here has a list of sixty-two, 16-inch, 30-minute AFRS 33 rpm transcriptions from a WWII jazz radio program called "Downbeat." It ran from at least 1943 to 1948. Despite the fact that a jazz program and a jazz magazine of the same name operated concurrently and even featured many of the same artists they seem to have had no connection. I find this inexpiable.
Downbeat the jazz music magazine began publication in 1934 in Chicago. But Downbeat was no jingoist rag. Starting around October 1942, Down Beat began running a regular column titled Killed in Action. This was to honor the scores of musicians who died in action. But it also had a certain racial component. Civil rights was an increasingly prominent problem and drafting jazz musicians to fight a war when they lacked many of the basic rights of citizenship posed a very public dilemma. Nonetheless they were not anti-war in any other regard.
The selection of artists on the Down Beat radio program mostly ranged from vanilla to wholesome: Glen Miller, Harry James, Gene Krupa, Woody Herman, and Xavier Cugat but there are also some more daring picks. Fats Waller, Charlie Barnet, Spike Jones and Duke Ellington appeared on several shows.
The Downbeat program was cancelled in 1948. According to a note in Billboard it was replaced by DJ Gene Norman's jazz concerts. Gene Norman has been an announcer on some Down Beat programs as early as 1945, but so had Elliott Lewis. How Norman floated to the top I can't guess.
It is also notable that in the late 1940s-1950s there was a record label named "Down Beat." More here. They put out sides by Lowell Fulson, Ray Charles, Pete Johnson and others. But very little information is available otherwise. Currently I have assumed it is not connected to either the show or the magazine. In the 1960s the CRC (Caribbean Recording Company) also put out some discs under the name "Down Beat" that also of no relation to any of the above.