Following World War I, radio experimentation at St. Olaf began with physics experiments in 1918, when five students and a professor built a small transmitter, using a wire antenna strung between the campus chapel and the college's "Old Main" (the tallest nearby building).
[1] In 1921, the college was issued a "Technical and Training School" license with the call sign 9YAJ for the experimental operations,[2] which began to include audio broadcasts in addition to the original Morse code transmissions.
However, effective December 1, 1921, the Department of Commerce, the regulators of radio at this time, adopted a regulation that formally created a broadcasting station category, and stations were now required to hold a Limited Commercial license authorizing operation on wavelengths of 360 meters (833 kHz) for "entertainment" broadcasts or 485 meters (619 kHz) for "market and weather reports".
)[6] On November 11, 1928, a major reassignment of station transmitting frequencies took place, under the provisions of the Federal Radio Commission's General Order 40.
[13] The college continued to operate WCAL-FM 89.3 until selling it to Minnesota Public Radio in 2004, resulting in changing the call letters to KCMP.