EMRFD Message Archive 1688

Message Date From Subject
1688 2008-05-31 06:48:09 bkopski EMRFD FEEDBACK AMPLIFIERS – SIMPLIFIED
Hi All -

Yesterday's posting of similar title contained a lot of data – too
much maybe - in that I evaluated a very wide range of transistor
types, lots, manufacturers, etc in the same EMRFD circuit. As I
looked more closely at the rather widespread data array, I began to
see what I thought were a few patterns. Today I set about to slim
down that extensive data into what should be more easily viewed – and
be more useful - for most folks. Today's offering is contained in
just two .jpg's. It contains an obvious surprise and possibly a
point of confusion. (Note that yesterday's posting text can serve as
procedural reference for today's followup.)

The accompanying photo XtorGrp8 contains five traces. For this
picture I chose 4 transistor types that I thought would be of most
interest to HB'ers. The caption lists a reference, PN2222, 2N3904,
2N5109, and PN5179. It is clear that the amplifier performance is
highly influenced by the transistor selection – except for the
curious overlay of the 2N3904 and 2N5109 traces.

The surprise just noted prompted the photo XtorGrp9. Here we have a
reference trace, 2N3904, 2N5109, and a 2N3866. Amazing, huh? This
can easily prompt the ponderance: "just how many really different
transistor die/processes are there?"

Do keep in mind this is performance in a single circuit configuration
over a limited frequency range.

As always, comments are welcome – and I'd expect some from this!!