CREATE TABLE table_35111 ("Callsign" TEXT, "Area served" TEXT, "Frequency" TEXT, "Band" TEXT, "Freq currently" TEXT, "Purpose" TEXT)

Which freq currently has 0 684?
SELECT "Freq currently" FROM table_35111 WHERE "Frequency" = '0 684'
SELECT "Freq currently" FROM "table_35111" WHERE "Frequency" = '0 684'