Guessing you mean Rumbalara Reserve?
For FM radio I reckon I can get better coverage of the populated areas of the CC from Mt Elliot over Somesby, remember I wanted to move CoastFM to there (not happening now though), & the original 2CCC (CoastFM) transmitter was at Mt Elliot probably for that reason?
I believe the commercial stations put their transmitters at Somesby to get good coverage along the F3/M1 freeway, probably parts of the freeway South of the Mooney Mooney Bridge wouldn’t get very good reception from Mt Elliot?
As far as UHF TV goes, no there’d be too many areas of the CBD & South of the Rumbalara reserve hill (East Gosford) & even parts North Gosford, that’d be shadowed too much for good or any reception from Mt Elliot, I know Rumbalara reserve site serves right down the Brisbane Water areas, Woy Woy, etc might also be shadowed too much from Mt Elliot, I know there’s people down around Umina & Ettalong get their TV from Gosford, even though Bouddi is much closer.
The coverage maps on the TXA web site are pretty accurate. https://www.txaustralia.com.au/tvcoverage