How to add a C/KU LNBF to an offset dish.

[aar5ac]

Hi;

I don't see any combo c/ku lnbf's on the site. The ones I have seen are big ungainly monsters meant for the bigger dish's. On my 100cm dish I would be exceedingly lucky to get a usable C-band signal but I thought I would have better luck for audio only. A little later on I might upgrade from my 100cm dish to 120cm dish and from what I can figure with the eirp's I could get a watchable C-band signal from some of the higher power satellites. Would you get a small, seperate C-band lnb and rig it below the KU feed and then use a disqec switch?? Just looking for someone who has played around with this a bit.

T

[bobkat]

You won't see any C-Band LNBs to fit 100 or 120 cm dishes because C-Band signals need a minimum dish diameter of about 5 feet to work; this is because their frequencies are lower than KU and hence the wavelengths are longer so a larger reflector (dish) is needed.

kat

[aar5ac]

Yep, I fully realize that. But I have read postings from people before who use a large KU dish for C-Band analog audio and it works just fine for them. I've also seen people who have used a 4' dish (120cm) for C-band analog tv signals and it works on the stronger birds who have an eirp of over 42 or 50 I believe. So I know it can be done just looking for how. But I'm thinking the 4' dish might possibly be a prime focus dish so as I said I'm not exactly sure how it was done.

[dtsexpert]

Analog is different than digital. With analog, you will see distored picture even with weak signal. For digital, if you don't pull enough singal to get lock, you won't see anything.
120cm will not get you any digital C-band. Here is the reason:
1. C-band lnb or lnbf for off-set dish is very rare and expesive. As I remember, there is a company in Australia makes it.
It's commercial line, meaning it might cost you more than 1K just for the lnb or lnbf.
2. If you use a comsumer line C-band lnb or lnbf which designed for prime focuse dish with your off-set one, it will not work well since the focus distance of these 2 type of dishes are different.
3. I use a 6ft solid prime focus dish for C-band PAS9, I get most of the channels. But PAS9 is a uniqe bird (there are no C-band birds close to it, therefore no interference from adjendent ones)
Well, the bottom line is forget about using any off-set ku dish for C-band...:-(
Michael

Originally Posted by aar5ac

Yep, I fully realize that. But I have read postings from people before who use a large KU dish for C-Band analog audio and it works just fine for them. I've also seen people who have used a 4' dish (120cm) for C-band analog tv signals and it works on the stronger birds who have an eirp of over 42 or 50 I believe. So I know it can be done just looking for how. But I'm thinking the 4' dish might possibly be a prime focus dish so as I said I'm not exactly sure how it was done.