Those of us that are used to working with modern scopes don't often run into units
such as the 90921. Millen manufactured, and still does, oscilloscopes in many different
forms. Including those which were essentially just basic monitor scopes comprising
power supply, cathode ray tubes and simple circuitry to adjust brilliancy and centering
along with connections for the vertical and horizontal plates. This unit would provide
the needed vertical and horizontal amplifiers and a saw-tooth generator to provide
horizontal sweep. In many ways it is similar to the plug-ins used in more modern
The photo above is courtesy of Manuel Maseda W4SSB. This unit is owned by Rick Galardi, W1DEJ.