Re: Pre driver and driver transistors
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Again, you-all might do a little research by reading all of the posts from about a year and a half ago. No sense reinventing the wheel. There were several people working this issue… redesigning output transformers, changing the feedback components on the finals (oh yes, those parts are frequency dependent), adding another drive state, changing bypassing). As I recall, the group consisted of a DL, a VK, a K9, and another euro station… some of these people have since left the group. You might reread all of that dialogue and weigh that in with Allison’s ever-present posts.
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Gérard
I have not yet asked myself the question to replace some 3904. For me the 2n2222 is an "old Go anywhere " transistor.It's work fine, but it is at least over 50 years old, I was already changing some in the years 70/80. We really should study the case.
But the change does not stop there. It may be necessary to adjust resistances emitters, base. See if anyone has already put transistors other than 2n2222. Take the µbitx version6 schematic and find an equivalent to the BFR93w.
Look here: https://groups.io/g/BITX20/wiki/7641