Chameleon, a jazz trio, plays a free concert this Sunday from noon to 2 at the Pavilion of the Old Post Office, 1100 Pennsylvania Avenue NW; call 289-4224 . . . The Houston Ballet continues at the Kennedy Center with Tchaikovsky's "Swan Lake" this Friday at 8; Saturday at 2 and 8; Sunday at 1:30. Tickets are $14 to $30 and are available at the Kennedy Center Box Office or by calling 857-0900 . . . The 1986 Recreational Vehicle Show is this weekend at the Stadium Armory Complex, 2001 East Capitol Street. The show runs Friday from 6 to 10; Saturday 10 to 10; Sunday noon to 6. Tickets are $5; children under 12, free. Call 547-9215. IN MARYLAND
The 16th Annual Annapolis Heritage Antiques Show is at the Parole National Guard Armory this Friday and Saturday from 11 to 9; 11 to 5 Sunday. Tickets are $4.50 at the door. The armory is at Hudson and West streets, Annapolis. Call 956-4900 or 535- 5118. IN VIRGINIA
Classical mime Mark Jaster appears this Saturday at 1 and 4 at the McLean Community Center's Alden Theater, 1236 Ingleside Avenue, McLean. Tickets are $4; call 790-9248 . . . The play "Annie" runs through this weekend at George Mason University's Patriot Center, 4400 University Drive, Fairfax. Shows are Friday at 8; Saturday at 2 and 8; Sunday at 2. Tickets range from $10 to $18 and are available by calling 432-0200.