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!! Cordially, Bob K3NHI

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!!

Cordially,
Bob K3NHI