In the 630 MHz range you can hear wireless microphones used by TV reporters, or at Disneyland many of the actors for live shows have these wireless mics on them. Interesting listening if you're close and the show is over, the mic is usually left on.
600 MHz is a little high for HF isn't it? :lol:
(In case you're wondering, HF is generally accepted as those frequencies between 3 and 30 MHz. 600 MHz is solidly within the UHF spectrum.)
It's good for any broadcast TV stations you might have between channels 35 and 52, and for some wireless mikes too. There's not a whole lot else that you can pick up around there, though, unless you have the special circumstances that others have mentioned. (like being at Disneyland)