Hy, grumpypsat, I am running both systems here off one external antenna, I bought a bnc tee splitter which is connected to the output of the jim preamp with pigtails running to RB & SBS. Tee splitter from maplins also bnc to sma connecter for RB from maplins, Waiting on delivery from USA on new external antenna which i hope will be a big improvement here, ( I live in a very narrow Valley) will post results when up & running.
Cheers Peteeds. 2W1 FJZ