On 10/28/2015 10:38 AM, Hal Murray wrote:
[email protected] said:
The 2N5179 in the 10811 is selected for minimum beta and Ft at 20 mA, which
is the start up condition due to the ALC being at full gain. It has a
special HP part number, so you wouldn't know this just looking at the parts
list.
How much of a difference does that selection step make?
I'd expect the parts within a batch to be very similar, more so for mature
parts.
All I can tell you is that Burgoon found a non-zero number of
2N5179's that wouldn't start. Knowing the way things were done,
he probably got a response from the vendor to the effect that
it was simply an unspecified parameter and they only guarantee
JEDEC specs and the transistor(s) he found were not a fluke.
HP greatly discouraged the batch qualification paradigm, although
the did resort to it when justified. It was not justified for
the 10811.
Rick
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