TWIDDLE the dial of a short-wave radio and you never know what you will get. Through the hiss of static you may hear Cuban propaganda, football from Brazil or Chinese opera. Unlike other radio broadcasts, short-wave transmissions, bouncing off the ionosphere, can connect any two points on earth. One hazard is physics: signals wane and wax during the day. Another is governments. In the cold war communist regimes jammed Western stations. Now the threat is budget cuts.