Cathcart was born in Michigan City, Indiana, United States.
[3] He was a trumpeter for the U.S. Army Air Force Band and a member of big bands led by Bob Crosby, Ben Pollack, and Ray Noble.
His friend Jack Webb was playing the part of trumpeter Pete Kelly in the movie Pete Kelly's Blues and told Cathcart he should supply the music.
[3] The band from the movie stayed together in the 1950s for performances and recordings under the name Pete Kelly's Big Seven.
[4] Cathcart also supplied music for the TV show Dragnet, which starred Jack Webb as Joe Friday.