Named radio "Czar." Washington, D.C., March 31. Mark Foster Ethridge, now General Manager of the Louisville Courier Journal and Times, today became radio's first "Czar". He has agreed to serve without salary as President of the National Association of Broadcasters until the position is filled permanently. 41 years old, Ethridge is a native of Mississippi and has been a newspaperman for the last 25 years, 3/31/38