May have been different in Australia? RF modulators in the US pretty much universally offer an option for channels 2 or 3, or else 3 or 4, because of the way the markets were divided up and frequencies assigned, no matter where you lived one of those would not have a nearby station broadcasting on. I actually lived about midway between two markets (Philadelphia and New York City) so depending on which way I pointed the antenna, I could get 3 from philly or 2 and 4 from NYC. Which I did quite often - only the NYC PBS station showed Dr. Who and Monty Python. Never interfered with my early game consoles, an early one similar to Odyssey which had the tennis and hockey variants, and later the classic Atari 2600.
I do think the issue is more of one of compatibility with modern TV sets - do you have an older set around try this with, one that still has an analog tuner? People often give away old CRT TVs because they are effectively worthless but the relatively sloppy analog synthesis and possibly higher raw sensitivity of an old analog set may be what you need to get a clean image from this old game system. Shame, it was just a few weeks ago I sent the last such animal I had to the recycler. It was only a 5" B&W and the TV display was slightly fuzzy due to a mod I made back in the days when I knew some signals needed to be shielded but not exactly how to go about doing it in a foolproof manner - my first computer had an RF modulator that I couldn't get to work no matter what, so I opened this TV up and discovered the video and tuner sections were on two separate boards connected via a piece of coax, complete with RCA connectors on each end. Plugged the computer into the RF input side and the display worked great, so I got some coax and a SPDT toggle and cobbled on an RCA jack where the switch could select the source to be the tuner board or the jack I screwed to the back of the case. Worked great but probably broadcast a bunch of noise and it was somewhat susceptible to external noise. Completely analog set, would have been perfect for testing an old game console like this.