[462ron]

Hi all, I’m curious as to why there is a difference between some sets as to how they obtain negative bias voltages, in this case both Philco sets. I picked 2 random sets to illustrate my question. In this first set, you can see the center tap of the power transformer develops a negative voltage going through the bias resistors 60 and 59 to chassis ground with no bypas or filter electrolytic.

        In the second set, center tap goes through bias resistors 33 and 34 to chassis ground but there is also a filtering or bypass capacitor of 10ufd #31. This filtering is absent in the first set! I’ve always wondered why there is that cap in one set and not the other considering the similarities of both circuits!

Ron