Thanks Balki and Cyril,
Balki, I appreciated that link and understand some of the frustration. I did try to use a wireless sender once before with little limited success. I had exactly your experience - worked well one night; failed in the morning. I was rather hoping that digital would be better than analogue but reading your thread has put a little damper on that; though I do think I will give it a try anyway.
Cyril, Some explanation: the difficulty in running coax is that we live in a town house here. I had to practically pull Optus in by the collar to run cable from the street to the basement ceiling which is under my study. The main need was for broadband internet and, as Optus was my corporate supplier, they felt they had to come to the party. I had the cable spliced to provide both internet and cable TV. Upstairs, unfortunately has no easy connection and we have beaut natural floor boards that cannot hide a cable. I was able to connect the output of the STB in the study back down under the floor to the common TV antenna cable in the MDF room that serves all units. From there to an old plug which the TV uses - I put in two amps along the way to keep signal quality up. I am contacting my cable guy to get him round to see if we can do something magic with a cable run.
Regards.