WITH the arrival of the hot summer, Commercial Radio II is organising a variety of interesting activities for young music fans. Under the ''Commercial Radio II Summer Sun Summer Fun'' programme, 17 activities are being lined up to whet the appetite. Among the many interesting functions are the ''Outstanding Pupils Award 1993'', ''My Favourite Song 2nd Quarter Voting'', ''Jacky Cheung Birthday Party'', ''Takeshi Kaneshiro Mini-Concert'', ''Super Fans Sports Day'', ''Dating Andy'', ''New Male Artists Mini-Concert'', ''Beach Show'' and ''International Leon's Fans Gathering''. Music fans should have a whale of a time as they will get to see their idols close-up. About 30 pop singers showed their support for the events at a press conference early this week. Among the stars who will be taking part are Jacky Cheung, Andy Lau, Leon Lai, Aaron Kwok, Sally Yeh, Sandy Lam, Faye Wong, Dicky Cheung, Andy Hui, Shirley Kwan, Alex To, Veronica Yip, Vivian Chow and the Grasshopper. Commercial Radio II Assistant Programme Director Wallace Kwok said that as a music station, it was only natural that they organised related activities for listeners. ''Starting last year, we have beefed up production for our summer programmes,'' he said. ''Apart from giving singers more opportunity to perform before their fans, we also hope the youngsters can relax themselves after their year-long schooling.'' All the activities in ''Summer Sun Summer Fun'' are open to the public. For free tickets, listen to Commercial Radio II for more details.