CREATE TABLE table_75078 ("Callsign" TEXT, "Area served" TEXT, "Frequency" TEXT, "Band" TEXT, "Fate" TEXT, "Freq currently" TEXT, "Purpose" TEXT)

Which area served has a Callsign of 5ddn?
SELECT "Area served" FROM table_75078 WHERE "Callsign" = '5ddn'
SELECT "Area served" FROM "table_75078" WHERE "Callsign" = '5ddn'