Between 25 and 30 years ago, the IECEC proceedings carried a series of papers of the present authors and of other members of a JPL team on the problems and the desirable design features associated with the MHW RTGs to be used to power JPL’s Voyager I and II spacecraft. The Voyager I and II spacecraft have now successfully completed their original 12 year missions about 10 years ago, and are at distances of over 55 AU and 70 AU from the sun. The power systems worked almost precisely as predicted. The Voyager spacecraft seem to have several decades of life left to make more measurements outside of the solar system. The present paper gives a technical overview of the design process and problems.