On 7/1/2018 9:50 AM, Martin Kratoska wrote:
The 2N3553 is a brutal 7 watt device in a TO-39 metal package. Chris
Trask, N7ZMY mentioned some unparalleled IM characterics
I used one of these 40 years ago to build a 95 MHz power oscillator
to excite a rubidium plasma lamp in an HP rubidium frequency
standard. It was indeed bulletproof, although I was only
generating about 2 watts IIRC. I'm sure the data sheet
says nothing about IMD or even beta vs collector current
because these are of no importance for the intended application.
BTW, the 2N3553 was already at least 10 years old even in 1979.
If you want to get into the re-purposing game, you have to
characterize each individual transistor for the characteristics
that count. A curve tracer is easy to come by, and you can
also build a socketed amplifier to do IMD testing on. I
wonder if N7ZMY has a good design for a homebrew two tone
generator, which is the main obstacle for IMD testing.
This is especially the case for something as ubiquitous
and disparate as the 2N2222. You never know what you are
going to get beyond what the JEDEC number specifies.
Experts at NIST due this kind of thing regarding phase
noise, and the 2N2222 was one of their favorites. But
they tested every one themselves.
Rick N6RK
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