bodge
Regular Member
I picked up this second hand 2.4 m dish and want to be able to use it to pick up the BBC abroad. What changes need to be made to the LNB / feedhorn to make this possible ?
bodge said:want to be able to use it to pick up the BBC abroad
Channel Hopper said:A complete change of front end (its a C band voltage switching device and feed)
Measuring up a feed for good performance at Ku band will require some details on the excat diameter and depth of the reflector. - depth over diameter will give a figure somewhere between 0.3 and 0.4
Once you have this figure the most appropriate feed design in C120 configuration will match for the best efficiency.
Analoguesat said:Bodge - where are you located? We cant tell you if you will get the BBC without this information - "abroad" covers a lot of ground!
Channel Hopper said:Then it should work as it has about twice the area, if the efficiency remains the same
Rain fade is usuallty 2db or about 40% of the loss
Channel Hopper said:Get out a tape measure
Channel Hopper said:You need the depth of the dish , from rim down to the surface of the reflector at its deepest point to work out the exact f/d ratio and the proper focal point. Unless you get this figure, you will not get a performing dish.
Other factors come in to it as well, how well the dish is made and how true the reflector surface is all round, moreso by a factor of three for Ku band, not much you can do if its off.
You should not be thinking of using anything you already have for the new front end.
bodge said:Thanks Channel Hopper. One more question; does it matter which C120 flange feedhorn I use ? Does the size of the dish make any difference ?
Channel Hopper said:I must be in a bagel wormhole toke