Most days, the best jazz station in the world plays jazz only 40 percent of the time. But 14 times a year, WKCR at Columbia University fêtes select jazz greats with 24-hour birthday blowouts. Now working from home, the station’s stalwart, all-volunteer staff showers late April with three of the most refreshing: on the 22nd, Charles Mingus’ soulful strife; on the 25th, Ella Fitzgerald’s vintage champagne; on the 29th, the peaceable jungle of Duke Ellington. —E.E.