The Central Coast Transmitters just retransmit the Sydney signals and the Newcastle Signals, all you need to do is have the antenna system designed to only pick-up 1 Central Coast Transmitter, whether it's Bouddi, Wyong or Gosford depends on what signal levels are available at your location from each.
The Antenna should be located so that the other 2 transmitter sites have weak signals at your place so that they don't interfere with the signals coming from the transmitter you've chosen.
You should get an Antenna technician in who has a Digital Field Strength Meter for measuring the signals, as this is the only way to work out what site to use and what location your antenna should go.
I had A friend over with the digital field strength meter (normally plays with dishes),do not have the figures of each transmission, but from what he has been able to establish the strongest digital signal is coming in via Gore Hill area Sydney and Newcastle channel 350-352 and this is being fed to the STB by the old VHF antennae? The normal VHF transmission looks like rubbish but the digital signal has the highest readings for strength and quality.
He did not think that position, mounting or cabling were a problem but suggested that changing over to the Quad coax and updating the masthead amplifier could help for a unit such as suggested by Alanh. MHU44 in a shielded box. To reduce noise would be a good idea.
The next strongest is Bouddi on the UHF antennae (even though the polarity of the antenna was wrong), followed by Gosford and Wyong, then Newcasle UHF transmitters? He claimed that all of the signals were good enough for a watchable stable picture and that there could be another reason why I get the problems in the bad weather.
He said that there could be the possibility that someone else in the area has a masthead amplifier or cabling that is faulty and the amplifier may get wet and start transmitting interfering with the normally good reception that I get?
So I guess my options are as follows.
1:Get a suitable antennae to point to Sydney to use the transmission from Gore Hill area, and or try removing the UHF antennae first.
2: Remove the VHF antenna and try maximising the transmissions from Gosford, Wyong and Newcastle.
3:Forget about both of the above and be happy with the transmission and channels available from Bouddi.
Will the transmitters in Gore Hill be still in operation once the current VHF system is closed down?
Many thanks for all of your help and comments