However I was also given an earlier model Dunn Gyromatic (made before the merger of Parris & Dunn) in exchange for restoring a farm radio, that I restored to displayable condition (but not functional, due to some missing & hard to find parts) that I have displayed along with some of the 6 volt farm radios in my antique radio collection. There were several small companies making similar units in the 30's before F.D.R's rural electrification program brought power to the countryside. Interestingly, this company continued production up into the 1950's shipping many systems to Canada and south America where most of the surviving examples exist today; just another little bit of Iowa history triva. 

This sorry looking thing is what is left of a 6 volt 200 watt Parris-Dunn farm radio wind charger circa 1935 that was given to me after spending decades under a collapsed farm shed. . I made a trek to Clarinda, Iowa where these were made and was able to gather some history that is now posted on a Parris-Dunn history web site. But ultimately gave up on trying to restore it to displayable condition.  The tail wind vain is now decorating the wall of my inverter-battery room.