal point when you've lined the 2nd off focal point lnb up. You might use the C as the main focal point and the KU as the 2nd as the KU sats should be stronger.

It should be better using a combined Ku & C LNB but they are limited in range and you may find far better individual Ku & C band lnbs than the combined one.. gain/ noise wise.

If you are engineering adept you could make a manual or motorised swapper that moves the C or KU LNB into the focus point when chosen, then you could use the best KU & best C LNBs.

angusc

My dish is a Jonsa 90cm offset dish and the H-H Diseqc motor is a MOTEK 1200a unit. What combined LNB's are available and are the noise db any good? All i can buy here in China are imported LNB's that have 0.6 and 0.7 db sensitivity that are not the best to say the least and also cost 4 or 5 times more than what i can see them on the www.

I did not think to put the C-band LNB in the focal point of the dish, this may be something for me to try out. I'm not worried about the side LNB being off the focal prime spot of hte dish as I can correct this by changing the satellite Degrees setting for each of the C-band satellites using the H-H Diseqc motor mount.

Does anyone have any really good LNB brand and model recommendations for me to try to locate and purchase?

pedro2000uk

The offset lnb will only actually be in the right place at one point on the arc as a proper working offset LNB... after you have moved to another satellite for the main lnb and then moved the motor to get the offset LNB as near as possible in the focal point it will be off the focal point....higher or lower than the focal point depending on the direction you have gone from where you set it up and which side is it is...

If you put it above or below the main lnb at your top dead centre sat and have incline actuator control then that would do it, you would just have one position for each sat and say about 5 degree up / down to bring each LNB in/ out of the focus point of the dish- the offset LNB would still lose a bit but not much- 5-10%.

Just side by side you may get it to work for the C with KU on offset to a degree but it's going to lose some on the KU.

The other problem is that dish size .. 90 for C really looks on the low size for those sats there. +42dbW in Beijing are probably get-able.. +45dBW will be easy-ish and give a bit of rain margin. The 40dBW C stuff (most?) will struggle on a 90.

see the Best .1 thread for KU LNB updates