I have tried it with nothing but the 30m PC cable plugged into the Aerial cable and this didnt work.
Then i tried the aerial cable plugged into the amp and just the 30m pc cable coming out of it (This worked the best, almost perfect) But this poses the problem of how to connect all the other tv's and how to get the sky signal to the PC aswell. When the aerial goes the sky box then to the amplifier with just the 30m PC cable is is stuttery again.
It is currently on UHF channel 38 according to the sky box, I have never really fiddled with this as when the computer is in the lounge it accepts the mixed sky and uhf feed fine with no problems, just when the cable gets longer the problems come. I guess i could try another rf channel any suggestions which would interfere the least?
i can appreciate that, it is very useful though so thanks for the effort. I think the easiest thing for me to do, after trying different uhf channels, would be to just split the UHF cable on the roof near the aerial and take it the short route to my room where no interference is, then i can be pretty sure its got the least possible number of possible problems. I can use the existing cable i have just for the sky feed and analogue channels if neccessary.