There is also an aviation aspect to this story. This is what I remember being told.
In the late 50's and early 60's the Federal Aviation Agency was responsible for the installation and maintenance of all the civilian ground systems. Including, control towers, NDBs, VORs, LF ranges and TEWBs. TEWBs used the old 1/4 inch magnetic tape. At 7 1/2 inches per second a 30 second recording required over 18 feet of tape on a loop that was stretched back and forth between pulleys mounted on a wall. Knowing that there had to be a better system, someone that knew Bill, knew he was pretty sharp figuring out this sort of problem. The result was a 3" x 3" x 3/4" aluminum box with a roll of tape that was pulled from the center run past the recorder/playback heads and rewound on the outside of the roll. You could get over a minute of recording on a little 3 x 3 box, amazing.