offset lnbf on prime focus 6' dish

[truckracer]

I am looking at a couple of 6' prime focus solid aluminum c-band dish antennas. One of the companies selling the antenna offers a KU band offset lnbf and bracket for use with these dish antennas so you can have both c and ku band on the dish.

I did not know that an offset lnbf would work on a prime focus dish.
Is this possible? or would performance suffer? I have never heard of anyone doing this. I had a friend of mine try to use a prime focus lnb on an offset dish and that did not work. Someone let me know. Thanks - Trucker

 

[sksatellite]

Its not going to work. Its all about f/D.
It is very important to choose a proper feed for each f/D ratio. Deeper antenna (prime focus) f/D from 0.32 to 0.25 while the offset antenna has the f/D ranging from o.50 to 0.60. You can do either one but not both, unless there special design.

You will never see a ku lnbf point at the center of the dish, It always a bit below the center line.

 

[boba]

A 6' dish is too small for "C"band the satellites are spaced too close together and a 6' has too wide a beam width to see only 1 satellite. If adjacent satellites have the same transponders active even if opposite polarization some signal will bleed through. 7.5' is the minimum for "C"band analog reception.

 

[tdti1]

A 6' dish is too small for "C"band the satellites are spaced too close together and a 6' has too wide a beam width to see only 1 satellite. If adjacent satellites have the same transponders active even if opposite polarization some signal will bleed through. 7.5' is the minimum for "C"band analog reception.

Actually it is 8.5 for 2 deg. but this is a good point, I would not get a dish under 10' myself. It should work great for ku though.

 

[kelljc]

A 6' dish is too small for "C"band the satellites are spaced too close together and a 6' has too wide a beam width to see only 1 satellite. If adjacent satellites have the same transponders active even if opposite polarization some signal will bleed through. 7.5' is the minimum for "C"band analog reception.

That is not correct: a 120 cm dish will get any c-band bird in the sky?. i've been putting in 120cm dishes for 23 yrs and as of this date no problem./ come back.

 

[tdti1]

Have you done this on the over crowded part of the arc? I do not want to argue but the laws of physics and proper mathematical calculations will prove you wrong.

I can get C-band on a 4-5' dish for fun, would I recommend it to someone, no.

 

[lee4519]

i took a directv lnbf and taped it to my 10 ft big dish close to the feed horn and tweak it and it works fine. i just have to move my dish up and down to get the other dtv satellites.

 

[lilyarbie]

Just wondering......

What kind of quality are you getting on the C-band dish? Also, can you describe how you've got it pointed on the dish and what the signal strength you are getting is?

 

[lee4519]

i get great quality it dont fade out in bad weather. it takes a little practice setting the lnbf right . use a signal meter it will help you . if you are not going to use the cband lb take a saw and cut the back of feed horn off at the polarrotor. you can then mount a lnbf inside. you have to play around with the best fit. dtv and dish are ku band signals and a big dish wil pick those signals up. some older mesh dishes had bigger holes in the screen but will work. you can then use your big dish controlls to move dish up and down to the correct satellite.