A little radio history was made in Mexico, Missouri

I was at Forest Park Community College in St. Louis in 1975, while a bit of radio history took place in Mexico, Missouri.  The first solid state AM transmitter manufactured by the Harris Corporation was put in service at KXEO.  Hilmer Swanson headed up the design and manufacture of the Harris MW-1 in Quincy.  From a Harris Corporation newsletter:
Harris Corp March 1975 Newsletter MW-1

That MW-1 was still in use when I started at KXEO in 1978.  In 1980 the station purchased a larger FM transmitter from McMartin, and at the same time purchased a new BA-1K AM transmitter.  I was told the Harris MW-1 was "traded in" to McMartin,  as McMartin was very interested in the solid state technology.  While the BA-1K had a solid state exciter (the first modulated power stage of a transmitter), the BA-1K relied on 4 tubes to achieve its 1000 watts.

You may be wondering why the station would have gone from the newer all solid state technology of the Harris MW-1 back to tubes with the McMartin BA-1K. The KXEO tower at that time had massive amounts of static electricity jumping around the tower and guy wires with each passing thunderstorm, and that was enough of a jolt to the MW-1 to take out the final power stage on a fairly regular basis.