I thought some folks might get a kick out of seeing the major revisions of the TR-6 printed circuit board. The first three are almost the same in terms of overall design, but do demonstrate some of the evolutionary stages of early printed circuit board development and production. The fourth board, the late R-6D2-A revision, stands in contrast as a totally different design; you could even say it's a different radio altogether. Sure, yields were small and the pace of development was rapid during these early days of transistor radio production, so the parts used on these circuit boards changed regularly. While I did think it would be interesting to let the board revisions relate their own tale as part of transistor radio history, I am not quite crazed enough to try and show all the little differences one finds inside these radios.