A DN receiver will not work to my knowledge.
Sadoun probably has the best prices for the level of receiver he is selling out there. I have bought from him and other dealers. The plate is for receiving circular beams. Most are linear but there are a few sats over the Atlantic that are circular. 40.5 is one of them which is why I use a BSC lnbf on one of my dishes. I will look into the EBay thing. So if you are not planning on trying to receive anything circular the plate is of no use to you. Without the plate it does linear which is what your 4DTV wants along with most FTA.
DN is circular but is scrambled so of no value there. Just for the record if you check my signature you will see I have a 4DTV receiver and a BSC lnbf but they are not connected to each other. You may possible be able to do it by reverse slaving through a DVB MPEG2 receiver first.
EDIT:
I went to Ebay and you are correct. I think the bulk of the problem is lack of knowledge (sorry but I do think that) and we have all been there. I do not know how to setup the receiver to utilize the lnbf. My BSC is the -2 version which uses a
DiSEqC switch. You will still need to run separate lines to the receiver from each port on the lnbf. Do you have it connected that way? You will not be able to use the jumper that came with the lnbf to combine the feeds into a single line.
I will be home later and check through settings in my receiver. Perhaps I can find where to change yours and let you know tomorrow. Have you checked the mesh in the dish yet?